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Jassa variegatus (Leach, 1814) Stebbing (1899a) compared Leach’s (1814) descriptions of the genera Podocerus and Jassa, collected from Devon, England, demonstrating that the two genera were valid, while previously, it had been thought that the two were the same. This study initiated the transfer of species to each genus, with Podocerus variegatus Leach, 1814 being the type for the genus Podocerus. Conlan (1990) examined the syntypes NHM 295b and 285d of Podocerus variegatus and found them to be indeed in the genus Podocerus. Jassa pulchella Leach, 1814 erected by Leach as the type for the genus Jassa (NHM 296a–g; lectotype: 296e), is now J. falcata (Montagu, 1808) (holotype: NHM 603a). Asecond species of Jassa described by Leach (1814), J. pelagica, was transferred by Stebbing (1899a) to Parajassa. Stebbing (1899a) documented the taxonomic confusion surrounding these three species over the 85 years between Leach’s publication and his own. Conlan (1990) mis-interpreted Stebbing (1899a) in thinking that there werestill specimens of Leach’s type series for P. variegatus that contained Jassa. However, this appears to be not the case, since P. variegatus and P. pelagica had their types validated by Conlan (1990) along with the type species for the genera Podocerus and Jassa. Therefore, the name J. variegatus is invalid (it is actually P. variegatus)., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on page 161, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Leach, W. E. (1814) Crustaceology. The Edinburgh Encyclopedia, 7, 402 - 404.","Stebbing, T. R. R. (1899 a) XXXVII. - On the true Podocerus and some new genera of amphipods. Annals and Magazine of Natural History, Series 7, 3 (15), 237 - 241. https: // doi. org / 10.1080 / 00222939908678113","Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288","Montagu, G. (1808) Description of several marine animals found on the south coast of Devonshire. Transactions of the Linnean Society of London, 9, 81 - 114. https: // doi. org / 10.1111 / j. 1096 - 3642.1818. tb 00327. x"]}

Jassaalonsoae Conlan, 1990 (Table 13, Figs 88–91) Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin without a fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with a row of short setae along its length; carpus with a cluster of moderately long setae at the anterodistal junction of the propodus (setal length about 1/3 the length of the anterior margin). Gnathopod 2: basis with a row of setae along the anterolateral margin (at least some setal lengths>40% of the basis width); carpus and propodus, setae on the anterior margin short and simple (setal length Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process underlying about 1/3 of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae (only the usual short setae at each dorsolateral cusp). Thumbed male: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmar defining spines not produced on a ledge, present in small thumbed males but absent in large thumbed males. In major males, the thumb is distally squared, the posterior margin sinuous. The dactyl is expanded close to the junction with the propodus but is not centrally toothed. Minor form males have a short, squared thumb and a dactyl tooth. Subadult males have a small prethumb. Adult female: Antenna 2: large animals without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmsinuous. Remarks. Jassa alonsoae, J. justi, J. fenwicki, J. ingens and J. hartmannae have a fringe of setae along the anterior margin of gnathopod 1 which may be robust and spine-like (Figs 88–90, 92, 95, 99 and 104). Jassa alonsoae differs from the others in having long setae on the basis of gnathopod 2 while the others have short setae similar to the basis of gnathopod 1. The row of setae on the gnathopod 1 basis is a distinctive character, which is only known for these Southern Hemisphere species. However, it is difficult to see on small animals and in J. ingens the setae do not run the full length in all animals (Fig. 99). The other Southern Hemisphere species (J. thurstoni, J. kjetilanna and J. gruneri) seem to lack this fringe although there can be minute setae present (Figs 93, 96 and 102). The sinuous shape of the female’s gnathopod 2 palm is a feature of several (but not all) Southern Hemisphere species also (J. alonsoae, J. thurstoni, J. fenwicki, J. kjetilanna, J. ingens and J. gruneri) (Figs 88, 90, 93, 95, 97, 100 and 102). However, it is not unique to the Southern Hemisphere as the other two Southern Hemisphere species, J. justi and J. hartmannae have shallowly concave palms (Figs 92 and 104) and the Northern Hemisphere J. myersi has a sinuous palm (Fig. 85). The other Northern Hemisphere species (and the transhemispheric species) have more clearly concave palms. Jassa alonsoae has been found more frequently than the other Southern Hemisphere species (Fig. 11). It has a wide longitudinal range but has not been found south of 60°S. Specimens described by Stephensen (1949) as “ Jassa pulchella ” w ere examined (SNM) and are J. alonsoae. Conlan (1990) noted other mis-identifications. Monod (1926) mentioned a collection of “ J. falcata ” from the carapace of the spider crab Eurypodius latreilli in the Strait of Magellan. Although these specimens have not been seen, they may be Jassa alonsoae as this species has been collected in this area and it was found on spider crabs in a Falkland Island collection (AM P.31689). Monod’s illustration of the female gnathopod 2 resembles that of J. alonsoae. Stebbing’s (1888) “ Podocerus falcatus ” from Greenland Harbour, Kerguelen Island (Challenger station 149E) may also be J. alonsoae. Its sinuous gnathopod 2 palm suggests an indigenous Southern Hemisphere species and J. alonsoae is the only species known from Kerguelen Island (Fig. 11). It is figured by Stebbing (1888) on Plate CXIX along with a female collected off the ship’s screw at Challenger station 142, off South Africa. Examination of this female (NHM) found that it is not J. alonsoae but J. marmorata. A description of the Challenger stations at http://www.19thcenturyscience.org/HMSC/HMSC-INDEX/index-linked.htm indicates that there was a second collection of Jassa at Kerguelen Island (Challenger station 149) but this was from the ship’s screw “after leaving the Cape ”. Examination of this collection found it to be also Jassa marmorata, indicating that this species was travelling with the ship., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 138-143, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288","Stephensen, K. (1949) The Amphipoda of Tristan da Cunha. Results of the Norwegian Scientific Expedition to Tristan da Cunha 1937 - 1938, 3 (19), 1 - 61.","Monod, T. (1926) Tanaidaces, Isopodes et Amphipodes. In: Commission de la \" Belgica \" (corp. auth.), Expedition Antarctique Belge: Resultats du Voyage de la Belgica en 1897 - 1899 Sous le Commandement de A. de Gerlache de Gomery (Zoology). J. - E. Buschmann, Anvers, pp. 1 - 67.","Stebbing, T. R. R. (1888) Report on the Amphipoda collected by HMS ' Challenger' during the years 1873 - 1876. Report on the Scientific Results of the Voyage of HMS ' Challenger' during the years 1873 - 1876, Zoology, 29, 1 - 1737."]}

Key to the world species of Jassa (both sexes) 6 1 Gnathopod 2, basis, at least the distal part of the anterolateral margin bearing a fringe of setae (at least some setal lengths 20–40% or more of the maximal basis width) (e.g., Figs 15, 28, 78, 88 and 102) (fringe alsopresent in juveniles but may be less pronouncedthanin adults...e.g., see Fig. 102)............................................................... 2 - Gnathopod 2, basis, setae short, minute or absent (setal lengths J. staudei Conlan, 1990 - Gnathopod 2, propodus, setae on the anteroproximal margin short or absent (setal length J. alonsoae Conlan, 1990 - Gnathopod 1, basis, anteriormarginwithoutarowof spine-likesetae (Figs 85 and 102)................................5 5 Gnathopod 1, carpus, anterodistal margin with a seta or cluster of setae at the anterodistal junction of the propodus (seta(e) ~40% thelengthof the carpus) (Fig. 85)......................................................... J. myersi Conlan, 19907 - Gnathopod 1, carpus, anterodistal margin without a seta or cluster of setae at the junction of the propodus (Fig. 102).............................................................................................. J. gruneri Conlan, 1990 6 Uropod 1, peduncular spinous process that extends ventrally from the peduncle and underlies the rami very short (±10% of the lengthof thelongest ramus) (Fig. 65)................................................... J. borowskyae Conlan, 1990 - Uropod 1, peduncular spinous process that extends ventrally from the peduncle and underlies the rami at least 25% to 50% the lengthofthelongestramus (e.g., Figs 42, 88 and 99)............................................................7 7 Gnathopod 1, carpus with a seta or cluster of setae at the anterodistal junction of the propodus (seta or setal cluster may be slightly lateralormedialandshortoraslongasthe carpus) (e.g., Figs 15, 22, 29, 31, 62 and 81)................................8 - Gnathopod 1, carpuswithoutasetaorclusterofsetaeattheanterodistaljunctionofthepropodus... J. monodon (Heller, 1866) 8 Gnathopod 1, carpus, seta or cluster of setae at the anterodistal junction of the propodus short (length J. valida (Dana, 1853) - Telson, tip without apical setae (though the usual upright setae at each lateral cusp are present). Antenna 2, large thumbed males and adult females, with dense plumose setae on the posterior margin of article 2 and the flagellum. Gnathopod 2, propodus of major form thumbed male, thumb wide, tip squared, spine or spine group on the posterior margin at the origin of the thumb absent (character statesdifferintheminor form) (Figs 15–16)..................................... J. marmorata Holmes, 1905 10 Gnathopod 2, basis and propodus, anterior marginal setae abundant and plumose (Figs 62–63). Mandibular palp, article 2, with a fringeof setaeonthedorsalmargin (Fig. 64)................................................. J. oclairi Conlan, 1990 - Gnathopod 2, basis and propodus, anterior marginal setae sparse and simple (Figs 22, 28 and 78). Mandibular palp, article 2, withoutafringeofsetaeonthedorsalmargin (Figs 27, 30 and 82)................................................11 11 Telson, tip bearing apical seta or setae in addition to the usual upright seta or setae at each lateral cusp (Fig. 28).................................................................................................. J. morinoi Conlan, 1990 - Telson, tipwithoutapical setae, onlywiththeusualuprightsetaorsetaeateachlateralcusp (Figs 22 and 78)..............12 12 Antenna 2, large thumbed male and large adult female, peduncular article 5 and flagellum, posterior margin bearing dense plumose setae (Figs 22 and 23). Gnathopod 2, propodus of major form male, thumb tip acute; spine or spine group on the posterior margin at the origin of the thumb absent (although present in small thumbed males) (Figs 22 and 23). Gnathopod 1, female propodus, palm straight to shallowly concave. Gnathopod 2, female propodus, maximum width about 50% of maximum length, palmar anglenotclosetothedefining spines; spinestightly clustered (Fig. 26)........................... J. slatteryi Conlan, 1990 - Antenna 2, thumbed male and large adult female, peduncular article 5 and flagellum setae not plumose (though may be microscopically pectinate) (Fig. 81). Gnathopod 2, propodus of major form male, thumb tip angled posteriorly, spine or spine group on the posterior margin at the origin of the thumb present (Fig. 78). Gnathopod 1, female propodus, palm convex. Gnathopod 2, female propodus, maximum width about 65% of maximum length, palmar angle close to the defining spines; spines sequential 6 This key is limited by incomplete knowledge of J. kimi, J. laurieae, J. monodon and J. shawi. Sufficient information for J. kimi, J. monodon and J. shawi allow for their inclusion but Jassa laurieae has been excluded because its characteristics are unknown posterior of pereon segment 4. See Table 11 and Remarks section for J. laurieae for distinguishing character states. 7 J. myersi appearstwiceinthekeybecausethesetalfringeontheanterolateralmarginofthebasisofgnathopod 2 canbe interpreted as being present or absent due to the sparseness of the setae on some individuals (Fig. 81)............................................................................. J. carltoni Conlan, 1990 13 Uropod 1, peduncular spinous process that extends ventrally from the peduncle and underlies the rami short (J. myersi Conlan, 1990 - Gnathopod 1, carpus, seta or setal cluster at the anterodistal junction of the propodus minute (J. shawi Conlan, 1990 15 Pereopods 5–7, anterior margin of the propodus, spines strong and spine row extending half or more of its full length, propodus expandedornotexpanded forgrasping (Figs 92, 95 and 99)......................................................16 - Pereopods 5–7, anterior margin of the propodus, spines mostly on the distal half, propodus not expanded for grasping (e.g., Figs 42, 48, 93 and 96)........................................................................................18 16 Gnathopod 1, carpus, seta or setal cluster at the anterodistal junction of the propodus about 1/3 the length of the carpus and slightly lateral and medial. Body length at maturity 15–25 mm (thumbed males and females with setose brood plates) (Fig. 99)............................................................................................ J. ingens (Pfeffer, 1888) - Gnathopod 1, carpus without a seta or setal cluster at the anterodistal junction of the propodus. Body length at maturity 5–9 mm (thumbedmalesandfemaleswithsetosebroodplates) (Figs 92 and 95)............................................17 17 Pereopods 5–7, anterior margin of the propodus expanded proximally for grasping. Antenna 2, thumbed male, posterior margin of article 5 andflagellumdenselyclothedinplumose setae. Gnathopod 2, female, palmof thepropodussinuous (Fig. 95)............................................................................................ J. fenwicki Conlan, 1990 - Pereopods 5–7, anterior margin of the propodus not expanded proximally for grasping. Antenna 2, thumbed male, posterior margin of article 5 and flagellum without plumose setae (though setae are minutely barbed). Gnathopod 2, female, palm of the propoduswithadistinctledgedistalof thepalmardefiningspines (Fig. 92).......................... J. justi Conlan, 1990 18 Gnathopod 1, carpus with a seta or setal cluster at the anterodistal junction of the propodus (length about 25% of the carpus length) (Fig. 93)............................................................................ J. thurstoni Conlan, 1990 - Gnathopod 1, carpus without a short seta or setal cluster at the anterodistal junction of the propodus (e.g., Figs 42–43), or if seta present, length J. falcata (Montagu, 1808) - Uropod 3, inner ramus without central spines (only the usual spine at the tip) (Fig. 48). Antenna 2, large adult male and female, posterior margin of peduncular article 5 and flagellum article 1 without plumose setae (Fig. 48) (although setae may be minutely barbed) (Fig. 50). Gnathopod 2, female propodus, palmarangle acute, close tothedefining spines (Figs 51 and 52)............................................................................................ J. herdmani (Walker, 1893) 21 Gnathopods 1 and 2, basis, anteriormarginbearingafringeof setaeorspines (Fig. 104)......... J. hartmannae Conlan, 1990 - Gnathopods 1 and 2, basis, anterior margin without an obvious fringe of setae or spines (setae minute or restricted distally (Figs 37, 60 and 96)..........................................................................................22 22 Gnathopod 2, female, palm sinuous (Fig. 97). Gnathopod 2, propodus of the major form thumbed male, thumb short with acute tip, spineorspinegroupontheposteriormarginattheoriginof thethumb onaledge (Fig. 96). Southern Hemisphere................................................................................... J. kjetilanna Vaderand Krapp, 2005 - Gnathopod 2, female, palm concave (Fig. 37). Gnathopod 2, propodus of the major form thumbed male, thumb long with rounded or incised tip, spine or spine group on the posterior margin at the origin of the thumb residual or absent (Figs 39 and 60). Northern Hemisphere............................................................................................23 23 Antenna 2 markedly larger than antenna 1, width up to 2x the width of antenna 1 in the thumbed male. Gnathopod 2, propodus of themajorformthumbedmale, thumbtipnotincised (Fig. 60). North Pacific............................... J. kimi n. sp. - Antenna 2 not markedly larger than antenna 1, width up to 1.5x the width of antenna 1 in the thumbed male. Gnathopod 2, propodusof themajorformthumbedmale, thumbtipincised (Figs 37–39). North Atlantic.................. J. pusilla (Sars, 1894), Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 162-163, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288","Heller, C. (1866) Beitrage zur naheren kenntnis der amphipoden des Adriatischen Meeres. Denkschriften. Akademie der Wissenschaften in Wien, Mathematisch-Naturwissenschaftliche Klasse, 26 (2), 1 - 62.","Dana, J. D. (1853) Crustacea. Part II. United States Exploring Expedition, during the years 1838, 1839, 1840, 1841, 1842, under the command of Charles Wilkes. U. S. N. C., 14, 689 - 1618.","Holmes, S. J. (1905) The Amphipoda of southern New England. Bulletin of the United States Bureau of Fisheries, 24, 457 - 529.","Pfeffer, G. (1888) Die krebse von Sud-Georgien nach der ausbeute der Deutschen station 1882 - 83. 2. Die Amphipoden. Hamburg Wissenschafftlichen Anstalten Jahrbuch, 5, 75 - 142. https: // doi. org / 10.5962 / bhl. title. 10084","Montagu, G. (1808) Description of several marine animals found on the south coast of Devonshire. Transactions of the Linnean Society of London, 9, 81 - 114. https: // doi. org / 10.1111 / j. 1096 - 3642.1818. tb 00327. x","Walker, A. O. (1893) Podocerus herdmani, n. sp., In: Herdman, W. A., Sixth annual report of the Liverpool Marine Biology Committee and their biological station at Port Erin. P roceedings and Transactions of the Liverpool Biological Society. The Society, Liverpool, 1893, p. 79.","Vader, W. & Krapp, T. (2005) Crab-associated amphipods from the Falkland Islands (Crustacea, Peracarida). Journal of Natural History, 39, 3075 - 3099. https: // doi. org / 10.1080 / 00222930500218573","Sars, G. O. (1894) Amphipoda. Part XXVII & XXVIII. Podoceridae (concluded), Corophiidae, Cheluridae. An account of the Crustacea of Norway, with short descriptions and figures of all the species, 1, 589 - 628. https: // doi. org / 10.5962 / bhl. title. 1164"]}

Jassa algensis (Nardo, 1847a) Originally named Cancer algensis by Stefano Chiereghin in an unpublished manuscript, this species, from the Venice lagoon, was mentioned in two publications by Nardo in 1847. Nardo (1847a, p. 132) described “... Cancer algensis, Chiereghin, sp.60, fig. 76–79, which has the peculiarity of weaving a garment shaped like a cornucopia on the leaves of the zostera within which it is hidden like the larvae of the Friganee. This was believed by Leach a Podocerus, but should be regarded as a new genus that we named Lusyta, next to Atylus, Leach, and Carapus, Say. ” (translated from Italian). Nardo (1847b) gave a short Latin description of Lusyta algensis which is of no help in deciphering whether this species is in the genus Jassa. Nardo (1869) illustrated Lusyta algensis, showing two figures of its tubes which appeared to be attached to a substrate (one figure life-sized and one enlarged), and two figures of the full body (one figure life-sized and one enlarged). The illustrations are small, but some features are evident. Tubes: the two tubes shown are conical, not cylindrical, and curved. The tubes appear to be open only at one end, with the open head end being 2.5x the width of the closed tail end. The two tubes overlap each other at about 90° with the head of each tube farthest from the other head. The length of the tube in the life-sized illustration is about 7 mm. Body length: the length of the full body in the life-sized illustration is about 6 mm. Antennae 1 and 2: are both slender and about the same length. Gnathopods: the illustration of the full body (enlarged) shows the two gnathopods to be no larger than the pereopods. Illustration of other features, such as the morphology of the third uropod were too small to assist with determining taxonomic status. Nardo’s description of Lusyta algensis sheds further light by stating that “The first two feet are large, equal...” (I primi due piedi sono grossetti, eguali…). Stebbing (1906) listed Lusyta Nardo, 1847a and L. algensis Nardo, 1847a under the title “Gammarideorum genera dubia et species dubiae.” Two features of the illustrations and description in Nardo (1869) suggest that Lusyta algensis is not Jassa: the equally sized gnathopods, and the appearance of the tube. In Jassa, the second gnathopod is so enlarged compared to the first (even in the female and juvenile) that this should be evident both in the description and in the drawings made by Nardo (1869). The tubes are not Jassa -like. Jassa builds a cylindrical tube which is open at both ends, not a curved, conical tube that is open only at one end. Therefore, it is unlikely that Nardo’s Lusyta algensis is in fact Jassa at all. To confirm this is not possible, unfortunately, as most of the Nardo collection has been lost and what is left has no labels (pers. comm. with Roberta Salmaso, Museo Civico di Storia Naturale, Verona, 17 July 2018)., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on page 159, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Nardo, G. D. (1847 a) Prospetto della fauna marina volgare del Veneto Estuario con cenni sulle principali specie commestibili dell'Adriatico, sulle venete pesche, sulle valli, ecc. In: Privil, I. R. (Ed.), Venezia e le Sue Lagune. Vol. 2. G. Antonelli, Venezia, pp. 113 - 156.","Nardo, G. D. (1847 b) Sinonimia moderna delle specie registrate nell' opera intitolata: descrizione de' crostacei, de' testacei e de' pesci che abitano le lagune e golfo Veneto rappresentanti in figure, a chiaro-scuro ed a colori dall' Abate Stefano Chiereghini: Venezia, Ven. Clodiense, applicata per commissione governativa dal Dr. Gio. Domenico Nardo. G. Antonelli, Venezia, 127 pp. https: // doi. org / 10.5962 / bhl. title. 120206","Nardo, G. D. (1869) Annotazioni illustranti cinquantaquattro specie di Crostacei podottalmi, endottalmi e succinatori del Mare Adriatico: Alcune delle quali nuove o male conosciute, accompagnate de trentatre figure litografate, e precedute dall storia della carcinologia Adriatica antica e recente. Memorie del Instituto Veneto, 14, 217 - 340. https: // doi. org / 10.5962 / bhl. title. 120193","Stebbing, T. R. R. (1906) Amphipoda. I. Gammaridea. Das Tierreich, 21, 1 - 806."]}

Jassakimi n. sp. (Table 12, Figs 60–61) Diagnosis. Male: Mandibular palp: article 2, dorsal margin without a fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with a few minute setae along its length; carpus with a single short medial seta at the anterodistal junction of the propodus. Gnathopod 2: basis without a row of long setae along the anterolateral margin (setae minute, << basis width); carpus and propodus, setae on the anterior margin minute (setal length << basis width). Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process underlying about 1/3 of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae in addition to the usual short setae at each dorsolateral cusp. Thumbed male: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmar defining spines not produced on a ledge, minute in large thumbed male (state for small thumbed males unknown). Minor male unknown. Major male, thumb distally rounded with posterior corner more acute than the anterior corner, incised well into the proximal half of the propodus. Dactyl expanded close to the junction with the propodus but not centrally toothed. ......continued on the next page TABLE 12. (Continued) 14 Very large thumbed males may have greatly lengthened second antennae that lack the plumose setae that smaller males possess (Fig. 62) 15 In J. myersi, the setae are sparse, but can be interpreted to be numerous enough to comprise a fringe or not to comprise a fringe. Therefore, in the key to all species, J. myersi has been included twice so that it can be keyed out as either having a fringe or not. Adult female: Unknown. Description. Male, holotype. Length 3.5 mm. Antenna 1: each article with long filter setae on the posterior margin; accessory flagellum 2 articles, the second minute; flagellum 5 articles, the last minute, bearing aesthetascs. Antenna 2: stouter than antenna 1 and overlapped by antenna 1 to 2/3 the length of article 5; without plumose setae on the posterior margin of the peduncle and flagellum; flagellum 3 articles, article 1 65% of flagellum length, article 3, 45% as long as article 3, flagellum articles 2 and 3 bearing curved spines posterodistally. Mandible: palp articles 2 and 3 without dorsal fringe of setae; raker spines 2 right, 3 left. Maxilla 1: palp without setae at the base of article 1, article 2 with 1 row of facial setae; inner plate without setae apparent. Gnathopod 1: coxa produced forward and creased laterally, coxal margins, anterior 60% of dorsal length, ventral margin straight; basis flanged anteriorly, anterior margin without a fringe of long setae (all setae minute), posterior margin without setae; carpus, posterior lobe 40% of anterior margin length, with a single short medial seta at the anterodistal margin; propodus, palm shallowly concave, defined by 2 medial spines, these mid-distant along the palm; dactyl not facially striated. Gnathopod 2: coxa rectangular, coxal margins, anterior 50% and posterior 40% of ventral length, ventral margin slightly wavy; gill present; carpus, posterior lobe without a cluster of setae; propodus, anterior margin without setae proximally, palm with a few plumose setae at the dactyl hinge, defined by a long, slightly sinuous thumb that is rounded at the anterior tip and more squared at the posterior tip, with 1 short palmar defining spine, thumb length 37% of propodus length. Pereopod 3: coxa deepest posteriorly; basis, margins shallowly convex; merus, central setae 45% of article width, article width maximally 75% of length; carpus nearly 100% overlapped by the merus; propodus not posteriorly spinose. Pereopod 4: coxa nearly square; other articles as for pereopod 3. Pereopod 5–7: distal articles slender, propodus not distally expanded, with small spines only anterodistally at the junction of the dactyl; dactyl, posterior (outer) margin not cusped distally, anterior (inner) margin bearing a seta only at the unguis. Pleopods: with 2 peduncular coupling hooks. Uropod 1: peduncle, posteroventral spinous process underlying 37% of the inner ramus, inner and outer rami with 2 and 4 mid-dorsal spines respectively, not terminating in a fringe of cusps ventral to apical spine group. Uropod 2: peduncle, posteroventral spinous process absent. Uropod 3: outer ramus with 1 larger cusp proximal to the basally immersed, dorsally recurved spine and minute cusps around it; inner ramus without a spine mid-dorsally. Telson: tip without apical setae in addition to the single long seta and pair of short plumose setae at each dorsolateral cusp. Condition. Mouthparts, left antenna 1, right antenna 2, left gnathopod 1, right gnathopod 2, pereopods 3–7, pleopods 1–3 and uropods 1–3, left uropod 3 and telson slide mounted. Right antenna 1 article 1, left antenna 2, right gnathopod 1 coxa-ischium, left gnathopod 2, pereopod 5, pleopods and uropods 1 and 2 with the whole body. Missing remainder of right antenna 1 and gnathopod 1 and left pereopods 4, 6 and 7. Type material examined. Holotype, male, 3.5 mm, from a light trap at 4–6 m depth near a breakwater at Impo Port, Yeosu-Si, The Republic of Korea, 34°35′47″N, 127°48′17″E, S.-S. Hong, collector, 23 June 2011. catalogue number: MARBK-115; deposit institution: Marine Amphipoda Resources Bank of Korea (MARBK), Cheonan, South Korea. Etymology. Named in honour of Young-Hyo Kim, who has considerably expanded our knowledge of the biodiversity of Korean amphipods. Remarks. Numerous combinations of non-sexually dimorphic characters serve to distinguish J. kimi from all other species of Jassa. Jassa kimi lacks the fringe of setae on the anterior margin of the gnathopod 2 basis which is distinctive in numerous North Pacific species of Jassa (J. borowskyae, J. carltoni, J. oclairi, J. staudei, J. marmorata, J. slatteryi, and J. morinoi). From the other North Pacific species that also lack this fringe (J. myersi and J. shawi), it can be distinguished by having only a very short seta on the carpus of gnathopod 1 at the anterodistal junction of the propodus (long seta in J. myersi but short in J. shawi). From J. shawi it can be distinguished by the length of the peduncular process underlying the rami of uropod 1. In J. kimi, this process is about one third the length of the longer inner ramus, which is typical of most species of Jassa. In J. shawi, this process is extremely short, appearing absent unless viewed microscopically. When compared with Northern Hemisphere species that are restricted to the Atlantic and adjoining seas (J. falcata, J. herdmani, J. laurieae, J. monodon and J. pusilla), the absence of a setal fringe on gnathopod 2 can be readily used as a distinguishing character as all lack this fringe. These species bear other character states that are not shared with J. kimi. Jassa falcata and J. herdmani possess an extra fringe of setae on the second article of the mandibular palp which is directed dorsally, which J. kimi does not possess. Jassa monodon has a distinctive cluster of setae at the apex of the telson, which J. kimi lacks. Jassa laurieae and J. pusilla lack the carpal seta on gnathopod 1 that J. kimi possesses. The male dimorphism also differs. Jassa kimi does not bear plumose setae on antenna 2 while J. laurieae does. The thumb shape of the major male distinguishes J. kimi from J. pusilla: very long and slightly sinous in J. kimi with a squared end, while in J. pusilla the thumb is shorter and the tip incised. For Southern Hemisphere species, the fringe of spine-like setae along the anterior margin of the basis of gnathopod 1, long carpal seta(e) on gnathopod 1 and/or the prehensile pereopods 5–7 will separate J. kimi from J. alonsoae, J. fenwicki, J. hartmannae, J. ingens, J. justi, J. kjetilanna and J. thurstoni. That leaves J. gruneri, which is less easy to compare as the thumbed male is unknown for J. gruneri but known for J. kimi and the female and juvenile are known for J. gruneri but unknown for J. kimi. When the female and juvenile male of J. kimi are found, it is likely that the palm of the gnathopod 2 will be concave, which is a characteristic of most Northern Hemisphere species of Jassa, while females and juvenile males of Southern Hemisphere species typically have sinuous palms (as does J. gruneri). Other characteristics may also distinguish these species: e.g., fewer articles in the antenna 2 flagellum in J. kimi than J. gruneri and generally more slender and elongated mouthparts in J. kimi than J. gruneri., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 102-108, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622

Jassashawi Conlan, 1990 (Table 12, Figs 83–84) Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin without a fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with one short seta at distal angle; carpus with a short seta medially, at the anterodistal junction of the propodus (seta length Gnathopod 2: basis without a row of setae along the anterolateral margin; carpus and propodus, setae on the anterior margin short and simple (setal length Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process very short, underlying only about 10% of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae (only the usual short setae at each dorsolateral cusp). Thumbed male: unknown. Adult female: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palm concave, palmar defining angle acute. Remarks. Conlan (1990) was in error about the absence of a seta at the anterodistal junction of carpus with the propodus on gnathopod 1. There is one present slightly medially (Fig. 83). The seta is short and difficult to see but present in both sexes. Only 2 subadult males, 2 adult females and 1 immature were available for study so variation and the appearance of the thumbed adult male could not be determined., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 131-133, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288"]}

Jassaoclairi Conlan, 1990 (Table 12, Figs 62–64) Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin witha fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with only a few short setae distally; carpus with a single or small cluster of long setae at the anterodistal junction of the propodus (setae 40-50% of anterior margin length and slightly lateral). Gnathopod 2: basis with a row of long plumose setae along the anterolateral margin (setae 75% of article width); carpus and propodus, setae on the anterior margin short and plumose (setal length Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process underlying about 1/3 of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae (only the usual short setae at each dorsolateral cusp). Thumbed male: Antenna 2: large individuals nearly asetose, without plumose setae on the flagellum and peduncular article 5 (which are present in smaller males). Gnathopod 2: propodus, palmar defining spines not produced on a ledge, present in small thumbed males but absent in large thumbed males. In minor males, the thumb is distally squared, short relative to body length and located on the distal half of the propodus. The dactyl is centrally toothed on the inner margin. In the major form male, the thumb is distally squared, and originates more centrally on the propodus. The dactyl is expanded close to the junction with the propodus but is not centrally toothed. Adult female: Antenna 2: with abundant plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palm concave, palmar defining angle acute. Remarks. Only one major form male was available for study. Although larger in body size than the minor form adult males, its thumb was relatively short (Fig. 63). However, its second antennae were substantially longer than in the juvenile or female and lacked their plumosity on the peduncle article 5 and flagellum. This is the largest of the Northern Hemisphere species of Jassa and also the most plumose, with plumose setae occurring on the antennae 1 and 2, gnathopod 2 and pereopods 5–7. It is only known from Alaska and northern British Columbia (Fig. 10). This is the only Pacific species known to have the dorsal fringe of setae on article 2 of the mandibular palp. It shares this character state with the European J. falcata and J. herdmani. All other species lack this fringe. This is the only Pacific species known to have the dorsal fringe of setae on article 2 of the mandibular palp. It shares this character state with the European J. falcata and J. herdmani. All other species lack this fringe., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on page 108, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288"]}

Jassagruneri Conlan, 1990 (Table 13, Figs 102–103) Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin without a fringe of setae. Maxilla 1: without a cluster of setae at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with only a few short setae distally; carpus without a single or small cluster of short setae at the anterodistal junction of the propodus. Gnathopod 2: basis with a few or a full row of setae along the anterolateral margin (setal lengths 50% of the basis width); carpus and propodus, setae on the anterior margin short and simple (setal length Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process underlying about 40% of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae (only the usual short setae at each dorsolateral cusp). Thumbed male: unknown. Adult female: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmsinuous. Remarks. This is a small-bodied species with the juvenile male holotype 2.1 mm and the adult female allotype 3.2 mm (Conlan 1990). It is part of the Southern Hemisphere sinuous-palmed group, keying closest to J. thurstoni. Jassa gruneri differs in the lack of a seta on the carpus of gnathopod 1 at the anterodistal junction of the propodus (present in J. thurstoni) and in the presence of a row of setae on the basis of gnathopod 2 (absent in J. thurstoni). This row is more pronounced in the female allotype than the juvenile male holotype (Fig. 102). Currently it is only known from Tasmania and New Zealand. The New Zealand specimen (Fig. 12) is a juvenile male and was found in a collection in Lyttelton harbour described by Chilton (1884). In this same collection is a specimen used by Chilton to describe his new species Podocerus latipes Chilton, 1884, which was synonymized by Stebbing (1906) under Jassa frequens (Chilton, 1883) and later transfered to Ventojassa (Conlan 2021)., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 156-158, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288","Chilton, C. (1884) Additions to the sessile-eyed Crustacea of New Zealand. Transactions and Proceedings of the New Zealand Institute, 16, 249 - 265.","Stebbing, T. R. R. (1906) Amphipoda. I. Gammaridea. Das Tierreich, 21, 1 - 806.","Chilton, C. (1883) Further additions to our knowledge of the New Zealand Crustacea. Transactions and Proceedings of the New Zealand Institute, 15, 69 - 86.","Conlan, K. E. (2021) New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa, 4921 (1), 001 - 072. https: // doi. org / 10.11646 / zootaxa. 4921.1.1"]}

Jassamonodon (Heller, 1866) ( Table 11, Figs 56–59) Podocerus monodon Heller, 1866, pp. 45–46, plate IV, figs. 4, 5; not J. falcata: Krapp-Schickel (1974), p. 344. Diagnosis. Mandibular palp: article 2, dorsal margin without a fringeof setae. Maxilla 1: state unknown. Gnathopod 1: basis, anterolateral margin without a setal fringe along its length; carpus without a seta or cluster of setae at the anterodistal junction of the propodus. Gnathopod 2: basis with 5–7 widely spaced setae along the anterolateral margin (setal length 1/2 to 2/3 the width of the basis); carpus and propodus, setae on the anterior margin short and simple (setal length Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process underlying about 1/3 of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip with 1–2 apical setae in addition to the usual short setae at each dorsolateral cusp. Condition. Without left gnathopod 1, right pereopods 5–7 and left pereopod 5. Right antennae 1 and 2, left pereopods 3, 4 and 7 broken from the animal but present in the vial. Thumbed male: Antenna 2: missing (subadult, peduncular article 5 with long filter setae; flagellum with short brush setae (not plumose setae)). Gnathopod 2: propodus, palmar defining spines absent in the major form, thumb long, more than half the length of the propodus and distally acute. Dactyl expanded close to the junction with the propodus but not centrally toothed. Minor form unknown. Condition. Without right and left antennae 1 and 2 and pereopods 5–7. Adult female: unknown. Remarks. Jassa monodon was first described by Heller (1866) as Podocerus monodon, based on a subadult male specimen collected at Lesina (Hvar, Croatia). No information on depth or substrate was given. This specimen is in the crustacean collection of the Naturhistorisches Museum Wien (NHMW 20619) and was examined by one of us (KC) in November 2018. Krapp-Schickel (1974) had previously examined this specimen and called it a female Jassa falcata. Asecond specimen of Jassa monodon (NHMW 20621) was also found in Heller’s collection from Lesina and named Podocerus pulchellus in Heller (1866) and Krapp-Schickel (1974). This specimen is a major form thumbed male. These are the only two specimens known for this species. Due to their type status and fragility, the specimens could not be measured for body length or dissected for line drawing. Heller (1866) recorded the length of the holotype subadult male as 5 mm. The length of the major form adult male was not recorded. Jassa monodon has a unique combination of diagnostic characters (Table 11). Other species that currently occur in the vicinity of the type locality for Jassa monodon are J. marmorata, J. slatteryi and J. morinoi (Figs 1–6, 9). The European J. pusilla and J. falcata are not known to occur in the Mediterranean Sea. The European J. herdmani has been found in the western part of the Mediterranean Sea but not as far east as the Adriatic, where J. monodon was collected. Tables 10 and 11 show the key distinguishing characters for these species. Possibly the “ Podocerus falcatus ” described from Trieste, Italy by Nebeski (1880) was J. monodon mixed with J. marmorata. In interpreting this study, Sexton and Reid (1951) suggested that Nebeski (1880) was dealing with both a “Broad-form” and a ʺNarrow-form”. Conlan (1990) identified Sexton and Reid’s Broad-form as J. marmorata and their Narrow-form as being J. falcata or J. herdmani, but did not know of J. monodon ’s characteristics at the time. Both J. marmorata and J. monodon were known from the vicinity of Trieste in the 19 th century (Table 3, Figs 1 and 9)., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 97-102, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Heller, C. (1866) Beitrage zur naheren kenntnis der amphipoden des Adriatischen Meeres. Denkschriften. Akademie der Wissenschaften in Wien, Mathematisch-Naturwissenschaftliche Klasse, 26 (2), 1 - 62.","Krapp-Schickel, G. (1974) Camill Hellers Sammlung adriatischer Amphipoden- 1866 und heute. Annalen des Naturhistorischen Museums in Wien, 78, 319 - 379.","Nebeski, O. (1880) Beitrage zur Kenntniss der Amphipoden der Adria. In: Claus, C. (Ed.), Arbeiten aus dem Zoologischen Institute Der Universitat Wien und der Zoologischen Station in Triest. Vol. 3. Alfred Holder, Wien, pp. 1 - 52.","Sexton, E. W. & Reid, D. M. (1951) The life-history of the multiform species Jassa falcata (Montagu) (Crustacea Amphipoda) with a review of the bibliography of the species. Journal of the Linnean Society of London, Zoology, 42, 283, 29 - 91. https: // doi. org / 10.1111 / j. 1096 - 3642.1951. tb 01852. x","Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288"]}

Jassakjetilanna Vader & Krapp, 2005 (Table 13, Figs 96–98) Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin without a fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with a few short setae along its length; carpus with a very short seta at the anterodistal junction of the propodus (seta about 10% of anterior margin length and slightly lateral). Gnathopod 2: basis with a row of short setae along the anterolateral margin (setal lengths Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process underlying about 1/3 of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae (only the usual short setae at each dorsolateral cusp). Thumbed male: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmar defining spines produced on a ledge in both small and large thumbed males. In minor males, the thumb is distally acute, short relative to body length and located on the distal half of the propodus. The dactyl is not centrally toothed. In major males, the thumb is also acute, relatively short, and on the proximal half of the propodus. The dactyl is shallowly expanded close to the junction with the propodus but is not centrally toothed. Adult female: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palm sinuous; dactyl, inner margin evenly curved, tip fitting into depression between palmar angle and defining spines. Remarks. Known only from the Falkland Islands, this species bears the characteristics of the genus Jassa (antennal setation, strong mandibular palp, gnathopod 2 palm defined by a cluster of spines, terminal male’s thumb produced distally to the spines; pereopod 3 and 4 merus anteriorly produced over the carpus). Specimens collected on 29 October 2003 by A. and W. Vader from the lithodid crab Paralomis granulosa (Hombron & Jacquinot, 1846) at 20–30 m depth in Choiseul Sound, East Falkland, were borrowed from Tromsø Museum, Norway (TSV Cr 19054). The collection consisted of 3 major form thumbed males, 3 subadult (or near-subadult nonthumbed males), 5 adult females (2 ovigerous) and 14 juveniles. Representatives of each group were illustrated (Figs 96–98). Although Vader & Krapp (2005) thoroughly illustrated the types, which were also collected from Choiseul Sound, there was some minor disagreement between the types and the specimens examined, as follows. Maxilla 2: The inner ramus is an extension of the base, not segmented as illustrated by Vader & Krapp (2005). Gnathopod 1: The cluster of setae at the anterodistal junction of the carpus and propodus, stated as present in Vader & Krapp’s (2005) description but absent in the specimens they illustrated, are confirmed present in the specimens examined herein (single, slightly lateral seta in the specimens examined). Gnathopod 2: Subadult males have a small ‘pre-thumb’ (Fig. 97), but the juvenile male gnathopod 2 illustrated by Vader & Krapp (2005) has too large a thumb to be subadult. Instead, it is likely a ‘minor form’ adult. The larger thumbed gnathopod 2 illustrated by Vader & Krapp (2005) is not ‘hyperadult’, but resembles that of a ‘major form’ adult male (Conlan 1990). Uropod 1: The interramal spine that projects underneath the rami is not lateral as illustrated. Uropod 3: The apparent lack of the characteristic pair of cusps proximal to the curved embedded spine at the tip of the outer ramus were present in the specimens examined herein. No conclusions could be drawn on the variation of thumb size relative to body size as only three thumbed males were available for measurement. In comparison with other Southern Hemisphere species of Jassa, Vader & Krapp (2005) considered the relationship of J. kjetilanna to J. thurstoni and J. alonsoae due to their co-occurrence in the Falkland Islands. Jassa alonsoae has many morphological features that are not shared with J. kjetilanna, but J. thurstoni is more similar if intraspecific variation is taken into consideration. It requires the use of sex- and ageinvariant characters to differentiate species of Jassa because their morphology varies so much with age, size and sex. Using only key characters, J. kjetilanna and J. thurstoni are separable by the length of the seta or setal cluster on the carpus at the anterodistal junction of the propodus. This is minute in kjetilanna (length ~10% of the anterior margin of the carpus) and easily overlooked, but longer in J. thurstoni (~25% of the length of the carpus). This setal length is invariant in other species of Jassa, so the length difference between J. kjetilanna and J. thurstoni is considered significant enough to indicate that these species are morphologically distinct. There are also shape and size differences: slender, long antennae in J. thurstoni, shorter, stouter antennae in J. kjetilanna; anteriorly produced coxa 1 in J. thurstoni adult male and less produced coxa 1 in J. kjetilanna; differently shaped thumbs in the adult males with tendency to pronunciation of the defining spines in J. kjetilannna and loss in J. thurstoni; and similarly sized pereopods 5–7 in J. kjetilanna with relatively strong spines at the anterodistal end of the propodus compared to increasingly longer pereopods 5–7 in J. thurstoni with slender, seta-like spines anterodistally on the propodus., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 148-152, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Vader, W. & Krapp, T. (2005) Crab-associated amphipods from the Falkland Islands (Crustacea, Peracarida). Journal of Natural History, 39, 3075 - 3099. https: // doi. org / 10.1080 / 00222930500218573","Hombron, J. B. & Jacquinot, H. (1846) Crustaces. In: Voyage au pole sud et dans l'oceanie sur les corvettes l'Astrolabe et la Zelee pendant les annees 1837 - 1838 - 1839 - 1840 sous le commandement de M. Dumont-d'Urville capitaine de vaisseau publie par ordre du commandant de la Zelee. Zoologie. Atlas. Gide, Paris, pl. 8.","Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288"]}

Jassa calcaratus (Rathke, 1843) In documenting the fauna of Norway, Rathke (1843) described and figured a new species which he had collected from seaweed at Kristiansund, Norway. Named Podocerus calcaratus, his illustration of the male’s long-thumbed gnathopod 2 indicates that it is probably Jassa falcata. Rathke (1843) indicated that P. calcaratus was close to, but different from P. pulchellus (now Jassa falcata) but did not state why. Bate (1862) disagreed and synonymized P. calcaratus under P. pulchellus (now Jassa falcata). Sars (1894) listed P. calcaratus as a synonym of P. falcatus (now Jassa falcata), saying that “The P. calcaratus of Rathke is undoubtedly the adult male of this species...” One large male specimen, collected at Tromsø, Norway, and identified as Podocerus calcaratus by Danielsen, (not type), was lent by the Zoological Museum, Bergen, Norway (ZMUB 2832) for this study. The vial held a secondary label, Jassa pulchella. This specimen was clearly a major form male J. falcata. Although the whereabouts of the type specimens are unknown, it is clear from Rathke’s (1843) description, illustrations and collection location that his P. calcaratus is indeed J. falcata (Montagu, 1808). Therefore, J. calcaratus is synonymized with J. falcata., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on page 160, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Rathke, H. (1843) Beitrage zur fauna Norwegens. Nova Acta Academiae Caesareae Leopoldino-Carolinae Naturae Curiosorum, Breslau & Bonn, 20, 1 - 264. https: // doi. org / 10.5962 / bhl. title. 120119","Bate, C. S. (1862) Catalogue of the specimens of amphipodous Crustacea in the collection of the British Museum. Taylor & Francis, London, 399 pp.","Sars, G. O. (1894) Amphipoda. Part XXVII & XXVIII. Podoceridae (concluded), Corophiidae, Cheluridae. An account of the Crustacea of Norway, with short descriptions and figures of all the species, 1, 589 - 628. https: // doi. org / 10.5962 / bhl. title. 1164","Montagu, G. (1808) Description of several marine animals found on the south coast of Devonshire. Transactions of the Linnean Society of London, 9, 81 - 114. https: // doi. org / 10.1111 / j. 1096 - 3642.1818. tb 00327. x"]}

Jassa orientalis (Dana, 1852a) Dana (1852a) originally named this species Gammarus orientalis, changing it to Cratophium orientale the following year (Dana 1853). Dana (1853) based his description of this species on a single specimen captured “From the sea, off the eastern entrance of the Straits of Sunda. Collected, March 4, 1842.” This was during the United States Exploring Expedition led by Charles Wilkes (1838–1842). Bate (1862) transferred it to the genus Podocerus. Della Valle (1893) synonymized it with P. falcatus (now Jassa falcata). As noted in Conlan (1990), the type specimens were lost (confirmed absent from the collection of the Smithsonian Institution, National Museum of Natural History, 13 May 2019 by Karen Reed, Museum Specialist, Department of Invertebrate Zoology). Dana’s (1853) Plate 56, Fig. 3, showing the whole body and gnathopod 2 of a female or non-thumbed male, indicate that the specimen is indeed a Jassa, but the species cannot be determined from the description and illustration. Since Jassa as a genus is not known from Indonesia, it is possible that this specimen was a species of Jassa that had been displaced from one of Wilkes’ six ships, all of which may have been fouled by Jassa, as occurred in the Challenger Expedition (see Results: Distribution). The ships used by the Wilkes expedition departed from Hampton Roads, Virginia in 1838 (Philbrick 2004). Jassa marmorata has been known from this coast since 1883 (Table 3) and currently it is the only species of Jassa known from the Virginia coast (Figs 1–2), suggesting that the ships were fouled by this species and subsequently dispersed to temperate coasts of South America, Australia and the Pacific U.S. that were visited by the Wilkes expedition. Therefore, it is possible that Cratophium orientale is synonymous with Jassa marmorata but the loss of the type specimens cannot make this unequivocal., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on page 161, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Dana, J. D. (1852 a) Conspectus crustaceorum quae in orbis terrarum circumnavigatione, Carolo Wilkes e classe Reipublicae Faederatae Duce, lexit et descripsit Jacobus D. Dana, Pars III (Amphipoda n ° 1). Proceedings of the American Academy of Arts and Sciences, 2, 201 - 220.","Dana, J. D. (1853) Crustacea. Part II. United States Exploring Expedition, during the years 1838, 1839, 1840, 1841, 1842, under the command of Charles Wilkes. U. S. N. C., 14, 689 - 1618.","Bate, C. S. (1862) Catalogue of the specimens of amphipodous Crustacea in the collection of the British Museum. Taylor & Francis, London, 399 pp.","Della Valle, A. (1893) Fauna und flora des Golfes von Neapel und der angrenzenden meeres-abschnitte herausgeben von der zoologischen station zu Neapel. 20. Monographie: Gammarini. R. Friedlander & Sohn, Berlin, 948 pp.","Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288","Philbrick, N. (2004) Sea of Glory: America's Voyage of Discovery: the US Exploring Expedition, 1838 - 1842. Penguin, New York, 451 pp."]}

Jassa marmorata Holmes, 1905 (Table 10, Figs 15–21) Synonyms: see Conlan (1990). Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin without a fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with a few short setae along its length; carpus with a (usually) single or a small cluster of short setae at the anterodistal junction of the propodus (setae Gnathopod 2: basis witha row of closely spaced setae along the anterolateral margin (at least some setal lengths>40% of the basis width); carpus and propodus, setae on the anterior margin short and simple (setal length Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process underlying about 1/3 of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae (only the usual short setae at each dorsolateral cusp). Thumbed male: Antenna 2: large individuals with plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmar defining spines not produced on a ledge, present in small thumbed males but absent in large thumbed males. In minor males, the thumb is distally acute, short relative to body length and located on the distal half of the propodus. The dactyl is not centrally toothed. In major males, the thumb is distally squared, longer relative to body length and on the proximal half of the propodus. The dactyl is expanded close to the junction with the propodus but is not centrally toothed. Adult female: Antenna 2: large animals with plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palm concave, palmar defining angle acute. Remarks. Jassa marmorata has often been mis-identified as J. falcata in the past (Conlan 1990). Sexton and Reid (1951) studied the development of J. falcata and their J. falcata “broad form” is in fact J. marmorata. The transformation of four males from non-thumbed to thumbed state in aquarium cultured specimens is reproduced in Fig. 18 from Sexton and Reid’s (1951) plates. This shows that some subadult males have a small “pre-thumb” in the palm of gnathopod 2 (Figs 8a, b, 14 d, e and 18) while others do not (Figs 9a, 10a and 18). The appearance of a pre-thumb appears to occur only in larger juveniles (Fig. 16). Fig. 18 also shows that while the palmar defining spines are retained in small thumbed males, they are lost in large thumbed males. Sexton and Reid (1951) produced intersexes with a short, narrow thumb and small, setose brood plates by inbreeding siblings generated by a pair collected in the wild. Although the intersexes mated with female siblings, the offspring did not survive to maturity. Two intersexes and an ovigerous female were also found in NMNH 148787, 3–38, taken in a dredge at 18–27 m over sandy, weedy bottom inside the northern point of entrance to Magdalena Bay, Lower California, on July 18, 1938. Both intersexes had all the distinguishing features of J. marmorata but short thumbs on the second gnathopods and a toothed dactyl similar to that in minor forms of J. falcata and J. staudei. Jassa marmorata is morphologically similar to J. valida and the two overlap in distribution at the junction of their ranges in North Carolina, which is a biogeographic break for many species (Pappalardo et al. 2015). Distributions listed in OBIS for J. marmorata for the coasts of the US south of North Carolina, including the Gulf of Mexico require confirmation because they may be for mis-identified J. valida. Asimilar southerly range into the Gulf of Mexico and on the coasts of Cuba and the Bahamas listed by Conlan (1990) may also be for J. valida, not J. marmorata. It is possible that some or all records of J. marmorata on the coasts of Uruguay and Argentina described by Alonso de Pina (2005) are unrecognized J. valida, since J. valida is already known from this coast. The most dependable character to distinguish the two species of any size is the lack of apical setae on the telson of J. marmorata and presence in J. valida. However, viewing this character requires moving the third uropods out of the way of the telson (this can be done by holding the animal on its side and bending the uropods downwards with a fine needle). It also requires that the usual pair of setae at the the telson knobs, which project dorso-distally, are not confused with the apical setae, which project distally. The other diagnostic characters of J. marmorata, which are easier to view, can be used for adult and subadult specimens. Due to the availability of a large number of specimens from the neotype population (162 adult and juvenile males measured for Fig. 16), there were 10 major form and 17 minor form males that overlapped in body length (4.08–4.67 mm) for comparison of thumb length relative to body length. A Kruskal-Wallis test indicated that thumb lengthwassignificantly longerinthe major thanminorforms of thissizerange ( HKW = 4.017, p t -test, t = 3.458, p = 0.001, n = 27 major forms and 12 juveniles) (Fig. 17). Similarly, the juvenile males had a significantly longer propodus than the adult females of thesamebodylengthrange (3.25–5.33 mm) ( HKW = 2.195, p n = 15 and 0.88 mm for adult females, n = 8) (Fig. 17). The SEM image of the telson (Fig. 20) shows paired short plumose setae to either side of the telson nubs and associated long, erect seta dorsal to each nub. The nub magnifications show that the nubs are actually cusped and the erect setae are ringed at their tips by rows of scales. Presumably, the erect setae have a sensory function, perhaps for position within the tube and the cusped nubs may assist with gaining a purchase within the tube. Possibly the plumose setae are mechanoreceptive as well (Kauffmann 1994). Only two specimens of the ~25,000 specimens of Jassa examined were found to be densely coated in epibionts (Fig. 21). All other specimens appeared to be clean or with much smaller and sparser epibionts. However, specimens collected in Helgoland Harbour (Germany) often were coated with epibionts. Both of the densely coated specimens were large, major form thumbed males and the epibionts were algal in appearance (green Enteromorpha -like algae or filamentous as in Fig. 21). The specimen bearing a green algal coat (found among algae on a floating dock in Adelaide, Australia) was so densely covered that it was barely recognizable. The specimen shown in Fig. 21 was from a fouling community on a natural gas platform in Morecambe Bay, UK In both specimens, the epibionts were concentrated on the anterior of the body, coating the dorsum and second gnathopods. This pattern suggests that the animals were partially tubicolous during the time of infestation. Movement within the tube may have prevented epibiont accumulation on the posterior part of the body. The cleaning action of the first gnathopods may have prevented epibiont growth on body parts within reach, such as the antennae. That epibiont growth was able to establish in such quantity on these males suggests that the males had not molted for some time, and that they were senescent and not able to prevent epibiont settlement. There are four corrections to Conlan (1990): (1) Sexton and Reid (1951) Plate 12, 5a–5f should be added to p. 2053; (2) specimens from Crooke’s Point, New York (p. 2054) are from Staten Island, New York, not the Hudson River (S. Grabe, pers. comm., date not recorded); (3) J. marmorata is not yet known from Alaska; an Alaskan specimen attributed to J. marmorata in Conlan (1990) and repeated by Fofonoff et al. (2019) is actually the indigenous J. staudei (specimen re-examined May 23, 2018); (4) Conlan (1990) did not recognize that “ J. marmorata ” in the Gulf of Mexico and on the US Atlantic coast from Florida to North Carolina were more likely to be J. valida than J. marmorata, although the two species could overlap in range (Figs 1, 2, 7, 8). Therefore, the identification of specimens from these coasts are suspect. This has been rectified for collections at the Canadian Museum of Nature (CMN) but not elsewhere (see Remarks section for J. valida). Similarly, “ J. marmorata ” found in the southwestern Gulf of Mexico with J. valida by Winfield et al. (2021) are possibly also J. valida as the specimens they reported were very small (2.36 ± 0.38 mm body length, n = 5) and therefore likely difficult to view the diagnostic terminal seta(e) on the telson that denotes the identification as J. valida (Supplementary Data File S1). It was not possible to borrow the specimens to confirm the identification as the museum collections were closed due to the COVID-19 pandemic. Aloan that came after Conlan (1990) is a sample of J. marmorata in a collection taken at 13 m depth on a shellmuddy-sand substrate offshore of S„o Paulo, Brazil in 1963. This is the earliest known collection of J. marmorata on the Atlantic coast of South America (Table 3). It is possible that this sample was contaminated by J. marmorata fouling the ship. Ascraping of a small ship in 1985 in this area found J. marmorata on the hull. Astudy of amphipods inhabiting the moderately polluted Newport Bay in 1954 (now part of Los Angeles) found “ J. falcata ” in small numbers compared to the large populations on pilings in Los Angeles Harbor (Barnard and Reish 1959). Although not seen, these specimens may be J. marmorata, since it has been found exclusively on other human-modified habitats on the Pacific coast of North America (this study and Fofonoff 2019). Jassa marmorata has been collected in California as far back as 1931 (Table 3)., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 46-53, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Holmes, S. J. (1905) The Amphipoda of southern New England. Bulletin of the United States Bureau of Fisheries, 24, 457 - 529.","Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288","Sexton, E. W. & Reid, D. M. (1951) The life-history of the multiform species Jassa falcata (Montagu) (Crustacea Amphipoda) with a review of the bibliography of the species. Journal of the Linnean Society of London, Zoology, 42, 283, 29 - 91. https: // doi. org / 10.1111 / j. 1096 - 3642.1951. tb 01852. x","Pappalardo, P., Pringle, J. M., Wares, J. P. & Byers, J. E. (2015) The location, strength, and mechanisms behind marine biogeographic boundaries of the east coast of North America. Ecography, 38 (7), 722 - 731. https: // doi. org / 10.1111 / ecog. 01135","Alonso de Pina, G. M. (2005) A new species of Notopoma Lowry & Barents, 1996, and a new record of Jassa marmorata Holmes, 1905, from the southwestern Atlantic (Amphipoda: Corophiidea: Ischyroceridae). Proceedings of the Biological Society of Washington, 118, 528 - 538. https: // doi. org / 10.2988 / 0006 - 324 X (2005) 118 [528: ANSONL] 2.0. CO; 2","Fofonoff, P. W., Ruiz, G. M., Steves, B., Simkanin, C. & Carlton, J. T. (2019) National exotic marine and estuarine species information system. Marine Invasions Lab, Smithsonian Environmental Research Center, Edgewater, Maryland. Available from: http: // invasions. si. edu / nemesis / (accessed 4 October 2019)","Winfield I., Herrera-Dorantes M. T. & Ardisson, P. L. (2021) Distribution of genus Jassa (Amphipoda, Ischyroceridae) in the Bay of Campeche, SW Gulf of Mexico, with a description of a new deepwater species. Bulletin of Marine Science, 97 (1), 219 - 236. https: // doi. org / 10.5343 / bms. 2020.0042","Barnard, J. L. & Reish, D. J. (1959) Ecology of Amphipoda and Polychaeta of Newport Bay, California. Allan Hancock Foundation Publications, Occasional Paper, 21, 1 - 106."]}

Jassaherdmani Walker, 1893 (Table 11, Figs 48–53) Synonyms: see Conlan (1990). Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin witha fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with a few very short setae; carpus without a single or small cluster of setae at the anterodistal junction of the propodus. Gnathopod 2: basis with a few minute setae along the anterolateral margin but without long filter setae (setal lengths Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process underlying about 40% of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae, only the usual short setae at each dorsolateral cusp. Thumbed male: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmar defining spines absent except in small males. Thumb distally acute or squared in minor males and squared in major males. Dactyl centrally toothed in minor forms and shallowly expanded proximally in major forms. Adult female: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palm concave, palmar defining angle acute, distal to but close to the defining spines. Remarks. The neotype (Fig. 48), which was erected by Conlan (1990), is a minor form male with short thumb and toothed dactyl, corresponding with “The specimen originally described as P. herdmani, taken by Professor Herdman from a Compound Ascidian off the Island of Bute...” (Walker 1911, p. 71). Jassa herdmani naturally co-occurs with J. falcata and J. marmorata but the three species differ in microhabitat selection, life cycle, reproduction and temperature adaptation (Beermann & Franke 2012; Beermann & Purz 2013). The identity of the three species can be easily confused, especially when small (Sexton & Reid 1951; Conlan 1990). Conlan (1990) outlines how these can be distinguished on the basis of the antenna 2 plumosity, gnathopod 1 and 2 shape and setation and uropod 3 inner ramus spination. Fig. 49 shows the thumb length relationships among specimens collected later by D.M. Reid from Plymouth Harbour on April 14, 1937. Although the collection was small, different morphologies of the minor and major form adult male are evident and the subadult male has a small pre-thumb before it molts into a (probably major form) thumbed male, judging by its large body length. Sexton and Reid (1951) called this pre-thumbed stage of the subadult male the “cut-across stage”. Reproductions of Sexton and Reid’s (1951) figures that are confirmed J. herdmani are shown in Figs 50 and 51. These specimens were collected in Plymouth Harbour at various dates between 1928 and 1930 and kept in aquaria, where changes in their morphologies were recorded as they molted. The transformation of the subadult male 13D to major form thumbed male 13E (their labels) is shown in Fig. 51. They mistook these specimens as J. falcata, calling them the ʺNarrow Form” of J. falcata. The females of the two species also differ subtly, with the palmar angle of the gnathopod 2 propodus more bulbous and farther from the defining spines in J. falcata (Fig. 44) than in J. herdmani (Figs 51, 52). The dactyl toothing appears to vary with thumb length. In the minor form with short, distal thumb (Figs 48 and 49), the dactyl tooth is pronounced. In the major form with longer, more proximal thumb (Fig. 51, specimen 13E), the dactyl tooth is shallower and more proximal. In the large major form with a long, proximal thumb (Figs 48, 49 and 51, specimen 1), the dactyl is expanded proximally, rather than more centrally toothed. One of the key features for J. herdmani is the cluster of setae on the dorsal margin of the mandibular palp article 2. This is shown in Fig. 53. One specimen noted in Lobo et al. (2017) as being Jassa sp. is J. herdmani (specimen examined 4 March 2019). This is likely the Jassa sp. in their Fig. 2 that matches other specimens of J. herdmani from the North Sea in their CO1-5P sequence. The finding of a single juvenile female in coral rubble at Aqaba, Jordan by Lyons and Myers (1991) (identification confirmed) places the range of J. herdmani far outside the northeast Atlantic coast and western Mediterranean Sea where it has most often been collected (Fig. 9). This suggests that J. herdmani may have a propensity for exotic dispersal similar to J. marmorata, J. slatteryi and J. morinoi. It commonly fouls offshore structures in the North Sea (oil and gas platforms, wind turbines and shipwrecks) (Coolen et al. 2018; Luttikhuizen et al. 2019) which are thought to supply extended shallow, hard substrate and it has been collected on buoys (Sexton and Reid 1951) and boat bottoms as far back as 1890 (NHM 1925.9.8:1602). The Suez Canal is a transportation route for many exotic species, resulting in the eastern Mediterranean having many more introductions than the western Mediterranean (Galil et al. 2015). Lyons and Myers (1991) suggest that J. herdmani may be on the Atlantic coast of central Africa as well. This is based on literature reports that have not been confirmed by examination of specimens. Possibly these reports refer to J. marmorata or J. morinoi which are confirmed there (Figs 1, 2, 5 and 6)., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 87-92, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Walker, A. O. (1893) Podocerus herdmani, n. sp., In: Herdman, W. A., Sixth annual report of the Liverpool Marine Biology Committee and their biological station at Port Erin. P roceedings and Transactions of the Liverpool Biological Society. The Society, Liverpool, 1893, p. 79.","Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288","Walker, A. O. (1911) Notes on Jassa falcata (Mont.). Transactions of the Liverpool Biological Society, 25, 67 - 72.","Beermann, J. & Franke, H. - D. (2012) Differences in resource utilization and behaviour between coexisting Jassa species (Crustacea, Amphipoda). Marine Biology, 159 (5), 951 - 957. https: // doi. org / 10.1007 / s 00227 - 011 - 1872 - 7","Beermann, J. & Purz, A. K. (2013) Comparison of life history parameters in coexisting species of the genus J assa (Amphipoda, Ischyroceridae). Journal of Crustacean Biology, 33 (6), 784 - 792. https: // doi. org / 10.1163 / 1937240 X- 00002190","Sexton, E. W. & Reid, D. M. (1951) The life-history of the multiform species Jassa falcata (Montagu) (Crustacea Amphipoda) with a review of the bibliography of the species. Journal of the Linnean Society of London, Zoology, 42, 283, 29 - 91. https: // doi. org / 10.1111 / j. 1096 - 3642.1951. tb 01852. x","Lobo, J., Ferreira, M. S., Antunes, I. C., Teixeira, M. A. L., Borges, L. M. S., Sousa, R., Gomes, P. A., Costa, M. H., Cunha, M. R. & Costa, F. O. (2017) Contrasting morphological and DNA barcode-suggested species boundaries among shallow-water amphipod fauna from the southern European Atlantic coast. Genome, 60, 147 - 157. https: // doi. org / 10.1139 / gen- 2016 - 0009","Lyons, J. & Myers, A. A. (1991) Amphipoda Gammaridea from coral rubble in the Gulf of Aqaba, Red Sea: families Dexaminidae, Eusiridae, Isaeidae, Ischyroceridae, Leucothoidae, Liljeborgiidae and Lysianassidae. Journal of Natural History, 25, 597 - 621. https: // doi. org / 10.1080 / 00222939100770381","Coolen, J. W., Van Der Weide, B., Cuperus, J., Blomberg, M., Van Moorsel, G. W., Faasse, M. A., Bos, O. G., Degraer, S. & Lindeboom, H. J. (2018) Benthic biodiversity on old platforms, young wind farms, and rocky reefs. ICES Journal of Marine Science, 77 (3), 1250 - 1265. https: // doi. org / 10.1093 / icesjms / fsy 092","Luttikhuizen, P. C., Beermann, J., Crooijmans, R. P. M. A., Jak, R. G. & Coolen, J. W. P. (2019) Low genetic connectivity in a fouling amphipod among man-made structures in the southern North Sea. Marine Ecology Progress Series, 615, 133 - 142. https: // doi. org / 10.3354 / meps 12929","Galil, B. S., Boero, F., Fraschetti, S., Piraino, S., Campbell, M. L., Hewitt, C. L., Carlton, J. T., Cook, E. J., Jelmert, A., Macpherson, E., Marchini, A., Occhipinti-Ambrogi, A., McKenzie, C. H., Minchin, D., Ojaveer, H., Olenin, S. & Ruiz, G. (2015) The enlargement of the Suez Canal and introduction of non-indigenous species to the Mediterranean Sea. Limnology and Oceanography Bulletin, 24 (2), 43 - 45. https: // doi. org / 10.1002 / lob. 10036"]}

Jassapusilla (Sars, 1894) (Table 11, Figs 37–41) Synonyms: see Conlan (1990). Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin without a fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with a few very short setae; carpus without a single or small cluster of setae at the anterodistal junction of the propodus. Gnathopod 2: basis with a few minute setae along the anterolateral margin but without long filter setae (most setal lengths Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process underlying about 1/4 of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae, only the usual short setae at each dorsolateral cusp. Thumbed male: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmar defining spines absent except in small males. Thumb distally acute or squared in minor males and indented in major males. Dactyl expansion variable, centrally toothed or shallowly expanded proximally. Adult female: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palm concave, palmar defining angle acute. Remarks. The shape of the male second gnathopod is highly variable but Fig. 39 shows how shapes can grade within a series, this being a single collection made by G. O. Sars from Ri&scirc;r, Norway. Juvenile males that approach the size of the thumbed males have pre-thumbs that are small relative to minor and major forms (Figs 39A, Band 40). The pre-thumb is located in the distal half of the palm. Those juveniles that are about to molt into a thumbed stage (showing a thumbed cuticle under the juvenile cuticle) are termed subadult in Fig. 40. These have small prethumbs as well. Minor forms are interpreted as being those that have thumbs that are also in the distal half of the palm (as in minor forms of other species) but that have a larger and longer thumb and never show a thumbed cuticle inside (i.e., will not molt again) (Figs 38 and 39 C–E). Minor forms also have centrally toothed dactyls (Figs 39 C–E). Major form males have longer thumbs that are apically indented at the tip. Their thumbs originate in the proximal half of the propodus (Figs 38 and 39 F–J). The dactyl expansion is shallow and proximal in most major forms (Fig. 39J) but is centrally toothed in some (Fig. 39G). Sars originally named the major form Podocerus pusillus and the minor form Podocerus odontonyx (Fig. 38) (see Conlan 1990). Fig. 39B is interpreted as being juvenile because no thumbed cuticle was visible internally, its pre-thumb is short relative to body length (Fig. 40) and its dactyl is not centrally toothed as in the minor forms (Figs 39 C–E). None of the specimens termed juvenile and subadult in Fig. 40 had centrally toothed dactyls. Four populations sampled in Väderârna, Sweden, Trondheimsfjord, Norway, Ri&scirc;r, Norway and Tórshavn, Farøe Islands showed a similar relationship between thumb length and body length, with the juveniles having prethumbs and the minor forms being rare (Fig. 40). Jassa pusilla is a small species, with the minor forms 2.8–3.8 mm in body length and the major forms 3.0– 4.5 mm in these four populations. The record of J. pusilla from samples along the coast of Portugal by Lobo et al. (2017) is in error, and is the new species J. laurieae. The three collections of J. pusilla from deep water offshore of the Atlantic U.S. coast (NMNH 6335, 33530, and 106781) (Fig. 9) morphologically resembled this species, not either of the other two species from this coast (J. valida and J. marmorata), which occur shallower. Jassa pusilla is a smaller species with delicate, never plumose antennae, lacking the typical long setae along the basis of gnathopod 2 that the other two possess, and also lacking the diagnostic antero-medial seta on the gnathopod 1 carpus at the junction of the propodus. The minor form thumbed male of Jassa pusilla has a strong tooth on the inner margin of the dactyl, which the minor forms of the other two species lack. One of the specimens from NMNH 6335 was a 3 mm long minor form thumbed male with a strong tooth on the dactyl, its propodus closely resembling that in Figs 38 and 39E. Another thumbed male (NMNH 33530) closely resembled Fig. 39B. The other specimens were female or juvenile. These three collections are the only ones known from the western North Atlantic., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 75-79, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Sars, G. O. (1894) Amphipoda. Part XXVII & XXVIII. Podoceridae (concluded), Corophiidae, Cheluridae. An account of the Crustacea of Norway, with short descriptions and figures of all the species, 1, 589 - 628. https: // doi. org / 10.5962 / bhl. title. 1164","Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288","Stebbing, T. R. R. (1906) Amphipoda. I. Gammaridea. Das Tierreich, 21, 1 - 806.","Lobo, J., Ferreira, M. S., Antunes, I. C., Teixeira, M. A. L., Borges, L. M. S., Sousa, R., Gomes, P. A., Costa, M. H., Cunha, M. R. & Costa, F. O. (2017) Contrasting morphological and DNA barcode-suggested species boundaries among shallow-water amphipod fauna from the southern European Atlantic coast. Genome, 60, 147 - 157. https: // doi. org / 10.1139 / gen- 2016 - 0009"]}

Jassajusti Conlan, 1990 (Table 13, Fig. 92) Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin without a fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with a fringe of short, spine-like setae; carpus without a single or cluster of setae at the anterodistal junction of the propodus. Gnathopod 2: basis with a row of short, spine-like setae along the anterolateral margin; carpus and propodus, setae on the anterior margin short and simple (setal lengths Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process underlying about 1/2 of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae (only the usual short setae at each dorsolateral cusp). Thumbed male: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmar defining spines produced on a ledge; dactyl expanded close to the junction with the propodus but not centrally toothed. Adult female: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palm concave, dactyl fitting into a depression between the palm and the defining spines. Remarks. Jassa justi shares with Jassa alonsoae, J. fenwicki, J. ingens and J. hartmannae the fringeof spine-like setae along the anterolateral margin of gnathopod 1. Gnathopod 2 sports a similar fringe. The proximal origin of the thumb in the holotype male suggests that it is a major form, in which case the pronounced palmar defining spines may be typical of all thumbed males, rather than being lost in larger major forms. This retention of the palmar defining spines by major form thumbed males would be similar to J. ingens (Fig. 99), while in most species the spines are lost. Jassa hartmannae and J. kjetilanna may also retain their spines as they are similarly produced but sample size is small. There were no minor form males of J. justi available for study. Like J. fenwicki and J. ingens, the propodus spines on pereopods 5–7 are pronounced, though the propodus is differently shaped and not expanded., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 143-144, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288"]}

Jassafalcata (Montagu, 1808) (Table 11, Figs 42–47) Synonyms: see Conlan (1990). Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin witha fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with a few very short setae; carpus without a single or small cluster of setae at the anterodistal junction of the propodus. Gnathopod 2: basis with a few minute setae along the anterolateral margin but without long filter setae (setal lengths Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process underlying about 1/2 of the longest ramus. Uropod 3: inner ramus with 1–2 spines mid-dorsally in addition to the usual single apical spine. Telson: tip without apical setae, only the usual short setae at each dorsolateral cusp. Thumbed male: Antenna 2: with plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmar defining spines absent except in small males. Thumb distally acute or squared in minor males and squared in major males. Dactyl centrally toothed in minor forms and shallowly expanded proximally in major forms. Adult female: Antenna 2: with plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palm concave, palmar defining angle bulbous, distal to and fairly distant from the defining spines. The basis of pereopod 3, which holds the tube spinning gland, was also measured as the width appeared to be greater in the females and juvenile males than in the adult males (Fig. 46b). Basis width was measured at the widest part of the basis which tended to be in the central part. The same individuals as for Gn2 propodus length were measured, with the addition of 6 additional adult males for which propodus length was lacking. Fig. 46b suggests that basis width was greater in the females and juvenile males (which included one subadult male) than in the adult males. Pairwise comparisons by Dunn’s Method showed a significant difference between major form adult males (n = 20) and juvenile males (n = 8) (Q = 2.905, pQ = 1.913 and 0.454, respectively), although Fig. 46b suggests a transitional difference. Because of the large variation in male thumb morphology in Jassa as well as the synonymy of previously recognized species to J. falcata by Sexton and Reid (1951), many references to J. falcata in the literature are mis-identifications. Conlan (1990) lists corrected identifications for those specimens that could be obtained. The specimens noted in Lobo et al. (2017) as being J. falcata are confirmed as this species (specimens examined 4 March 2019). So too are the specimens described by Walker (1911) (NHM). Remarks. Minor forms have a distinct tooth on the inner surface of the dactyl which inserts into the palmar incision on the propodus (Figs 42 and 45). In major forms, the thumb is long and the propodus deeply incised (Figs 43– 45). The dactyl lacks the obvious tooth of the minor form, though it is expanded proximally. These differences are so great that this lead Leach (1814) to describe the major form as J. pulchella; Montagu (1808) had based his description of J. falcata on a minor form male. Walker (1911) was of the opinion that both forms occurred within the species. Aplot of thumb length vs body length for a population sampled in summer at Audrassalas, France (Fig. 45) shows the shorter thumb length and dactyl toothing in the minor form and the very long thumb of the major form. Comparing mean thumb length between the minor form group (n = 2) and the major form group of the body length range (5.6–6.2 mm, n = 10) found that the differences were not great enough to exclude the possibility that the differences were due to random sampling variability (ANOVA, F = 4.289, p = 0.065). Minor forms were rare in this population and were uncommoninothercollectionsalso, despite 4,000 specimenshavingbeenexamined (Table 4). Aplot of gnathopod 2 propodus length for the same population (Fig. 46a) showed a significant difference between the major form adult male (n = 14), juvenile (including subadult) male (n = 8) and adult females (n = 5) within the body lengthrange whereeach overlapped (5.08–6.67 mm) (ANOVA, F = 22.112, p t -test, t = 5.631, p t = 5.107, p t = 1.175, p = 0.251)., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 81-87, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Montagu, G. (1808) Description of several marine animals found on the south coast of Devonshire. Transactions of the Linnean Society of London, 9, 81 - 114. https: // doi. org / 10.1111 / j. 1096 - 3642.1818. tb 00327. x","Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288","Leach, W. E. (1814) Crustaceology. The Edinburgh Encyclopedia, 7, 402 - 404.","Sexton, E. W. & Reid, D. M. (1951) The life-history of the multiform species Jassa falcata (Montagu) (Crustacea Amphipoda) with a review of the bibliography of the species. Journal of the Linnean Society of London, Zoology, 42, 283, 29 - 91. https: // doi. org / 10.1111 / j. 1096 - 3642.1951. tb 01852. x","Lobo, J., Ferreira, M. S., Antunes, I. C., Teixeira, M. A. L., Borges, L. M. S., Sousa, R., Gomes, P. A., Costa, M. H., Cunha, M. R. & Costa, F. O. (2017) Contrasting morphological and DNA barcode-suggested species boundaries among shallow-water amphipod fauna from the southern European Atlantic coast. Genome, 60, 147 - 157. https: // doi. org / 10.1139 / gen- 2016 - 0009","Walker, A. O. (1911) Notes on Jassa falcata (Mont.). Transactions of the Liverpool Biological Society, 25, 67 - 72."]}

Jassa spinipes (Johnston, 1829) Named Gammarus spinipes by Johnston (1829), this British species was “...found among Sertulariae taken from a fishing boat, so that it probably inhabits deep water.ʺNo further locality information was given. Johnston described the second gnathopod: “...the palm much dilated, armed with a single claw, and beneath with a conical spine, much like a claw. Between these there is a triangular process.” In his remarks, Johnston stated that “I cannot refer it to any described species. It surely cannot be the Jassa pulchella of Dr. Leach.” This is because, “...in Jassa pulchella the inferior antennae are the longest, and are said to be leg-shaped, a form which those of Gamm. spinipes have not, if Ihave a correct idea of what is meant by that term.” Johnston (1829) provided no illustrations for his new species description and the whereabouts of his type is unknown. This comparison of G. spinipes to J. pulchella is perhaps the reason why it appears in WoRMS as J. spinipes. In their comprehensive publications on the British Amphipoda, Bate (1862) and Bate & Westwood (1863, 1868) did not mention a species named spinipes, either of the genera Gammarus, Podocerus or Jassa. Stebbing (1906) mentioned G. spinipes in his addendum, only giving the reference for Johnston (1829). Lincoln (1979) did not mention either G. spinipes or J. spinipes in his updated treatment of the British Amphipoda. The reason for the transfer of G. spinipes to Jassa is not given in WoRMS and appears to be unjustified, given Johnston’s short description and lack of a type., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on page 161, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Johnston, G. (1829) Contributions to the British fauna. Zoological Journal, 4, 416 - 421.","Bate, C. S. (1862) Catalogue of the specimens of amphipodous Crustacea in the collection of the British Museum. Taylor & Francis, London, 399 pp.","Bate, C. S. & Westwood, J. O. (1863) A history of the British sessile-eyed Crustacea. Vol. I. John van Voorst, London, 507 pp. https: // doi. org / 10.5962 / bhl. title. 9917","Bate, C. S. & Westwood, J. O. (1868) A history of the British sessile-eyed Crustacea. Vol. II. John van Voorst, London. 536 pp.","Stebbing, T. R. R. (1906) Amphipoda. I. Gammaridea. Das Tierreich, 21, 1 - 806.","Lincoln, R. J. (1979) British marine Amphipoda: Gammaridea. British Museum (Natural History), London, 658 pp."]}

Genus Jassa Leach, 1814 Lusyta Nardo, 1847b, p. 20. Cratophium Dana, 1852b, p. 309. Macleayia Haswell, 1880, p. 32. Bruzeliella Norman, 1905, p. 83. Description of adult male. Body length at maturity 2–24 mm. Head lobe: oval or squared, but with dorsal angle more acute and ventral angle more broadly rounded. Antenna 1: accessory flagellum 2-articled, second minute, only second setose. Antenna 2: stouter and longer than antenna 1, bearing finely pectinate “filter setae” on peduncular articles 3–5 and shorter, pectinate “brush setae” on flagellum, in many species these being interspersed with feathery plumose setae on distal part of peduncular article 5 and proximal part of flagellum; flagellum with at least 2 of its distal articles bearing posteriorly curved spines, first article considerably longer than any of the distal articles. Mandible: at least 1 molar with 1 seta and 1 lateral flake. Maxilla 1: inner plate bearing a few short fine setae, palp with 1 or more rows of setae. Gnathopod 1: coxa rectangular, often anterodistally produced; propodus, palm defined by 3 spines that are usually arranged in medial-lateral-medial sequence. Gnathopod 2: coxa deeper posteriorly, with 1 gill; basis, setae, when present, simple or short and plumose, and located on the anterolateral flange only; carpus less than 0.25 of length of propodus; propodus with triangular, shallowly bifid tooth directly posterior to dactyl hinge and larger thumb incised anteriorly to palmar defining spines (or associated setae if spines absent), inner margin of thumb not setose, outer margin with 3-4 discrete clusters; dactyl shorter than propodus, extending beyond the thumb to rest against the thumb’s posterior margin when closed, inner margin expanded at location of hinge tooth or more centrally and acutely as a tooth into palmar incision, dactyl cusps reduced to small buttons interspersed with a few short setae. Pereopods 3 and 4: coxa 3 usually deepest posterior of centre; coxa 4 deepest centrally; basis, margins convex, or anterior margin straight or shallowly concave in large specimens; merus anterodistally produced to half to fully overlap the carpus, anterior margin bearing numerous setae in clusters or singly; propodus not posteriorly spinose. Pereopods 5–7: basis of at least one of peraeopods 5–7 posterodistally produced; merus and carpus, posterior margin not spinose; propodus variably expanded; dactyl, posterior (outer) margin not cusped distally, anterior (inner) margin bearing 1 seta at the unguis or short setae along its length. Pleopods: well developed, with 2 peduncular coupling hooks each in most species, but more in large species. Urosome: segment 1 bearing a pair of erect setae dorsally. Uropod 1: peduncle usually extended ventrally as a spinous process under the rami. Uropod 2: ventral spinous process short or absent. Uropod 3: peduncle finely setose ventrally, but without spines middorsally, and with a crown of spines around the dorsodistal margin and a cluster of setae distolaterally; outer ramus not setose mid-dorsally, tipped by a basally immersed, dorsally recurved spine, 2 large cusps, and many additional minute cusps; inner ramus tipped by 1 single short spine which is not recurved and not accompanied by cusps. Telson: each corner with 1 pair of button-like cusps accompanied by 1 long pectinate seta and 1 or 2 short plumose setae, but without spines. Description of adult female. Body length at maturity 2–21 mm. Character states as in the male except as follows. Brood plates: broad, setae abundant, tips hooked. Antenna 2: peduncle, posterior filter setae long. Gnathopod 2: propodus much larger and different in shape from the propodus of gnathopod 1, palm concave or sinuous, without a thumb, defining spines not lost with age; dactyl fitting into a depression between the palmar angle and spines. Peraeopod 3: basis broadly expanded, margins convex, not straight or concave. Variation. Antenna 2 may develop plumose setae on article 5 and the flagellum when individuals are approaching maturity, though small individuals that appear to be otherwise adult may not develop plumosity. This occurs in both sexes. The mandibular palp article 2 may bear a row of setae on the dorsal margin in a few species. The maxilla 1 may bear a cluster of setae at its base though most species lack these setae. Akey character is the presence or absence and length of a single or cluster of setae on the anterodistal margin of the carpus at the junction of the propodus in gnathopod 1. If present, these setae may be slightly medial or lateral. The bases of gnathopods 1 and 2 may or may not possess a row of setae and the presence and length of these setae is a key character for species definition. The propodus of gnathopod 2 may have a concave or sinuous palm in the juveniles and adult females. Large subadult males may have a small thumb, termed a “pre-thumb” at the location where the much larger thumb will appear at the last molt. Small subadults of the same species do not exhibit a pre-thumb. At the terminal molt, the thumb may be long or short, sinuous or straight, incised, acute or squared at the tip. “Major form males” have larger thumbs than “minor forms”, but being at the terminal molt, a minor form does not transition into a major form. The minor form may have a tooth on the dactyl that fits into the palmar incision. In the major form, the dactyl is expanded on its inner margin close to the hinge. Most terminal molt species lose their palmar defining spines that are present in the juvenile; the female always retains these spines. For all species the number of spines defining the gnathopod palms may be occasionally 2 or 4 rather than the usual 3. The bases of pereopods 3 and 4 are wide with convex margins in juveniles and females but the bases are slenderer in the thumbed male. In a few species the propodus of pereopods 5–7 may be prehensile. The peduncular spinous process of uropod 1 is absent in some species. The number of major cusps adjacent to the recurved spine that tips the third uropod outer ramus may be rarely 3 or 4 rather than 2. The inner ramus bears extra spines mid-dorsally in some species. Unless noted otherwise, these interspecific differences apply to both sexes and all ages of a species. Species treatments. The key characters of the 24 species are presented following, with the species grouped by commonality of distribution: trans-hemispheric (Table 10 and Figs 15–36), North Atlantic (Table 11 and Figs 37–59), North Pacific (Table 12 and Figs 60–87) and Southern Hemisphere (Table 13 and Figs 88–104). Key characters are not affected by age or gender and so can be used for the identification of most specimens, with the possible exceptionofhatchlings. Someadditionalgenderandage-specificcharactersareaddedtoassistwithidentification. Followingthespeciestreatmentsisakeytoall 24 species. Whilethedistributionalformatisaimedtosimplify regional identifications, the key should be checked in case the specimen is a new species or a new introduction., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 43-44, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Leach, W. E. (1814) Crustaceology. The Edinburgh Encyclopedia, 7, 402 - 404.","Nardo, G. D. (1847 b) Sinonimia moderna delle specie registrate nell' opera intitolata: descrizione de' crostacei, de' testacei e de' pesci che abitano le lagune e golfo Veneto rappresentanti in figure, a chiaro-scuro ed a colori dall' Abate Stefano Chiereghini: Venezia, Ven. Clodiense, applicata per commissione governativa dal Dr. Gio. Domenico Nardo. G. Antonelli, Venezia, 127 pp. https: // doi. org / 10.5962 / bhl. title. 120206","Dana, J. D. (1852 b) On the classification of the Crustacea Choristopoda or Tetradecapoda. American Journal of Sciences and Arts, Series 2, 14, 297 - 316.","Haswell, W. A., 1880. Preliminary report on the Australian Amphipoda. Annals and Magazine of Natural History, Series 5, 5, 30 - 34. https: // doi. org / 10.1080 / 00222938009459377","Norman, A. M. (1905) VIII. - Revised nomenclature of the species described in Bate and Westwood's ' British Sessile-eyed Crustacea'. Journal of Natural History, 16 (91), 78 - 95. https: // doi. org / 10.1080 / 03745480509443653"]}

Jassamyersi Conlan, 1990 (Table 12, Figs 85–87) Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin without a fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with a few short setae along its length; carpus with a single or small cluster of relatively long setae at the anterodistal junction of the propodus (setal length about 1/3 the length of the anterior margin length). Gnathopod 2: basis with only a few short setae along the anterolateral margin (setal lengths Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process very short, underlying about 6% of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae (only the usual short setae at each dorsolateral cusp). Thumbed male: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmar defining spines not produced on a ledge. Adult female: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palm sinuous, palmar defining angle shallowly rounded and towards the centre of the palm (not close to the palmar defining spines). Remarks. This is the only Northern Hemisphere species that has a sinuous palm on the propodus of gnathopod 2. It also has a variably fringed basis, leading to mixed interpretation of whether a fringe of setae is present or absent. It shares with J. borowskyae and J. shawi a reduced peduncular process underlying the rami of uropod 1. Among the 166 specimens available for study, there were only 8 thumbed males. These all had very short thumbs and palmar defining spines proximal to the base of the thumb. The thumbed males had shorter setae on the antenna 2 than the females (Fig. 85) but none had plumose setae as develops in thumbed males of some other species of Jassa. This may signify that J. myersi does not develop plumose setae but the sample size is small. However, none had slenderized bases of pereopods 3–4 which is typical of large thumbed males. Conlan (1990) suggested, therefore, that these males were not at maximal size for the species. Aplot of gnathopod 2 propodus length relative to body length shows an apparent greater size for males than females (Fig. 87). Analysis of variance on adult females (n = 4) and juvenile males (n = 6) that overlapped in body length (3.5–4.5 mm) found that the differences in mean propodus length was not sufficiently great to exclude the possibility that the difference was due to random sampling variability (F = 1.041 -15, p = 1.0). Southern Hemispherespecies, Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 133-137, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288"]}

Jassaingens Pfeffer, 1888 (Table 13, Figs 99–101) Synonyms: see Conlan (1990). Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin without a fringe of setae. Maxilla 1: with a small cluster of setae at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with a few to a full row of short setae along its length which may be slender or spine-like; carpus with a single or small cluster of setae at the anterodistal junction of the propodus (setae about 1/3 of anterior margin length and slightly lateral and medial). Gnathopod 2: basis with a row of small setae along the anterolateral margin (setal lengths Pereopods 5–7: propodus expanded anteriorly. Uropod 1: ventral peduncular spinous process underlying about 40% of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae (only the usual short setae at each dorsolateral cusp). Thumbed male: Antenna 2: large individuals without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmar defining spines produced on a ledge, present in both small and large thumbed males. Adult female: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmsinuous. Remarks. All of the thumbed males available for study had relatively short thumbs with the palmar defining spines present and produced on a ledge, suggesting that these spines are not lost even in the largest animals. The antenna 2 setae are long in small juveniles but shorten drastically in the adult males. The expanded propodus of pereopods 5–7 is distinctive, even in the young. This is the largest species known for the genus, with body length at maturity in the specimens available 19.6–24.1 mm for the adult (thumbed) males and 15.3–20.8 mm for the adult females., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 152-153, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Pfeffer, G. (1888) Die krebse von Sud-Georgien nach der ausbeute der Deutschen station 1882 - 83. 2. Die Amphipoden. Hamburg Wissenschafftlichen Anstalten Jahrbuch, 5, 75 - 142. https: // doi. org / 10.5962 / bhl. title. 10084","Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288"]}

Jassalaurieae n. sp. ( Table 11, Figs 54, 55) Diagnosis. Male: Mandibular palp: article 2, dorsal margin without a fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with a few minute setae along its length; carpus without a single or cluster of short setae at the anterodistal junction of the propodus. Gnathopod 2: basis without a row of long setae along the anterolateral margin (setae minute, << basis width); carpus and propodus, setae on the anterior margin minute (setal length << basis width). Pereopods 5–7: missing. Uropods: missing. Telson: missing. Thumbed male: Antenna 2: large individuals with plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmar defining spines not produced on a ledge, absent in large thumbed males (state for small thumbed males unknown). Minor males unknown. Major males, thumb distally rounded and on the proximal half of the propodus. Dactyl expanded close to the junction with the propodus but not centrally toothed. Adult female: Unknown. Description. Male, holotype. Length ~ 4.7 mm. Antenna 1: each article with long filter setae on the posterior margin; accessory flagellum 2 articles, the second minute; flagellum 4 articles, each bearing aesthetascs. Antenna 2: stouter than antenna 1 and overlapped by antenna 1 to 2/3 the length of article 5; distal part of article 4 and full length of article 5 and flagellum bearing plumose setae on the posterior margin in addition to filter setae which are about the same length; flagellum 4 articles, article 1, 50% of flagellum length, article 4, 40% as long as article 3, flagellum articles 2–4 bearing curved spines posterodistally. Mandible: palp articles 2 and 3 without dorsal fringe of setae; raker spines 1 right, 4 left. Maxilla 1: inner plate bearing a few short, fine setae; palp without setae at the base of article 1; article 2 with 1 row of facial setae. Gnathopod 1: coxa produced forward, coxal margins, anterior 175% of dorsal length, ventral margin straight; basis flanged anteriorly, anterior margin without a fringe of long setae (all setae minute), posterior margin without setae; carpus, posterior lobe 45% of anterior margin length, without an anterodistal setal cluster; propodus, palm convex, defined by 3 spines (medial-lateral-medial), these mid-distant along the palm; dactyl facially striated. Gnathopod 2: coxa rounded, coxal margins, anterior 26% and posterior 38% of ventral length, ventral margin convex; gill present; carpus, posterior lobe with a cluster of setae; propodus, anterior margin with only a few minute setae proximally (setae << the width of the basis), palm with a few plumose setae at the dactyl hinge, defined by a long, straight thumb that is rounded at the tip, without palmar defining spines, thumb length 35% of propodus length. Pereopod 3: coxa deepest posteriorly; basis, margins convex; merus, setae 1/2 article width, article width maximally 65% of length; carpus nearly 100% overlapped by the merus; propodus not posteriorly spinose. Pereopod 4: coxa nearly rectangular, deeper than wide, ventrally convex; other articles as for pereopod 3. Pereopods 5–6: missing. Pereopod 7: coxa-ischium missing, distal articles slender, propodus not distally expanded, with small spines only anterodistally at the junction of the dactyl; dactyl, posterior (outer) margin not cusped distally, anterior (inner) margin bearing a seta only at the unguis. Pleopods: missing. Uropods: missing. Telson: missing. Condition. Mouthparts, right antennae 1 and 2, gnathopod 1, left gnathopod 2, and right pereopods 3 and 4 slide mounted. Whole body with left antenna 2 and gnathopod 1, right gnathopod 2 (coxa to merus) and left pereopod 4 in 70% ethanol. Missing posterior portion of the body from pereon segment 4 onwards, which had been removed for CO1 analysis. Variation. Maximum body length: male ~ 4.8 mm. Type material examined. Holotype, male, ~ 4.7 mm, from macroalgae at Praia Norte, Viana do Castelo, Portugal (41.6938, -8.85118), Pedro Gomes, collector, 23 September 2010, Specimen ID SFC 29-003, Process ID FCCOM341- 11. Donated by Filipe Costa, University of Minho, Portugal, to the Canadian Museum of Nature (CMN A2019.0061, catalogue no. CMNC 2019-1385). Paratype, male, ~ 4.8 mm, same location, date and collector, Specimen ID SFC 29- 002, Process ID FCCOM340-11 (catalogue no. CMNC 2019-1386). Etymology. Named in honour of artist Susan Laurie-Bourque who skillfully illustrated all the plates for this paper, Conlan (1990; in press), and many earlier taxonomic treatments. Remarks. Jassa laurieae is only known from the holotype and paratype specimens which are both major form adult males. Both specimens had the posterior portions of their body removed for CO1 analysis, with the results published in Lobo et al. (2017). Body length has been estimated based on the expected length of the remaining body using J. kimi as a model, which is similarly sized. The actual body portion available for study was 1.8 mm long for the holotype and 1.2 mm long for the paratype. Lobo et al. (2017) considered J. laurieae to be a Portuguese variant of J. pusilla, but the CO1 analyses revealed that both the holotype and paratype were genetically similar and clearly distinct from North Sea specimens of J. pusilla as well as from Portuguese and North Sea J. falcata, J. herdmani and J. marmorata, and from U.S. J. staudei. Jassa laurieae is only known from the Atlantic coast of Portugal, where it may be found with J. falcata, J. pusilla and J. herdmani (Fig. 9). Morphologically, the major form males of J. laurieae and J. falcata are similar in appearance at the anterior end, with plumose setae on antenna 2, minute setae on the anterior bases of gnathopods 1 and 2, absence of a seta or cluster of setae on the anterodistal margin of the gnathopod 1 carpus at the junction of the propodus, and relatively long thumb with rounded tip. The two differ in that J. laurieae lacks the dorsal fringe of setae on article 2 of the mandibular palp which both J. falcata and J. herdmani consistently possess in both sexes and all ages. Jassa falcata is also distinctive in having 1–2 spines midway along the inner ramus of uropod 3, but the state for J. laurieae is unknown. Large major form J. falcata have a very long thumb which is more squared at the tip than in J. laurieae but there are too few specimens of the latter to determine variation. Jassa laurieae is less similar in appearance to congener J. pusilla than to J. falcata in the major form male, although the females and juveniles may prove to be more similar. Major form males of J. pusilla develop an indent at the tip of the thumb and never have plumose setae on the antenna 2. Both species are similar in lacking the dorsal setal cluster on article 2 of the mandibular palp and lack of a seta or setal cluster on the anterodistal junction of the carpus with the propodus on gnathopod 1. They are also similar in their small body length, while J. falcata achieves a greater length. Until more specimens of J. laurieae are found, these two species are currently only distinguishable by the major form male. Additional distinguishing characters may occur on the posterior region of the body, though. Jassa herdmani bears the distinguishing setal fringe on article 2 of the mandibular palp (any age, both sexes), and this serves to easily separate it from J. laurieae. Major form males of J. herdmani do not bear plumose setae on antenna 2 and achieve greater body size., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 94-97, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288","Lobo, J., Ferreira, M. S., Antunes, I. C., Teixeira, M. A. L., Borges, L. M. S., Sousa, R., Gomes, P. A., Costa, M. H., Cunha, M. R. & Costa, F. O. (2017) Contrasting morphological and DNA barcode-suggested species boundaries among shallow-water amphipod fauna from the southern European Atlantic coast. Genome, 60, 147 - 157. https: // doi. org / 10.1139 / gen- 2016 - 0009"]}

Jassacarltoni Conlan, 1990 (Table 12, Figs 78–82) Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin without a fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with a few short setae along its length; carpus with a (usually) single or a small cluster of long setae at the anterodistal junction of the propodus (setae 65-70% of anterior margin length andslightly medial). Gnathopod 2: basis with a few moderately long setae on the anterodistal margin (most setal lengths Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process underlying about 1/3 of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae (only the usual short setae at each dorsolateral cusp). Thumbed male: Antenna 2: without plumose setae on peduncular article 5 and flagellum. Gnathopod 2: propodus large and stout, palmar defining spines not produced on a ledge, spines lost in large thumbed males. Major form: thumb about 30% the length of the propodus and curved posterodistally, dactyl sinuous, expanded proximally. Minor form: thumb about 15% the length of the propodus, dactyl expanded more distally than in the major form, into the palmar incision between the thumb and the proximal tooth. Adult female: Antenna 2: without plumose setae on peduncular article 5 and flagellum. Gnathopod 2: propodus, palm concave, palmar defining angle acute, palmar defining spines relatively widely spaced. Remarks. Conlan (1990) first recognized Jassa carltoni as a new species in Californian collections described by Barnard (1969) as “ Jassa falcata ”. The largest specimens available were chosen as the type lot (Fig. 78). However, the holotype, a major form male, appears to have a damaged thumb, as the tip is short and apically indented compared to the major form paratype (Fig. 79). The minor form paratype (Fig. 79) has a similarly shaped but shorter thumb with the dactyl expanded into the palmar incision. Additional specimens from British Columbia are figured in order to show the morphology of an undamaged major form male as well as a subadult male that had an obvious thumb inside the cuticle. Plots of thumb and propodus length on gnathopod 2 for specimens from a single population show that the major form thumbed male has a substantially longer thumb and gnathopod 2 propodus length than the minor form thumbed male (Figs 79, 80). Propodus length of adult females is also much less than for major form males but more similar to minor form and subadult males. However there were insufficient specimens of similar body length for statistical comparison. Jassa carltoni most resembles J. slatteryi, both of which occur on the Pacific coast of North America. Although both have a 4-articled flagellum on antenna 2, the flagellum is slenderer in Jassa carltoni than in J. slatteryi and unlike J. slatteryi, it does not become plumose in large thumbed males. The palm of gnathopod 1 is convex while in J. slatteryi it is straight or shallowly concave. Both males and females of J. carltoni have a sparser setation on the anterior margin of the basis and a wider propodus on gnathopod 2 (maximal width ~65% of maximal length) than for J. slatteryi (maximal width ~50% of maximal length). The thumb shape also differs: tip rounded and curved posteriorly in major form males of J. carltoni and tip acute and not curved posteriorly in major form males of J. slatteryi. In minor form males of J. carltoni, the thumb is shorter and more acute than in the major forms, and more closely resembles J. slatteryi. The shape differences in the gnathopod 1 palm still hold, though. Many (but not all) of the locations for J. slatteryi noted by Conlan (1990) for British Columbia are actually for J. carltoni, as this latter species was not recognized at that time to occur outside of California. It was only through recent molecular analysis that J. carltoni was discovered to occur also in British Columbia. Subsequent re-examination of collections found J. carltoni also in Oregon. A “ J. slatteryi ” noted by Conlan (1990) from Alaska (University of Alaska loan, Latouche T1, M75, 5 Sept. 1975) may also be J. carltoni but this specimen was no longer available for study and so is omitted from the distribution map. Given the similarity in environmental conditions between southeastern Alaska and British Columbia, it is likely that J. carltoni ranges northwards at least into southeastern Alaska. Jassa carltoni has not been found outside of the Pacific coast of North America, however., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on page 126, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288","Barnard, J. L. (1969) Gammaridean amphipoda of the rocky intertidal of California: Monterey Bay to La Jolla. Bulletin of the United States National Museum, 258, 1 - 230. https: // doi. org / 10.5479 / si. 03629236.258.1"]}

Jassaborowskyae Conlan, 1990 (Table 12, Figs 65–66) Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin without a fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin without a row of short setae along its length; carpus with a single or small cluster of long setae at the anterodistal junction of the propodus (setae 95% of anterior margin length and slightly lateral). Gnathopod 2: basis with a row of setae along the anterolateral margin (setae>50% of basis width); carpus and propodus, setae on the anterior margin short and simple (setal length Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process very short, underlying only 10% of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae (only the usual short setae at each dorsolateral cusp). Thumbed male: Antenna 2: large individuals with plumose setae on the flagellum and peduncular article 5 and lacking long filter setae. Gnathopod 2: propodus, palmar defining spines not produced on a ledge, present in small thumbed males but absent in large thumbed males. In minor males, the thumb is distally acute, short relative to body length and located on the distal half of the propodus. The dactyl is not strongly centrally toothed. In major males, the thumb is distally squared, longer relative to body length and on the proximal half of the propodus. The dactyl is expanded close to the junction with the propodus but is not centrally toothed. Adult female: Antenna 2: large animals with plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palm concave, palmar defining angle acute. Remarks. Jassa borowskyae shares the abbreviated process on uropod 1 with two other Northeastern Pacific species, J. myersi and J. shawi while all other species of Jassa have a well developed peduncular process that is 25% to 50% the length of the longest ramus. However, these latter two species lack the diagnostic dense setal fringe on the basis of gnathopod 2 that J. borowskyae possesses. Many more minor than major form adult males were found in the collections of J. borowskyae available for study but there were not enough specimens from a single population to plot the relationship of thumb length or propodus length to body length., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 112-114, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288"]}

Jassathurstoni Conlan, 1990 (Table 13, Figs 93–94) Diagnosis. Both sexes: Mandibular palp: article 2, dorsal margin without a fringe of setae. Maxilla 1: without a seta or setal cluster at the base of the palp article 1. Gnathopod 1: basis, anterolateral margin with only a single short seta distally; carpus with a small cluster of moderately long setae at the anterodistal junction of the propodus (setae 25% of anterior margin length). Gnathopod 2: basis with only a few minute setae along the anterolateral margin (setal lengths Pereopods 5–7: propodus not expanded anteriorly. Uropod 1: ventral peduncular spinous process underlying about 1/2 of the longest ramus. Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine). Telson: tip without apical setae (only the usual short setae at each dorsolateral cusp). Thumbed male: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palmar defining spines not produced on a ledge; dactyl expanded close to the junction with the propodus but not centrally toothed. Adult female: Antenna 2: without plumose setae on the flagellum and peduncular article 5. Gnathopod 2: propodus, palm sinuous; dactyl, inner margin evenly curved, tip fitting into depression between palmar angle and defining spines. Remarks. Only two thumbed males of J. thurstoni were available for study, both of which were major forms. Therefore, the appearance of the minor form is unknown. Jassa thurstoni is morphologically similar to J. kjetilanna and both have been collected in the Falkland Islands. Acomparison of the two species is given in the Remarks for J. kjetilanna. Compared to the Southern Hemisphere J. fenwicki and J. ingens, Jassa thurstoni has a slender antenna 2 without brush or plumose setae on the flagellum and the pereopods 5–7 are not modified for grasping. It also lacks the fringe of spine-like setae along the anterolateral margin of gnathopod 1, which is typical of the Southern Hemisphere species J. alonsoae, J. fenwicki, J. hartmannae, J. ingens and J. justi.Another Southern Hemisphere species that lacks the fringe, J. gruneri, differs from J. thurstoni in lacking a seta or cluster of setae at the anterodistal junction of the gnathopod 1 carpus with the propodus, while J. thurstoni possesses a setal cluster there. Jassa gruneri also possesses a short fringe of relatively long setae on the basis of gnathopod 2 while J. thurstoni lacks this fringe. Jassa thurstoni is only known from the Antarctic and sub-Antarctic islands while J. gruneri is only known from Tasmania (Figs 11–12)., Published as part of Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, pp. 1-191 in Zootaxa 4939 (1) on pages 145-147, DOI: 10.11646/zootaxa.4939.1.1, http://zenodo.org/record/4580622, {"references":["Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288"]}

Pleojassa orientalis n. sp. (Fig. 28) Description of adult female. Holotype: Length 9.8 mm. Antenna 2: overlapped by antenna 1 to the end of article 5; article 5, posterior margin bearing long simple setae only, without plumose setae; flagellum 3 articles, article 1 89% of the full flagellum length. Mandible: palp articles 2 and 3 without a dorsal fringe of setae; raker spines, number not measured. Gnathopod 1: coxal margins, anterior 140% of dorsal length; ventral margin shallowly convex; basis, anterior margin with a few short setae distally, posterior margin not setose; carpus, length 75% of propodus length, posterior lobe 59% of anterior margin length, without an anterodistal setal cluster; propodus, palm convex, with two defining spines slightly proximal of centre. Gnathopod 2: coxal margins, anterior 44% and posterior 73% of ventral length; ventral margin shallowly concave; carpus less than 1/4 the length of propodus; propodus, hinge tooth large and conical, not anteriorly bifid, palmar setae plumose, distributed throughout the palm, but not so dense as to obscure the palm’s shape, palmar angle acute, with a single, minute spine at its corner; dactyl, inner margin slightly sinuous. Pereopod 3: coxa, greatest depth posterior of centre; basis, anterior margin shallowly convex; merus, anterior marginal setae in well separated clusters, central setae, length 1/2 or less the article width, article width 72% of length; carpus 42% overlapped by merus; propodus, width 48% of length. Pereopods 5–7: setae and spines moderately abundant, basis posterodistally produced, anterior margin spinose; merus, posterior margin not spinose. Uropod 1: peduncle, posteroventral spinous process underlying 52% of the inner ramus, inner and outer rami with 10 and 6 mid-dorsal spines respectively. Uropod 2: peduncle, posteroventral spinous process underlying 42% of the inner ramus. Uropod 3: inner ramus with 2 spines mid-dorsally. Condition. Without left pereopod 5 and right pereopod 6. Flagellum of right antenna 1 lacking terminal article(s). Right appendages, left pereopod 6, and telson slide mounted. Description of male. Allotype: Length approximately 6.5 mm; head to end of segment 6, 3.9 mm. Character states as in the female except as follows. Antenna 2: article 5, filter setae half or less the length of those in the female, interspersed with plumose setae. Gnathopod 2: as in the female, but palm less densely setose and dactyl inner margin straight. Condition. Without body segments posterior of segment 6, antennae 1 flagella, left antenna 2 distal flagellum, right antenna 2, left pereopods 5–7, and right pereopods 5 and 7. Variation. Maximum body length: male unknown, female 9.8 mm. The male is 2/3 the body length of the adult female holotype (judging by relative difference in head length). This suggests that this male may not yet be mature, so it cannot be assumed that larger males lack a thumb as illustrated for the smaller male. Due to lack of material, sexual variation and growth is not well known and only can be inferred from congeners. Judging by its close resemblance to P. multidentata, in which the male is known to grow a thumb, this development is probably similar in P. orientalis. The small male bears plumose setae on the antenna 2 while the adult female lacks plumose setae. However, as in P. wandeli, larger females may have plumose setae. Type material examined. Holotype, &female;, ovigerous (AM), type no. P.34955, station no. MA-147, Macquarie Island: Gorilla Head Rock, southeast corner (54 o 29ʹS, 158 o 58ʹE), 23 December 1977, in a small Durvillea antarctica holdfast, 8 m. Allotype, small (juvenile?) &male; (AM), type no. P.37924, same location. Paratype, juvenile &female; (AM), type no. P.37925, same location. Etymology. In reference to the eastern location of the species relative to P. multidentata. Remarks. Pleojassa orientalis differs from P. multidentata in the shape of the gnathopod 2 palm (both sexes) (Figs 27 and 28), and in lacking a cluster of short setae at the anterodistal margin of the carpus of gnathopod 1, which is present in P. multidentata. Pleojassa orientalis may prove to be a geographic variant of P. multidentata, given the wide longitudinal range that Southern Hemisphere species can have (Figs 1 and 2). They are given separate species status herein because these morphological differences are key characters for distinguishing species in Jassa (Conlan et al., in press) and this may be the same case in Pleojassa and other relatives of Jassa., Published as part of Conlan, Kathleen E., 2021, New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini, pp. 1-72 in Zootaxa 4921 (1) on pages 48-49, DOI: 10.11646/zootaxa.4921.1.1, http://zenodo.org/record/4496015

Ventojassa frequens (Chilton, 1883) (Figs 8–16) Podocerus frequens Chilton, 1883, 85, Plate III, Fig. 2; Thomson & Chilton, 1886, 143; Shaw & Poore, 2016, 37–38 Podocerus latipes Chilton, 1884, 258, Plate XIX, Fig. 2; Thomson & Chilton, 1886, 143; Shaw & Poore, 2016, 38 Jassa frequens (Chilton), Stebbing, 1906, 656; Chilton, 1921, 227, Fig. 4; Schellenberg, 1931, 253; 1953, 119–120, Fig. 6; J. L. Barnard, 1958, 85 Jassa pusilla: K. H. Barnard, 1932, 242–243 Jassa barnardi Stephensen, 1949, 50–52, Figs 21, 22; J. L. Barnard, 1958, 84 Ventojassa frequens (Chilton), J. L. Barnard, 1972, 135–137, Figs 74–75; Griffiths, 1975, 138, 140; Gonzalez, 1991, 58 Description of male. Type: based on CMNZ 2015.149.86 (Fig. 8). (Character states for the two males in Figs 10 and 11 added in brackets and italics if the appendage is obscured in the type). Length 4.0 (3.6, 3.3) mm. Antenna 1: accessory flagellum 2 articles (right), 3 articles (left). Antenna 2: similar in length and width to antenna 1, with filter setae in the male as long as in the juvenile and female; flagellum 7 articles, the last as long as the second last, article 1 25% of full length, articles 5–7 posterodistally spinose. Mouthparts obscured (Mandible: articles 2 and 3 with a dorsal fringe of setae; raker spines, 4 right, 2 left. Maxilla 1: inner plate bearing a few short, fine setae; palp without setae at the base of article 1, article 2 with 1 row of facial setae distally). Gnathopod 1: coxae to propodus obscured (coxa rectangular, coxal margins, anterior 70% of dorsal length, ventral margin gradually rounded; basis, anterior margin without a fringe of setae laterally, with only a few setae at the anterodistal junction with the ischium, with 1 long seta on the posterior margin; carpus, length 90% of propodus length, posterior lobe 60% of anterior margin length, anterodistal setal cluster short, 5% of the anterior margin length; propodus, palm convex, defined by 1 spine); dactyl cusped distally, without facial striations. Gnathopod 2: (with a gill); coxae to antero-proximal part of propodus obscured (coxa not deeper posteriorly, coxal margins, anterior 100% and posterior 100% of ventral length, ventral margin gradually rounded; basis, anterolateral flange without a row of long, simple filter setae; carpus, anterior margin 50% the length of the propodus anterior margin, posterior lobe with a cluster of short distal setae; propodus, anterior margin with only a few distal clusters of short setae (setae about 20% of basis width)); propodus without hinge teeth, palm sparsely setose throughout, without a palmar defining spine, thumb conical in shape, 20% the length of the propodus and carpus combined; dactyl shorter than propodus, not expanded near the hinge, tip apposing the thumb tip, inner margin cusped. Pereopod 3: coxa and basis obscured (coxa deepest centrally; basis wider than the gnathopod 1 basis, anterior margin shallowly convex); merus, anterior margin with one seta midway and cluster of setae distally, article width 70% of length; carpus barely 20% overlapped by merus; propodus width 47% of length, not posteriorly spinose. Pereopods 5–7: proximally obscured (robust, basis, merus, carpus and propodus all bearing spines singly or in clusters; at least one basis posterodistally produced); propodus not strongly expanded anteriorly; dactyl not facially serrated, posterior (outer) margin not cusped distally, anterior (inner) margin setose only at the junction of the unguis. Pleopods: each with 2 coupling hooks (rami short, ≤ depth of the pleon). Urosome: segment 1 with pair of dorsally erect setae. Uropod 1: obscured (posteroventral spinous process underlying 83% of the inner ramus, inner and outer rami with 2 mid-dorsal spines, outer ramus with 3 mid-dorsal spines, inner ramus with 1, in addition to the distal spine group). Uropod 2: obscured (peduncle, posteroventral spinous process underlying 25% of the inner ramus). Uropod 3: partially obscured (peduncle not mid-ventrally setose, without mid-dorsal spines, without spines at the insertion of the rami, but with a cluster of setae distolaterally); outer ramus with 2 erect setae mid-dorsally (and tipped by 2 small, straight spines distolaterally and adjacent small cusp; inner ramus not mid-dorsally spinose or setose, with a single apical spine). Telson: partially obscured, with a pair of strong cusps dorsolaterally (and a single cusp at each dorsal apex, accompanied by a strong, erect seta and pair of small plumose setae). Condition. Whole body slide mounted; missing one pereopod 7. Description of adult female. Type: based on CMNZ 2015.149.85 (Fig. 9). Descriptions of characters not visible in the type are in brackets and italics and based on the adult female in Fig. 10. Length 3.8 (4.0) mm. Character states as in the male except as follows. Brood plates: obscured (relatively slender, setae well separated, abundant, hook-tipped). Antennae 1 and 2: similar in length, article 5 without plumose setae, simple filter setae as long as those of the male. Gnathopod 2: propodus without a hinge tooth, palm 40% of the posterior margin, setae not so dense as to obscure the palm’s shape, defined by 3 medial spines. Condition. Whole body slide mounted. Without right antenna 2 and pereopods 5–7, left pereopods 5 and 7. Variation. Maximum body length: male 4.5 mm, female 4.5 mm. There is some variation in the number of accessory flagellum articles on antenna 1. There can be 2 or 3 articles and this can also vary between right and left sides of an animal (Fig. 13). The females and small males can have 3 palmar defining spines on the propodus of gnathopod 2 rather than 2. The number of erect setae on the outer ramus of uropod 3 varies from 1 to 5. Type material examined. Type, conical thumbed &male;, CMNZ 2015.149.86, Lyttelton Harbour, New Zealand, date unknown, Charles Chilton, coll. Type, adult &female;&female;, CMNZ 2015.149.85 and 84, Lyttelton Harbour, New Zealand, date unknown, Charles Chilton, coll. Other material examined. New Zealand: Lyttelton Harbour, date unknown but possibly 1883 or earlier, C. Chilton, coll., 3 conical thumbed &male;&male;, 2 cubic thumbed &male;&male;, 18 adult &female;&female;, 5 juveniles (CMNZ 2015.149.575...604); Lyttelton, 28 Mar. 1928, 1 conical thumbed &male;, 5 adult &female;&female; (SNM); Brighton, Otago, New Zealand, Jan. 1890, C. Chilton, coll., 1 cubic thumbed &male; (CMNZ 2015.149.2161); Stewart I., date unknown, H. B. Kirk, coll., 1 adult &female; (CMNZ 2015.149.2116); Huaroa Point, Whangaparaoa Peninsula, Auckland Province, New Zealand (36.595°S, 174.836°E), 16 Feb. 1968, J. L. Barnard, coll., NIWA station E979, JLB NZ-14, low water level, on heavy stand of algae, including Cystophora torulosa and bases of dying Codium sp., 1 cubic thumbed &male; (NIWA 7825), 1 adult &female; (NIWA 7835), 1 cubic thumbed &male; (NIWA 7839); St. Kilda Rocks, Kaikoura (42.42°S, 173.7°E), 8 Nov. 1973, G. D. Fenwick, coll., 3–4 m depth on Caulerpa brownii and green algae, 8 cubic thumbed &male;&male; (AM P.25948) and ~ 50 specimens (MNZTPT CR.007823); Fraser Rocks, Tapeka, Bay of Islands, Northland, 15 Nov. 1995, 0–1 m, collector unknown, 31 conical thumbed &male;&male;, 43 adult &female;&female;, 23 juveniles (AuM MA 134534). Tristan da Cunha: type series for Jassa barnardi Stephensen, 1949: Norwegian Scientific Expedition, E. Sivertsen, coll., Nightingale station 113, 8 Feb. 1938, 19 conical thumbed &male;&male;, 37 adult &female;&female;, 56 juveniles (SNM), Nightingale station 114, 8 Feb. 1938, 0 m, 6 conical thumbed &male;&male;, 21 adult &female;&female;, 7 juveniles (UiO F3934) and 1 conical thumbed &male;, 1 adult &female; (CMNC 1994–0444), Inaccessible station 154, 25 Feb. 1938, 40 m, 1 conical thumbed &male;, 1 adult &female;, 10 juveniles (UiO F3898), Inaccessible station 156, 29 Feb. 1938, 5– 8 m, 3 adult &female;&female; (UiO F3897), station unknown, 30 Dec. 1939, 1 juvenile (SNM). Chile: Caleta Bruna, date unknown, collector unknown., 1 conical thumbed &male;, 1 adult &female;, 1 juvenile (MNHN Am. 2649); Valparaiso, collector and date unknown, 1 conical thumbed &male;, 8 adult &female;&female;, 2 juveniles (NRM 3786). South Africa: False Bay, date unknown, C. Griffiths, coll., station FAL 604G, 1 cubic thumbed &male;, 1 juvenile &male; (UCT). Remarks. Ventojassa frequens does not exhibit sexual dimorphism in the antenna 2 but does in the gnathopod 2 and enlargement of pereopods 5 and 6 relative to 7. The pereopod enlargement is particularly pronounced in large females though large males show this enlargement to a lesser extent. Chilton recognized two male morphs based on the male’s thumb shape and the expansion of the pereopods 5 and 6 (especially pereopod 6): conical thumb with “stout” pereopods 5 and 6 in his then named Podocerus frequens Chilton, 1883 and cubic thumb with “much expanded” pereopods 5 and 6 in his then named Podocerus latipes Chilton, 1884. However, Chilton (1884) had reservations about the two forms being different species, stating that Podocerus latipes “...may prove to be only a variety of P. frequens.” Chilton (1921) added some collecting information for these specimens, stating that they were fairly common in Lyttelton Harbour at the roots of Macrocystis and other seaweeds above low-water level. Chilton (1921) also pointed out that Stebbing (1906) had synonymized the two species as Jassa frequens (Chilton, 1883), regarding the cubic thumbed morph illustrated by Chilton (1884) to be the male and seemingly ignoring the conical thumbed male illustrated earlier by Chilton (1883). Chilton’s type material listed in Shaw & Poore (2016) were kindly lent by the Canterbury Museum along with material from other locations listed above. The single male specimen that Chilton (1883) illustrated in his type description and Plate III, Fig. 2 was of a very small conical thumb (his Fig. 2b) and this drawing does not correspond with the long conical thumb borne by the male slide mounted and designated type CMNZ 2015.149.86 (Fig. 8). Chilton (1883) did note in his new species description that “The process on the propodos of second gnathopoda of male varies in size in different specimens, and is often longer and more distinct than shown in fig. 2b.” The other two type slides CMNZ 2015.149.84 and 85 are whole body mounts of adult females, but neither corresponds with Chilton’s (1883) Fig. 2, either. Chilton’s label on CMNZ 2015.149.84 states that the specimen is a male but it is actually an adult female with setose brood plates. Chilton (1921) also illustrated the cubic thumbed type of male gnathopod 2 in Fig. 4A, p. 228 and this drawing matches the slide mounted male gnathopod 2 on Chilton’s slide CMNZ 2015.149.2161 from Brighton, Otago, New Zealand, collected Jan. 1890. Chilton’s (1921) Figs 4B, C correspond to dissected appendages of a female from Stewart Island, collected by H. B. Kirk (CMNZ 2015. 149.2116). Chilton’s (1921) Fig. 4D appears to be a pereopod 5 (not 6 as stated in the figure caption) but does not exactly match the pereopods on either of these slide mounts, showing fewer spines on the anterior margin of the basis. Jassa barnardi Stephensen, 1949 from Tierra del Fuego (type shown in Figs 10 and 11) is clearly the same as Chilton’s conical thumbed male (type male shown in Fig. 8). It has the same slender antennae, slender propodus of gnathopod 1, conical thumb on the propodus of gnathopod 2, minimal overlap of the merus over the carpus on pereopods 3 and 4 and wide merus and carpus on pereopods 5–7 with strong spination on the posterior margins. The same features of the urosome, not visible on Chilton’s slide mount of the type is evident in his un-mounted specimens preserved in alcohol (CMNZ 2015.149.575...604). This forces its synonymy under Ventojassa frequens. Additional illustrations of specimens from more recent collections are given here for comparison (Figs 12–15). Fig. 16 shows a graph of thumb length relative to body length in the conical thumbed and cubic thumbed males. The majority of specimens were taken from recent collections in New Zealand but they correspond well with specimens from Chilton’s collection. The contrast between the two morphs is shown in the much longer thumb in the conical thumbed males compared to the cubic thumbed males of the same body length. Within the longer conical thumbed group, there is no marked transition in thumb length, suggesting that thumb production occurs gradually over several molts rather than at the terminal molt as in Jassa (Conlan, 1989). For the cubic thumbed group, the largest specimen showed a longer thumb than the others, but more specimens are needed to determine variation. Chilton’s two morphs may indeed be separate species, but this requires DNA analysis as no non-sexually dimorphic characters could be found that separated the two morphs. While large males could be distinguished based on thumb morphology (conical vs cubic), and large females found with the cubic thumbed males had grossly enlarged pereopods 5 and 6 while large females found with conical thumbed males had less enlarged pereopods 5 and 6, smaller females and thumbless males could not be assigned to the two morphs. In addition, the two morphs appeared to co-occur, as evidenced by Chilton’s collection from Lyttelton, New Zealand (CMNZ 2015.149.575...604), which contained 3 conical thumbed males and 2 cubic thumbed males, as well as adult females with a range of moderately to grossly enlarged pereopods 5 and 6. There was also a juvenile Jassa gruneri Conlan, 1990 mixed in. One of the two cubic thumbed males in this collection is the one likely used by Chilton (1884) to illustrate the second gnathopod of the male Podocerus latipes in his type description, as this appendage had been torn off from the right side and the left gnathopod 2 corresponded with his Plate XIX, Fig. 2b. K. H. Barnard (1932) illustrated a conical thumbed male gnathopod 2 of a specimen named “ Jassa pusilla ” captured at Tristan da Cunha 30 Jan. 1926 at 40–46 m on a R. S. S. Discovery expedition. Stephensen (1949) noted that this was the same as his new species Jassa barnardi (herein transferred to V. frequens as stated above). He listed additional specimens to those examined for this study collected at Tristan da Cunha, Nightingale and Inaccessible Islands at 0–40 m depth. The specimens listed by Schellenberg (1931) from Valparaiso and Iquique, Chile (just south of Caleta Bruna) were possibly those examined for this paper and listed above. Schellenberg (1953) illustrated a cubic thumbed male gnathopod 2 and the urosome of a female from L̹deritz bay, Namibia (not seen). In his New Zealand study, J. L. Barnard (1972) collected V. frequens from washes of mixed species of low intertidal algae at stations in Dunedin, Lyttelton, Kaikoura, Wellington, and Leigh in addition to the cubic thumbed morph he illustrated from Huaroa Point and examined for this paper. These have not been seen but are likely to be the same cubic thumbed morph as otherwise, J. L. Barnard would likely have remarked on the difference. Additional unexamined collections of V. frequens from the Bay of Islands, Waitemata Harbour, Leigh, Hahei, and the Chatham Islands, New Zealand (0–12 m depth) are held at the Auckland Museum (AuM). Griffiths (1975) recorded two collections of V. frequens from False Bay, South Africa. No station number was given, so it could not be determined whether either of these corresponded to a single False Bay collection (station FAL 604G) that was lent by Griffiths for this study. This collection held a cubic thumbed morph. There are eight species of Ventojassa currently known (ordered by date of description and collection location): V. ventosa (J.L. Barnard, 1962) from California, V. crenulata Ledoyer, 1979 from Madagascar, V. dentipalma Kim & Kim, 1991 from Korea, V. helenae Vader & Myers, 1996 and V. zebra Vader & Myers, 1996 from Australia, V. beagle Alonso, 2012 from Argentina and V. palauensis Myers, 2013 from Palau. Of these, V. frequens may be closest to the Australian V. helenae and V. zebra which share the broad merus and carpus on pereopod 5. However, V. frequens has a narrower palm of gnathopod 1, a different ornamentation of the palm of gnathopod 2, pereopod 5 is without stridulating ridges, and pereopod 6 is more spinose and (especially in larger males and females) markedly stouter than pereopod 7. Common to other species of Ventojassa, V. frequens has a strongly produced interramal spinous process underlying the rami of uropods 1 and 2 but this is almost as long as the rami, where in other species it is typically shorter. Transferral of Jassa goniamera to Hemijassa Walker, 1907 and redescription of the genus Genus Hemijassa Walker, 1907. Hemijassa Walker, 1907, 38. Description of male. Maximum body length 22 mm. Head lobe: squared, angles acute. Antenna 1: accessory flagellum 2 articles, the second minute, only the second article setose. Antenna 2: stouter and longer than antenna 1, the filter setae progressively shorter; flagellum with all but the first article bearing spines on the posterior margin, first article considerably longer than any of the following articles. Maxilla 1: inner plate bearing a few short, fine setae; palp without setae at the base of article 1; article 2 with many scattered rows of facial setae distally. Gnathopod 1: coxa rectangular; propodus, palm defined by 4 spines located proximally of centre; dactyl not facially striated. Gnathopod 2: with a gill; coxa not deeper posteriorly; basis, filter setae simple or finely barbed and located on the anterolateral flange only; carpus less than 1/4 propodus length; propodus with a pronunced conical, multiply incised tooth below the dactyl hinge, and a larger acute thumb with 3 minute palmar defining spines at its tip, thumb setose on both inner and outer margins; dactyl shorter than the propodus, inner margin not expanded, tip resting on the tip of the thumb or between the thumb’s anterior margin and the palm; dactyl cusps reduced to small buttons interspersed with a few short setae. Pereopods 3 and 4: coxae rectangular; basis, margins more parallel than convex; merus slightly overlapping the carpus, anterior margin bearing discrete clusters of setae; propodus not posteriorly spinose. Pereopods 5–7: at least one basis posterodistally produced, anterior margin with a few short setae; merus and carpus, posterior margin no, Published as part of Conlan, Kathleen E., 2021, New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini, pp. 1-72 in Zootaxa 4921 (1) on pages 18-31, DOI: 10.11646/zootaxa.4921.1.1, http://zenodo.org/record/4496015, {"references":["Chilton, C. (1883) Further additions to our knowledge of the New Zealand Crustacea. Transactions and Proceedings of the New Zealand Institute, 15, 69 - 86.","Thomson, G. M. & Chilton, C. (1886) Critical list of the Crustacea Malacostraca of New Zealand. Transactions and Proceedings of the New Zealand Institute, 18, 141 - 159.","Shaw, M. D. & Poore, G. C. B. (2016) Types of Charles Chilton's Crustacea with comments on his collections in the Canterbury Museum. Records of the Canterbury Museum, 3 0, 25 - 51.","Chilton, C. (1884) Additions to the sessile-eyed Crustacea of New Zealand. Transactions and Proceedings of the New Zealand Institute, 16, 249 - 265.","Stebbing T. R. R. (1906) Amphipoda. I. Gammaridea. Das Tierreich, 21, 1 - 806.","Chilton, C. (1921) Some New Zealand Amphipoda. 2. Transactions and Proceedings of the New Zealand Institute, 53, 220 - 234.","Schellenberg, A. (1931) Gammariden und Caprelliden des Magellangebietes, Sudgeorgiens und der Westantarktis. Further Zoological Results of the Swedish Antarctic Expedition 1901 - 1903, 2 (6), 1 - 290.","Barnard, J. L. (1958) Index to the families, genera, and species of the gammaridean Amphipoda (Crustacea) (No. 19). Allan Hancock Foundation Occasional Papers, 19, 1 - 145.","Barnard, K. H. (1932) Amphipoda. Discovery Reports, 5, 1 - 326. https: // doi. org / 10.5962 / bhl. part. 27664","Stephensen, K. (1949) The Amphipoda of Tristan da Cunha. Results of the Norwegian Scientific Expedition to Tristan da Cunha 1937 - 1938, 3 (19), 1 - 61.","Barnard, J. L. (1972) The marine fauna of New Zealand: algae-living littoral Gammaridea Crustacea, Amphipoda). New Zealand Oceanographic Institute Memoir, 62, 1 - 216.","Griffiths, C. L. (1975) The Amphipoda of Southern Africa. 5. The Gammaridea and Caprellidea of the Cape Province west of Cape Agulhas. Annals of the South African Museum, 67 (5), 91 - 181.","Gonzalez, E. (1991) Actual state of gammaridean taxonomy and catalogue of species from Chile. Hydrobiologia, 223, 47 - 68. https: // doi. org / 10.1007 / BF 00047628","Conlan, K. E. (1989) Delayed reproduction and adult dimorphism in males of the amphipod genus Jassa (Corophioidea: Ischyroceridae): an explanation for systematic confusion. Journal of Crustacean Biology, 9, 601 - 625. https: // doi. org / 10.1163 / 193724089 X 00629","Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288","Schellenberg A. (1953) Erganzungen zur Amphipodenfauna Sudwest-Afrikas nebst Bemerkungen uber Brutraumbildung. Mitteilungen aus dem Museum f ʾ r Naturkunde in Berlin. Zoologisches Museum und Institut f ʾ r Spezielle (Berlin), 29 (1), 107 - 126. https: // doi. org / 10.1002 / mmnz. 19530290105","Barnard, J. L. (1962) Benthic marine Amphipoda of Southern California: Families Aoridae, Photidae, Ischyroceridae, Corophiidae, Podoceridae. Pacific Naturalist, 3 (1), 3 - 72.","Ledoyer, M. (1979) Les gammariens de la pente externe du Grand Recif de Tulear (Madagascar) (Crustacea Amphipoda). Memoir Del Museo Civico Di Storia Naturale Di Verona, IIa Serie, Sezione Scienze Della Vita, 2, 1 - 149.","Kim, W. & Kim, C. B. (1991) The marine amphipod crustaceans of Ulreung Island, Korea: part I. The Korean Journal of Zoology, 34 (2), 232 - 252.","Vader, W. & Myers, A. A. (1996) Amphipods living in association with hermit crabs in SE Australia. I. Five new Ischyroceridae. Bollettino del Museo Civico di Storia Naturale di Verona, 20, 263 - 292.","Alonso G. M. (2012) Amphipod crustaceans (Corophiidea and Gammaridea) associated with holdfasts of Macrocystis pyrifera from the Beagle Channel (Argentina) and additional records from the Southwestern Atlantic. Journal of Natural History, 46 (29 - 30), 1799 - 1894. https: // doi. org / 10.1080 / 00222933.2012.692825","Myers, A. A. (2013) Amphipoda (Crustacea) from Palau, Micronesia: Families Dexaminidae, Eusiridae, Hyalidae, Ischyroceridae, Leucothoidae and Lysianassidae. Zootaxa, 3731 (3), 301 - 323. https: // doi. org / 10.11646 / zootaxa. 3731.3.1","Walker, A. O. (1907) Crustacea. III. Amphipoda. National Antartic Expedition 1901 - 1904. Natural History 3, 1 - 39.","Walker, A. O. (1903) Amphipoda of the \" Southern Cross \" Antarctic Expedition. Journal of the Linnean Society of London, Zoology, 29 (187), 38 - 64. https: // doi. org / 10.1111 / j. 1096 - 3642.1903. tb 00425. x","Norman, A. M. (1905) VIII-Revised nomenclature of the species described in Bate and Westwood's ' British Sessile-eyed Crustacea'. Journal of Natural History, 16 (91), 78 - 95.","Walker, A. O. (1911) Notes on Jassa falcata (Mont.). Transactions of the Liverpool Biological Society, 25, 67 - 72.","Pfeffer, G. (1888) Die krebse von S ʾ d-Georgien nach der ausbeute der Deutschen station 1882 - 83. 2. Die Amphipoden. Hamburg Wissenschafftlichen Anstalten Jahrbuch, 5, 75 - 142. https: // doi. org / 10.5962 / bhl. title. 10084","Bellan-Santini, D. (1972) Invertebres marins des XIIeme et XVeme Expeditions Antarctiques Francaises en Terre Adelie. 10. Amphipodes Gammariens. Tethys, 4, 157 - 238.","Thurston, M. H. (1974 b) The Crustacea Amphipoda of Signy Island, South Orkney Islands. British Antarctic Survey Scientific Reports, 71, 1 - 133.","Lowry, J. K. & Bullock, S. (1976) Catalogue of the Marine Gammaridean Amphipoda of the Southern Ocean. Bulletin of the Royal Society of New Zealand, 16, 1 - 187.","Sexton, E. W. & Reid, D. M. (1951) The life-history of the multiform species Jassa falcata (Montagu) (Crustacea Amphipoda) with a review of the bibliography of the species. Journal of the Linnean Society of London, Zoology, 42 (283), 29 - 91. https: // doi. org / 10.1111 / j. 1096 - 3642.1951. tb 01852. x","Borowsky, B. (1985) Differences in reproductive behavior between two male morphs of the amphipod crustacean Jassa falcata Montagu. Physiological Zoology, 58, 497 - 502. https: // doi. org / 10.1086 / physzool. 58.5.30158577"]}

Hemijassa goniamera (Walker, 1903) (Figs 17–21) Jassa goniamera Walker, 1903, 61, 62, Plate 11, Figs 98–107 (part, according to Thurston (1974b), specimens less than 5 mm long are Parajassa georgiana); Stebbing, 1906, 739; Schellenberg, 1931, 253; Nicholls, 1938, 128; Stephensen, 1947, 73, Fig. 24; J. L. Barnard, 1958, 85; Lowry & Bullock, 1976, 75; Thurston, 1974b, 100. Hemijassa goniamera Walker, 1907, 38. Jassa falcata:? Chilton, 1912, 511; not Schellenberg, 1926, 383; Sexton & Reid, 1951, 72, 75, 77–78, 81–83, 85, 86; Bellan-Santini, 1972, 191. Jassa ingens: K. H. Barnard, 1932, 242 Fig. 151C (in part). Description of male. Lectotype (here designated): Length 18.3 mm. Antenna 2: overlapped by antenna 1 to midway along article 5; article 5, posterior marginal setae very short and simple, minute compared with those of the female; flagellum 8 articles, the last 1/2 the size of the second last, article 1 46% of full length. Mandible: palp articles 2 and 3 with a dorsal fringe of setae; raker spines 6 right, 8 left. Gnathopod 1: coxal margins, anterior 72% of dorsal length, ventral margin straight; basis, anterior margin with a fringe of long setae laterally, posterior margin with many setae also, which are just as long and wide ranging as on the anterior margin, but more scattered; carpus, length 64% of propodus length, posterior lobe 47% of anterior margin length, anterodistal setal cluster short, 25% of the anterior margin length; propodus, palm convex; dactyl cusped along the full length, without facial striations. Gnathopod 2: coxal margins, anterior 87% and posterior 100% of ventral length, ventral margin straight; basis, anterolateral flange with a row of long, simple filter setae (setae about 1/2 article width); carpus, posterior lobe with a cluster of distal setae; propodus, anterior margin with a series of clusters of short setae (setae about 1/2 basis width). Pereopod 3: basis narrower than the gnathopod 1 basis, anterior margin shallowly concave; merus, anterior margin with a row of setae along its length, article width 45% of length; carpus barely 10% overlapped by merus; propodus width 40% of length. Pereopods 5–7: basis posterodistally produced, anterior margin with a few short setae; merus and carpus, posterior margin not spinose. Uropod 1: peduncle, posteroventral spinous process underlying 41% of the inner ramus, inner and outer rami with 12 and 13 mid-dorsal spines respectively, not terminating in a fringe of cusps ventral to the apical spine group. Uropod 2: peduncle, posteroventral spinous process underlying 25% of the inner ramus. Uropod 3: inner ramus not mid-dorsally spinose. Condition. Left antenna 1, tip of flagellum missing, without left pereopod 7. Right appendages, telson and mouthparts slide mounted. Description of adult female. Paralectotype: Length 19.9 mm. As in the genus description. Condition. With all appendages. Right appendages, telson and mouthparts slide mounted. Variation. Maximum body length: male 22 mm, female 20 mm. Hemijassa goniamera exhibits sexual dimorphism in the antenna 2 and gnathopod 2. The antenna 2 development appears to be much like that in species of Jassa, with antennae long with short filter setae in large males compared to females and small males (Figs 17, 18 and 20). The palm of gnathopod 2 is sinuous in small males, but with a ledge or tooth in large males (Fig. 20). In females the palm remains sinuous at all sizes (Fig. 18). Type material examined. Lectotype, &male;, NHM 1987:515, Cape Adare, McMurdo Sound, Ross Sea, Antarctica (71°17ʹS, 170°14ʹE), “Southern Cross” Expedition, 5 November 1902. Paralectotypes, 5 &male;&male;, 9 adult &female;&female;, 6 small (juvenile?) males and 10 juvenile females, NHM 1902.11.5:6–10 (part), same location. Other material examined. South Sandwich Islands: Visokoi I., 13 Nov. 1908, 60– 100 m, C. A. Larsen, coll., 1 &female; (UiO F2968). South Shetland Islands, Antarctica: off Cape Bowles, Clarence I., 23 Feb. 1927, ‘ Discovery’ station 170, 342 m, 5 &male;&male;, 8 &female;&female; (NHM 1936:11.2:2411–2426 (part)); Bransfield Strait, 2 Mar. 1927, ‘ Discovery’ station 175, 200 m, 1 &male; (NHM 1936.11.2: 2411–2428 (part). Graham Region, Antarctica: Seymour I. (64°20ʹS, 56°38ʹW), 16 Jan. 1902, 150 m, Svenska Sydpolarexp. 1901– 1903, No. 5, 3 juveniles (SNM) and 10 juveniles (NRM 3679); SW of Snow Hill I., (64°36ʹS, 57°42ʹW), 20 Jan. 1902, 125 m, Svenska Sydpolarexp. 1901–1903, No. 6, 1 &male;, 1 &female;, 1 juvenile (NRM 3680). Ross Sea, Antarctica: Coulman I., 13 Dec. 1902, 183 m, 1 &male;, 1 &female; (NHM 1907.6.6:410–415); Flagon Pt., Winter Quarters Bay, McMurdo Sound, 23 Jan. 1903, ‘ Discovery’ Expedition, 1 &male;, 1 &female;, 1 juvenile (NHM 1907.6.6.414–415); Flagon Pt., Winter Quarters Bay, McMurdo Sound, 17 Jan. 1903, ‘ Discovery’ Expedition, 3 &female;&female; (NHM 1907.6.6:410– 415). Weddell Sea, Antarctica: Cap Norvegia, (71°2ʹS, 12°W), 17 Feb. 1930, Norvegia Expedition, Riiser-Larsen, 1 &female; (UiO); off Kapp Norvegia (70.0145°S, 10.00806°W), 30 Jan. 1998, Agassiz trawl beginning at 246 m, C. de-Broyer and Y. Scailteur, coll., Polarstern EASIZ II Expedition (Ant XV /3), 1 &male; (RBINS IG28520); off Kapp Norvegia (70.01461°S, 10.00794°W), 31 Jan. 1998, Agassiz trawl beginning at 248 m, C. deBroyer and Y. Scailteur, coll., Polarstern EASIZ II Expedition (Ant XV /3), 2 &male;&male; (RBINS IG28252). Commonwealth Bay, Antarctica: 21 Dec. 1913, 10– 120 m, Australasian Antarctic Expedition, 1 &male; (AM P.18415). Terre Adélie, Antarctica: Archipel de Pointe Géologie, 2 Jan.1965, 110– 130m, fond à bryozoaires, hydraires, spongiaires et alcyonaires, P.M. Arnaud, coll., station TA-D102 (D. Bellan-Santini loan). Remarks. Schellenberg (1926) may have recorded H. goniamera at Gauss-Station (Kaiser Wilhelm II Land) during the Deutsche S̹dpolar-Expedition 1901–1903, collected on August 12, 1902 and named it Jassa falcata. Other specimens listed as “ J. falcata ” may have been P. wandeli, judging by their size and collection location. One collection of “ J. falcata ” from Terre Adélie, Antarctica and listed in Bellan-Santini (1972) was examined and found to be H. goniamera. It is likely that the other three collections listed therein (not seen) are also H. goniamera, judging by the size of the specimens (7–17 mm) and depth of collection (15–140 m). Hemijassa goniamera is only known subtidally and can be found clinging to bryozoans and hydroids (Dauby et al. 2001). Trace metal levels are relatively low in H. goniamera and well within the range of other Antarctic amphipods (Keil et al. 2008). Transferral of Jassa wandeli and J. multidentata to Pleojassa n. gen. with addition of P. moorei n. sp., P. lowryi n. sp. and P. orientalis n. sp. Genus Pleojassa n. gen. Description of male. Maximum body length 10.8 mm. Head lobe: squared, dorsal angle more acute, lower angle lobe more rounded. Antenna 1: accessory flagellum 2 articles, the second minute, setose only distally. Antenna 2: stouter and longer than antenna 1, setation variable, filter setae shorter and sparser in larger individuals, flagellum spination variable, first article considerably longer than following articles. Maxilla 1: inner plate bearing a few short, fine setae; palp without setae at the base of article 1, article 2 with 1 row of facial setae. Gnathopod 1: coxa rectangular; carpus, anterior margin length Gnathopod 2: without a gill; coxa not deeper posteriorly; basis without filter setae; carpus a quarter of propodus length or less, lobe apically setose; propodus without anteroproximal setae, hinge tooth rectangular cuboid or conical, shallowly or deeply bifid, or multiply incised, palm concave to the single medial defining spine, there produced or not into a short “hook” or long thumb; dactyl shorter than the propodus, variably expanded at the hinge tooth, tip apposing the defining spine, or if thumb present, its posterior margin, cusps reduced and interspersed with short setae. Pereopod 3: coxa deepest centrally or slightly posterior of centre; basis a little slenderer in larger individuals; merus, anterior margin bearing well-spaced single or clustered setae; carpus, overlap by merus variable; propodus not posteriorly spinose. Pereopods 5–7: basis variably posterodistally produced or not produced, anterior margin spinose or setose; merus not posterodistally spinose; carpus with a cluster of spines posterodistally at least on pereopod 5; propodus not strongly expanded anteriorly; dactyl not facially serrated, posterior (outer) margin not cusped distally, anterior (inner) margin, setation variable. Pleopods: rami very short, length ± depth of the pleon, each with 2 coupling hooks. Urosome: segment 1 with dorsal pair of erect setae. Uropod 3: peduncle mid-ventrally setose, without mid-dorsal spines, but with a crown of spines dorsomedially at the insertion of the rami and a cluster of setae distolaterally; outer ramus not setose mid-dorsally, tipped by a basally immersed, dorsally recurved spine and associated seta and serrations, cusps variable, but never as on Jassa; inner ramus with or without a spine or spines mid-dorsally in addition to the single apical spine. Telson: each dorsolateral corner with a pair of cusps accompanied by setae (2 long, simple, and 2 short, plumose) but not spines. Description of adult female. Maximum body length 9.8 mm. Character states as in the male except as follows. Brood plates: broad, setae well separated, abundant, at least some hook-tipped. Antenna 2: peduncle, posterior filter setae long, not shorter in larger individuals. Gnathopod 2: propodus much larger and different in shape from propodus of gnathopod 1, palm concave, defined by a single medial spine and without a thumb; dactyl tip apposing the defining angle and spine, dactyl cusps strong. Pereopod 3: basis somewhat broader than in the male. Variation. Antenna 2 peduncular setal change appears to be similar to that of Jassa, with the male’s setae shorter in larger specimens and the female’s remaining long. Male gnathopod 2 thumbing is not homologous, however, because the thumb develops at the palmar defining spine rather than distal to it. Consequently the thumb’s setation pattern is quite different. Type species. Jassa wandeli Chevreux, 1906. Included species. Pleojassa wandeli (Chevreux, 1906), P. multidentata (Schellenberg, 1931), P. moorei n. sp., P. lowryi n. sp. and P. orientalis n. sp. Remarks. Distinguishing features from Jassa are a single spine defining the palm of gnathopod 2, and hence different thumb setation, closure of the second gnathopod’s dactyl at, rather than distal to, the defining spine, lack of a gnathopod 2 gill, reduced pleopods and lack of a double cusp on the uropod 3 outer ramus. The males of P. wandeli and P. multidentata produce a long thumb if sufficiently larger than the adult female and thus would superficially appear to be a Jassa. Thumb development appears from specimens to be a progressive transformation, not at a terminal molt, however (although this has not been tested experimentally as it has for Jassa). Males of P. orientalis probably also produce a thumb as this species closely resembles P. multidentata. Pleojassa moorei and P. lowryi are not known to produce thumbs in the males and sufficient specimens were available to find males of similar or larger size than adult females to indicate that the males were adult as well. However, the five species resemble each other in characters that are conservative within Jassa, such as the tendency toward setal reduction in the antenna 2 of the male compared to the female, and in similar morphologies of the mouthparts, gnathopod 1, female gnathopod 2, female brood plates and third uropod hooking. Key to World species of Pleojassa (both sexes) 1 Uropod 1, posteroventral peduncular spinous process nearly as long as the outer ramus. Gnathopod 1, carpus without a seta at the anterodistal junction of the propodus. Female gnathopod 2, palmar setae not densely plumose (Fig. 22)....................................................................................................... P. moorei n.sp. - Uropod 1, posteroventral peduncular spinous process ½ to ¾ the length of the outer ramus. Gnathopod 1, carpus with or without a single seta or cluster of setae at the anterodistal junction of the propodus. Female gnathopod 2, palm bearing abundant plumose setae (Figs 27 and 28).......................................................................... 2 2 Pereopods 3 and 4, carpus nearly fully overlapped by the merus (Fig. 25). Female body size at maturity 2.5–5.1 mm. Gnathopod 2, propodus, palm densely plumose in both sexes; larger male ~ 3 mm body length or more, palm defined by a small hook but not by a thumb (Fig. 25)..................................................................... P. lowryi n.sp. - Pereopods 3 and 4, carpus 1/2 to 3/4 overlapped by the merus (Figs 27–29). Female body size at maturity 5.9–9.8 mm. Gnathopod 2, propodus, only the female palm densely plumose; larger male ~ 6 mm body length or more, palm defined by a thumb (Fig. 30)............................................................................................ 3 3 Female gnathopod 2, propodus, dactylar hinge tooth shallow (Fig. 33). Antenna 2, large male and female, posterior margin of article 5 and flagellum plumose (Fig. 33)............................................ P. wandeli (Chevreux, 1906) - Female gnathopod 2, propodus, dactylar hinge tooth deep (Figs 27 and 28). Antenna 2, adult female and comparably sized male, posterior margin of article 5 and flagellum not plumose (Figs 27 and 28)......................................... 4 4 Gnathopod 1, carpus with a single or cluster of setae at the anterodistal junction of the propodus (Fig. 27). Known only from South Georgia (Fig. 2)..................................................... P. multidentata (Schellenberg, 1931) - Gnathopod 1, carpus without a single or cluster of setae at the anterodistal junction of the propodus (Fig. 28). Known only from Macquarie Island (Fig. 2).................................................................. P. orientalis n. sp. Genus Pleojassa n. gen. Description of male. Maximum body length 10.8 mm. Head lobe: squared, dorsal angle more acute, lower angle lobe more rounded. Antenna 1: accessory flagellum 2 articles, the second minute, setose only distally. Antenna 2: stouter and longer than antenna 1, setation variable, filter setae shorter and sparser in larger individuals, flagellum spination variable, first article considerably longer than following articles. Maxilla 1: inner plate bearing a few short, fine setae; palp without setae at the base of article 1, article 2 with 1 row of facial setae. Gnathopod 1: coxa rectangular; carpus, anterior margin length Gnathopod 2: without a gill; coxa not deeper posteriorly; basis without filter setae; carpus a quarter of propodus length or less, lobe apically setose; propodus without anteroproximal setae, hinge tooth rectangular cuboid or conical, shallowly or deeply bifid, or multiply incised, palm concave to the single medial defining spine, there produced or not into a short “hook” or long thumb; dactyl shorter than the propodus, variably expanded at the hinge tooth, tip apposing the defining spine, or if thumb present, its posterior margin, cusps reduced and interspersed with short setae. Pereopod 3: coxa deepest centrally or slightly posterior of centre; basis a little slenderer in larger individuals; merus, anterior margin bearing well-spaced single or clustered setae; carpus, overlap by merus variable; propodus not posteriorly spinose. Pereopods 5–7: basis variably posterodistally produced or not produced, anterior margin spinose or setose; merus not posterodistally spinose; carpus with a cluster of spines posterodistally at least on pereopod 5; propodus not strongly expanded anteriorly; dactyl not facially serrated, posterior (outer) margin not cusped distally, anterior (inner) margin, setation variable. Pleopods: rami very short, length ± depth of the pleon, each with 2 coupling hooks. Urosome: segment 1 with dorsal pair of erect setae. Uropod 3: peduncle mid-ventrally setose, without mid-dorsal spines, but with a crown of spines dorsomedially at the insertion of the rami and a cluster of setae distolaterally; outer ramus not setose mid-dorsally, tipped by a basally immersed, dorsally recurved spine and associated seta and serrations, cusps variable, but never as on Jassa; inner ramus with or without a spine or spines mid-dorsally in addition to the single apical spine. Telson: each dorsolateral corner with a pair of cusps accompanied by setae (2 long, simple, and 2 short, plumose) but not spines. Description of adult female. Maximum body length 9.8 mm. Character states as in the male except as follows. Brood plates: broad, setae well separated, abundant, at least some hook-tipped. Antenna 2: peduncle, posterior filter setae long, not shorter in larger individuals. Gnathopod 2: propodus much larger and different in shape from propodus of gnathopod 1, palm concave, defined by a single medial spine and without a thumb; dactyl tip apposing the defining angle and spine, dactyl cusps strong. Pereopod 3: basis somewhat broader than in the male. Variation. Antenna 2 peduncular setal change appears to be similar to that of Jassa, with the male’s setae shorter in larger specimens and the female’s remaining long. Male gnathopod 2 thumbing is not homologous, however, because the thumb develops at the palmar defining spine rather than distal to it. Consequently the thumb’s setat, Published as part of Conlan, Kathleen E., 2021, New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini, pp. 1-72 in Zootaxa 4921 (1) on pages 31-39, DOI: 10.11646/zootaxa.4921.1.1, http://zenodo.org/record/4496015, {"references":["Walker, A. O. (1903) Amphipoda of the \" Southern Cross \" Antarctic Expedition. Journal of the Linnean Society of London, Zoology, 29 (187), 38 - 64. https: // doi. org / 10.1111 / j. 1096 - 3642.1903. tb 00425. x","Thurston, M. H. (1974 b) The Crustacea Amphipoda of Signy Island, South Orkney Islands. British Antarctic Survey Scientific Reports, 71, 1 - 133.","Stebbing T. R. R. (1906) Amphipoda. I. Gammaridea. Das Tierreich, 21, 1 - 806.","Schellenberg, A. (1931) Gammariden und Caprelliden des Magellangebietes, Sudgeorgiens und der Westantarktis. Further Zoological Results of the Swedish Antarctic Expedition 1901 - 1903, 2 (6), 1 - 290.","Nicholls, G. E. (1938) Amphipoda Gammaridea. Australasian Antarctic Expedition 1911 - 14. Scientific Reports, Series C. Zoology and Botany,","Stephensen, K. (1947) Tanaidacea, Isopoda, Amphipoda and Pycnogonida. Det Norske Videnskaps-Akademi I Oslo, Scientific Results of the Norwegian Antarctic Expeditions 1927 - 28 et sqq., Instituted and Financed by Consul Lars Christensen, 27, 1 - 90.","Barnard, J. L. (1958) Index to the families, genera, and species of the gammaridean Amphipoda (Crustacea) (No. 19). Allan Hancock Foundation Occasional Papers, 19, 1 - 145.","Lowry, J. K. & Bullock, S. (1976) Catalogue of the Marine Gammaridean Amphipoda of the Southern Ocean. Bulletin of the Royal Society of New Zealand, 16, 1 - 187.","Walker, A. O. (1907) Crustacea. III. Amphipoda. National Antartic Expedition 1901 - 1904. Natural History 3, 1 - 39.","Chilton, C. (1912) The Amphipoda of the Scottish National Antarctic Expedition. Transactions of the Royal Society of Edinburgh, 48 (3), 455 - 520. https: // doi. org / 10.1017 / S 0080456800002957","Schellenberg, A. (1926) Die Gammariden der Deutschen Sudpolar-Expedition 1901 - 1903. Deutsche Sudpolar-Expedition 1901 - 1903, 18 (10), 235 - 414.","Sexton, E. W. & Reid, D. M. (1951) The life-history of the multiform species Jassa falcata (Montagu) (Crustacea Amphipoda) with a review of the bibliography of the species. Journal of the Linnean Society of London, Zoology, 42 (283), 29 - 91. https: // doi. org / 10.1111 / j. 1096 - 3642.1951. tb 01852. x","Barnard, K. H. (1932) Amphipoda. Discovery Reports, 5, 1 - 326. https: // doi. org / 10.5962 / bhl. part. 27664","Bellan-Santini, D. (1972) Invertebres marins des XIIeme et XVeme Expeditions Antarctiques Francaises en Terre Adelie. 10. Amphipodes Gammariens. Tethys, 4, 157 - 238.","Dauby, P., Scailteur, Y. & De Broyer, C. (2001) Trophic diversity within the eastern Weddell Sea amphipod community. Hydrobiologia, 443, 69 - 86. https: // doi. org / 10.1023 / A: 1017596120422","Keil, S., De Broyer, C. & Zauke, G. P. (2008) Significance and interspecific variability of accumulated trace metal concentrations in Antarctic benthic crustaceans. International Review of Hydrobiology, 93 (1), 106 - 126. https: // doi. org / 10.1002 / iroh. 200711006","Chevreux, E. (1906) Crustaces Amphipodes. In: Expedition Antarctique Francaise (1903 - 1905) commandee par le Dr. Jean Charcot. Sciences naturelles: documents scientifiques. Masson et Cie, Paris, pp. 1 - 100."]}

Tribe Ischyrocerini Kr��yer, 1838 Supplementary Table S2 Type genus. Ischyrocerus Kr��yer, 1838 Diagnosis (with changes from Just (2017) in bold). Antennae: slender, antenna 1 with accessory flagellum (occasionally vestigial). Mandible: palp with 3 articles, the third expanded distally (occasionally similar in shape to the second). Coxae 1���4: progressively deepening, subrectangular to oval (occasionally coxa 1 much smaller than and mostly obscured by coxa 2 and differing in shape), margins entire. Gnathopod 1: carpus shorter than the propodus (occasionally longer), propodus oval to weakly subchelate. Gnathopod 2: propodus in adult male (and occasionally in the female) moderately to strongly enlarged compared to gnathopod 1, of varying shape (occasionally hardly modified). Pereopods 3���4: merus moderately to fully overlapping the carpus anteriorly, dactyl shorter than the carpus (occasionally longer ). Pereopods 5���7: of similar form, increasing in length backwards (occasionally 6 larger than 5 and 7). Urosomites: 1���3 free. Uropods 1 and 2: peduncle without distoventral corona of spines, with 2 subequal rami with or without an underlying peduncular spinous process (occasionally uropod 2 outer ramus modified). Uropod 3: peduncle long (occasionally short), broad proximally, narrow distally, biramous (occasionally uniramous), outer ramus terminating in cusps and/or spine(s). Telson: entire, with one to many dorsally or apically projecting setae or spines. Component genera. Jassa Leach, 1814; Ischyrocerus Kr��yer, 1838; Paradryope Stebbing, 1888; Microjassa Stebbing, 1899; Parajassa Stebbing, 1899; Hemijassa Walker, 1907 ; Isaeopsis K.H. Barnard, 1916; Pseudischyrocerus Schellenberg, 1931; Bathyphotis Stephensen, 1944; Ventojassa J.L. Barnard, 1970; Neoischyrocerus Conlan, 1995; Scutischyrocerus Myers, 1995; Ruffojassa Vader & Myers, 1996; Veronajassa Vader & Myers, 1996; Alatajassa Conlan, 2007; Myersius Souza-Filho & Serejo, 2014; Pleojassa n. gen.; Plumulojassa n. gen. Changes to Ischyrocerus and Neoischyrocerus Ischyrocerus is primarily a cold water, Northern Hemisphere genus, captured from deep trawls (Stephensen 1944; Gurjanova 1951) as far north as the high Arctic, but also found in the intertidal and shallow subtidal zone (J.L. Barnard 1962). It has been extensively found in the Southern Hemisphere as well, though mostly in warmer waters (Myers 1995, 1997; Just 2009). This large genus requires revision and may prove to be less cosmopolitan than previously thought by J.L. Barnard & Karaman (1991). Three genera have been created for warm water Ischyrocerus -like species: Neoischyrocerus Conlan, 1995 (4 species), Coxischyrocerus Just, 2009 (2 species) and Tropischyrocerus Just, 2009 (2 species). These genera embrace species in which the male develops an enormously lengthened and pendulous gnathopod 2 (about 200���300% the length of gnathopod 1) with an anteriorly rounded ischium and a very long propodus with the palm nearly the full length of the propodus, and the proximal end of the palm marked by a bulge next to the carpus (the S. Californian N. claustris (J.L. Barnard, 1969), N. chinipa (J.L. Barnard, 1979) from the Galapagos and Pacific Panama, N. vidali Ortiz & Lalana, 2002 from the Cuban Caribbean, C. inexpectatus (Ruffo, 1959) from the Mediterranean Sea and T. socia (Myers, 1989) from Bora Bora), a tooth-like projection (e.g., N. lilipuna (J.L. Barnard, 1970) from Hawaii and T. pugilus Just, 2009 from Australia), or with neither (e.g., C. rhombocoxus Just, 2009 from Australia). The dactyl may be the full length of the propodus or shorter, the length growth related. By comparison, the female���s gnathopods are similarly sized with the second only slightly larger than the first. Other commonalities are antennae with long filtering setae that are not pediform or sexually dimorphic, a 2-articulate accessory flagellum with the second article minute, pereopods 3 and 4 with little overlap of the merus over the carpus, a well developed peduncular spinous process under the rami of uropod 1, a spiny peduncle of uropod 3 with the outer ramus bearing a row of minute cusps and the inner ramus tipped by a small spine, and the telson with a pair of strong, dorsally projecting spines. The difficulty with these genera is where species cross the generic boundaries. Examples are: enlarged coxa 2 relative to coxa 1 in the adult male (C. rhombocoxus and N. claustris), similar gnathopod propodus appearance as noted above, and similar female gnathopod palms (convex in all species in the three genera except for T. pugilus), pereopod 3 and 4 propodus posteriorly spinose (N. lilipuna, N. vidali, T. socia and C. inexpectatus). The generic-level differences among the genera therefore recede into issues of sexual variation (e.g., enlargement of coxa 2 relative to coxa 1 that was used to define Coxischyrocerus but also occurs in Neoischyrocerus, or the modified pereopod 5 basis shape in adult males of C. rhombocoxus and C. inexpectatus). Therefore, Coxischyrocerus Just, 2009 and Tropischyrocerus Just, 2009 are herein merged into the senior genus Neoischyrocerus Conlan, 1995. Myers (1995, 1997) noted the need for diminutive Indo-Pacific species placed at that time in Ischyrocerus or Jassa to be placed in their own genus and these are also included, as noted below. Genus Neoischyrocerus n. comb. Supplementary Table S3 Type species. N. claustris J.L. Barnard, 1969 Diagnosis. (with differences from Ischyrocerus in bold). Body length at maturity 1���2 mm (usually), rarely 4���6 mm. Tropical and warm temperate distribution, collected from algae, sponges, corals or from a spiny lobster, 0���16 m, 9��� 40��N and 5��� 34��S. Pereon: dorsally smooth (most species), ridged or carinate (some species). Antenna 1: accessory flagellum 2 articles (second minute), projecting forward or flush with the flagellum; antennae 1 and 2 peduncles subequal in width or antenna 2, 10% wider (based on comparison of antenna 1 peduncle article 2 with antenna 2 peduncle article 4), peduncular setae and setal pattern similar to antenna 1, or slightly shorter, not plumose. Gnathopod 2, adult male: 190���350% the length of gnathopod 1, basis and propodus especially elongate; coxa 1, 60���110% the depth of coxa 2; basis concave or sinuous; ischium anteriorly rounded; propodus often slender (posterior length 180���400% of central width), palm nearly the full length of the propodus, often with a bulge or tooth defining it proximally at the junction of the carpus (sometimes palm continuous with the carpus), sometimes centrally toothed instead and with shallow bulge or teeth at the junction of the dactyl; dactyl half or nearly the full length of the propodus. Gnathopod 2, juvenile male: shorter than the adult male gnathopod 2, palm bearing 1���2 strong spines about midway along the length of the propodus, dactyl ending at the spines. Gnathopod 2, female: only slightly larger than gnathopod 1, palm of the propodus convex (usually) or shallowly concave (rarely). Pereopods 3 and 4: propodus, posterior margin bearing spines or setae; coxa 4, posterior margin straight, not shallowly concave. Pereopod 5, male: similar to but shorter than pereopods 6 and 7 or variously modified with posteriorly concave basis or posteriorly expanded and spinose merus. Uropod 1: peduncle with short ventrodistal spinous process underlying the rami, length ~15���35% of the outer ramus length. Uropod 3: peduncle bearing 1���2 rows of spines dorsally, ending in a single spine at the distal margin, but without a corona of spines around the margin or setae; rami without spines mid-dorsally, outer ramus subequal to or shorter than the inner and bearing 3���8 minute dorsal cusps apically, without (rarely with) a small apical straight spine. Component species (with transferred species in bold). Ischyrocerus longimanus (Haswell, 1879) (Australia); I. parvus Stout, 1913 (California); I. carinatus K.H. Barnard, 1916 (South Africa); I. gorgoniae K.H. Barnard, 1940 (South Africa); I. ctenophorus Schellenberg, 1953 (South Africa); Coxischyrocerus inexpectatus (Ruffo, 1959) (Mediterranean, Red Sea?); N. claustris J.L. Barnard, 1969 (California); N. lilipuna J.L. Barnard, 1970 (Hawaii); I. oahu J.L. Barnard, 1970 (Hawaii); I. oahu oahu J.L. Barnard, 1970 (Hawaii); N. chinipa J.L. Barnard, 1979 (Galapagos Islands and Panama); I. oahu armatus Ledoyer, 1979 (Madagascar); Tropischyrocerus socia (Myers, 1989) (Bora Bora); I. mediodens Myers, 1995 (Papua New Guinea); I. parma Myers, 1995 (Papua New Guinea); I. apiensis Myers, 1997 (Samoa); N. vidali Ortiz & Lalana, 2002 (Cuba); C. rhombocoxus Just, 2009 (Australia); T. pugilus Just, 2009 (Australia). Remarks. Species of Ischyrocerus were transferred to Neoischyrocerus if they demonstrated at least one key character (grossly enlarged and pendulous male gnathopod 2 similar in shape to that of others in the genus; dactyls with comb-like striae as noted in J.L. Barnard (1970), Conlan (1995) and Ortiz & Lalana (2002); similar spination on uropod 3). Presence or absence of these striae were not mentioned by other authors, therefore questioning as to whether this character had been looked for. Mouthpart characteristics were not widely described, but may be useful for generic definition, especially the clavate vs slenderer shape of the mandibular palp and the presence/absence of a long apical seta on the maxilla 1 inner plate. Excluded but uncertain generic status. Ischyrocerus kapu J.L. Barnard, 1970 from Hawaii. The author based the generic assignment on a single male specimen. He noted its resemblance to N. lilipuna but also considered that it should be in a new genus. On balance, though, he assigned it to Ischyrocerus but noted that this was based on limited information because the specimen lacked antennae and pereopods and the female was also unknown. The male���s gnathopod 2 is unusual in having a long conical extension of the merus underneath the propodus, a feature that is not known for either Ischyrocerus or Neoischyrocerus. Myers (1995) stated that I. kapu is congeneric with other species being transferred to Neoischyrocerus. The male���s propodus is wider than in other members of Neoischyrocerus, but its uropod 3 resembles other species of Neoischyrocerus rather than Ischyrocerus. Further material demonstrating the species��� complete morphology is required before it can be confidently transferred to Neoischyrocerus or to a new genus. Genus Ischyrocerus n. comb. Supplementary Table S4 Type species. Ischyrocerus anguipes Kr��yer, 1838 Diagnosis (with differences from Neoischyrocerus in bold). Body length at maturity 2���18 mm, though most species are> 5 mm long at adulthood. Primarily known from the Northern Hemisphere in cold temperate to polar waters from 32��N (La Jolla, California; J.L. Barnard 1969) to 81��N in the Arctic Ocean (Stephensen 1944), collected from algae, hydroids, crabs or substrate unknown, 1 to ~ 2000 m. Widely known in Europe but not in the Southern Hemisphere, although one species was found at 42��S off of Chile (J.L. Barnard 1964). Pereon: dorsally smooth (most species), ridged or carinate (some species). Antenna 1: accessory flagellum 2 articles (second minute), flush with the flagellum or rarely projecting forward; antenna 2 peduncle article 4, 115���170% wider than antenna 1 peduncle article 2 (or rarely equal width), setae and setal pattern similar to antenna 1 or setae shorter, occasionally plumose. Gnathopod 2, adult male: 100���220% the length of gnathopod 1, basis usually not especially elongate, propodus elongate and slender or short and broad (rarely similar to gnathopod 1); coxa 1 70���140% the depth of coxa 2; basis concave or straight; ischium anteriorly rounded or straight; propodus variably shaped, slender or broad (posterior length 120���290% of central width), palm only on the distal portion of the propodus or nearly the full length of the propodus, without a bulge or tooth defining it proximally at the junction of the carpus, palm variously toothed; dactyl 33���75% the length of the propodus. Gnathopod 2, juvenile male: shorter than the adult male gnathopod 2, palm bearing 1���2 strong spines about midway along the length of the propodus, dactyl ending at the spines. Gnathopod 2, female: only slightly larger than gnathopod 1, palm of the propodus convex or concave. Pereopods 3 and 4: propodus, posterior margin bearing setae but not spines; c oxa 4, posterior margin straight to shallowly concave. Pereopod 5, male: similar to but shorter than pereopods 6 and 7 or basis posteriorly concave; merus not differing. Uropod 1: peduncle with short ventrodistal spinous process underlying the rami, length ~25���50% of the outer ramus length. Uropod 3: peduncle bearing 0���2 rows of spines dorsally, ending in a corona of spines at the distal margin (rarely a single seta or single spine); rami with 0���1 spines (outer), 0���4 spines (inner), outer ramus subequal to a third shorter than the inner and bearing 0���9 cusps, occasionally with 1���2 apical spines that are straight or dorsally recurved. Component species. Ischyrocerus anguipes Kr��yer, 1838 (N. Europe and Arctic Ocean); I. latipes Kr��yer, 1842 (Arctic Ocean); I. minutus Liljeborg, 1851 (N. Europe); I. megacheir (Boeck, 1871) (40��N��� 80��N, Atlantic to Arctic Ocean); I. brevicornis (Sars, 1879) (E. Greenland, Arctic Ocean); I. tuberculatus (Hoek, 1882) (Barents Sea, 71��N��� 77��N); I. tenuicornis (Sars, 1885) (N. Europe); I. nanoides (Hansen, 1887) (Arctic, Baffin Bay and W Greenland, 61��N ��� 81��N); I. megalops Sars, 1894 (N. Europe); I. commensalis Chevreux, 1900 (E. Atlantic Canada and Saguenay Fjord); I. brusilovi Gurjanova, 1933 (Russian waters); I. enigmaticus Gurjanova, 1934 (Kara Sea, 78��58��N); I. cristatus Gurjanova, 1938 (Sea of Japan); I. elongatus Gurjanova, 1938 (Sea of Japan); I. rhodomelae Gurjanova, 1938 (Sea of Japan); I. serratus Gurjanova, 1938 (Sea of Japan); I. hanseni Stephensen, 1944 (64��N, between Iceland and Greenland); I. albanovi Gurjanova, 1946 (Arctic Ocean); I. laptevi Gurjanova, 1946 (Arctic Ocean); I. chamissoi Gurjanova, 1951 (Russian waters); I. dezhnevi Gurjanova, 1951 (Russian waters); I. krascheninnikovi Gurjanova, 1951 (Russian waters); I. stephenseni Gurjanova, 1951 (Russian waters); I. pelagops J.L. Barnard, 1962 (California); I. hortator J.L. Barnard, 1964 (off Chile); I. malacus J.L. Barnard, 1964 (California); I. gurjanovae Kudrjaschov, 1975 (Kurile Islands); I. tzvetkovae Kudrjaschov, 1975 (Kurile Islands); I. fractus King & Holmes, 2004 (Ireland). Remarks. Species were retained in Ischyrocerus if they lacked the key characters noted above for Neoischyrocerus in the appearance of the male gnathopod 2, pereopod dactyls or uropod 3 spination pattern. Ischyrocerus fractus is the only species known in this genus where the male���s gnathopod 2 propodus is very little different from the female���s. It is also the smallest known at adulthood for this genus (2 mm). Excluded, but uncertain generic status. Ischyrocerus camptonyx Thurston, 1974b from subantarctic Signy Island is not Ischyrocerus. It is possibly an undescribed species of Jassa or synonymous with J. alonsoae, in which case Thurston���s name would take precedence. Jassa thurstoni Conlan, 1990 (called J. falcata form 2 by Thurston) and Pleojassa moorei n. sp. (called J. falcata form 3) are also known from Thurston���s collections there. For I. camptonyx, hallmarks of the genus Jassa, rather than Ischyrocerus are the spines at the tip of the antenna 2, the sinuous palmed gnathopod 2, the strong overlap of the merus over the carpus on pereopods 3 and 4, the typical Jassa -like uropod 3 with long peduncle lacking mid-dorsal spines (but with a corona of spines around the distal margin), a lateral setal brush and the strong hooked spines at the tip of the outer ramus, and the telson with a long seta at each corner rather than a spine. However, Thurston describes the uropod outer ramus ���with three stout hooked spines dorsally near apex and a minute comb with five-six teeth laterally���, which does not correspond to his illustration and are not Jassa -like. Possibly, though, his description could be interpreted differently. One of the three spines may be the apically immersed, dorsally recurved spine typical of Jassa, the other two spines are cusps, and the five���six teeth are minute dorsal cusps proximal to the two large ones. If so, then this also speaks of I. camptonyx as being a Jassa, either its own species or synonymous with J. alonsoae. It is not a Pleojassa, even though the male���s second-gnathopod resembles that of P. moorei, because this genus lacks a gill on gnathopod 2 while I. camptonyx possesses one. Thurston considered that the few males available for study were juvenile because they all lacked a thumb as in Jassa. However, some of these specimens were larger than the adult, ovigerous females. The female allotype was 4.5 mm and the male holotype was 5.5 mm. This suggests that the male holotype is actually an adult that will not produce a thumb, in which case it is not Jassa. Therefore, until the range of variation can be assessed in Thurston���s specimens, this species should remain in Ischyrocerus with a question as to its proper generic placement. Uncertain status of, Published as part of Conlan, Kathleen E., 2021, New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini, pp. 1-72 in Zootaxa 4921 (1) on pages 57-61, DOI: 10.11646/zootaxa.4921.1.1, http://zenodo.org/record/4496015, {"references":["Kroyer, H. (1838) Gronlands amfipoder beskrevne af Henrick Kroyer. Det Kongelige Danske Videnskabernes Selskabs Naturvidenskabelige og Mathematiske Afhandlinger, 7, 229 - 326. https: // doi. org / 10.5962 / bhl. title. 13747","Just, J. (2017) A fresh look at the higher classification of the Siphonoecetini Just, 1983 (Crustacea, Amphipoda, Ischyroceridae) 12: with a key to all taxa. Zootaxa, 4320 (2), 321 - 338. https: // doi. org / 10.11646 / zootaxa. 4320.2.7","Leach, W. E. (1814) Crustaceology. 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Abteilung fur Systematik, Okologie und Geographie der Tiere, 34, 633 - 659. https: // doi. org / 10.5962 / bhl. part. 19898","Barnard, K. H. (1940) Contributions to the crustacean fauna of South Africa. 12. Further additions to the Tanaidacea, Isopoda and Amphipoda, together with keys for the identification of hitherto recorded marine and fresh-water species. Annals of the South African Museum, 32, 381 - 543.","Schellenberg A. (1953) Erganzungen zur Amphipodenfauna Sudwest-Afrikas nebst Bemerkungen uber Brutraumbildung. Mitteilungen aus dem Museum f ʾ r Naturkunde in Berlin. Zoologisches Museum und Institut f ʾ r Spezielle (Berlin), 29 (1), 107 - 126. https: // doi. org / 10.1002 / mmnz. 19530290105","Ledoyer, M. (1979) Les gammariens de la pente externe du Grand Recif de Tulear (Madagascar) (Crustacea Amphipoda). Memoir Del Museo Civico Di Storia Naturale Di Verona, IIa Serie, Sezione Scienze Della Vita, 2, 1 - 149.","Barnard, J. L. (1964) Some bathyal Pacific Amphipoda collected by the USS Albatross. Pacific Science, 18, 315 - 335.","Kroyer, H. (1842) Nye nordiske slaegter og arter af amfipodernes orden, henhorende til familien Gammarina. (Forelobigt uddrag af et storre arbejde). Naturhistorisk Tidsskrift, 4, 141 - 166.","Liljeborg, W. (1851) Bidrag till Norra Rysslands och Norriges fauna, samlade under en vetenskaplig resa i dessa lander 1848. Kongliga Svenska vetenskaps-akademiens handlingar, 1850, 233 - 341.","Boeck A. (1871) Bidrag til Californiens amphipodefauna. Forhandlinger i Videnskabs-Selskabet i Christiana, 1871, 32 - 51.","Sars, G. O. (1879) Crustacea et Pycnogonida nova in itinere 2 do et 3 tio expeditionis Norvegicae anno 1877 & 78 collecta (prodromus descriptionis). Archiv for Mathematik og Naturvidenskab. 4, 427 - 476.","Hoek P. P. C. (1882) Die Crustaceen gesammelt waehrend der Fahrten des \" Willem Barents \" in den Jahren 1878 und 1879. Niederlandisches Archiv f ʾ r Zoologie, Supplementbind, 1 (7), 1 - 75.","Sars, G. O. (1885) Den Norske Nordhavs-expedition, 1876 - 1878. Zoologi, Crustacea I, Bind 6, 1 - 276.","Hansen H. J. (1887) Malacostraca marine Groenlandiae occidentalis. Oversigt over det vestlige Gronlands fauna of malakostrake havkrebsdyr Videnskabelige. Meddelelser fra Dansk Naturhistorisk Forening I Kobenhavn, 4 (9), 5 - 217. https: // doi. org / 10.5962 / bhl. title. 16332","Sars, G. O. (1894) Amphipoda. Part XXVII & XXVIII. Podoceridae (concluded), Corophiidae, Cheluridae. An account of the Crustacea of Norway, with short descriptions and figures of all the species, 1, 589 - 628. https: // doi. org / 10.5962 / bhl. title. 1164","Chevreux, E. (1900) Amphipodes provenant des campagnes de \" l'Hirondelle \" 1885 - 1888. Resultats des campagnes scientifiques du Prince Albert I de Monaco, 16, 1 - 195.","Gurjanova, E. (1933) Zur Amphipoden fauna des Karischen Meeres. Zoologischer Anzeiger, 103 (5 - 6), 119 - 128.","Gurjanova, E. (1934) Neue formen von Amphipoden des Karischen Meeres. Zoologischer Anzeiger, 108, 122 - 130.","Gurjanova, E. (1938) Amphipoda, Gammaroidea zalikov Siaukhu i Sudzukhe (Yaponskoe More). [Amphipoda, Gammaroidea of Siaukhu Bay and Sudzukhe Bay (Japan Sea)]. Reports of the Japan Sea Hydrobiological Expedition of the Zoological Institute of the Academy of Sciences USSR in 1934, 1, 241 - 404,","Gurjanova, E. (1946) New species of Isopoda and Amphipoda from the Arctic Ocean. Compendium of results, Drifting Expedition, Icebreaker \" Cedov \", 1937 - 1940, Moscow, 3, 272 - 297.","King, R. A. & Holmes, J. M. C. (2004) A new species of Ischyrocerus (Crustacea: Amphipoda) from Ireland, with a review of Ischyrocerus anguipes and Ischyrocerus minutus from the North-East Atlantic. Journal of Natural History, 38 (14), 1757 - 1772. https: // doi. org / 10.1080 / 0022293031000156358","Thurston, M. H. (1974 b) The Crustacea Amphipoda of Signy Island, South Orkney Islands. British Antarctic Survey Scientific Reports, 71, 1 - 133.","Conlan, K. E. (1990) Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031 - 2075. https: // doi. org / 10.1139 / z 90 - 288","Walker, A. O. (1904) Report on the Amphipoda collected by Professor Herdman, at Ceylon, in 1902. In: Report to the Government of Ceylon on the Pearl Oyster Fisheries of the Gulf of Manaar, with supplementary reports upon the marine biology of Ceylon. Part II. The Royal Society, London, pp. 229 - 300.","Chilton, C. (1921) Some New Zealand Amphipoda. 2. Transactions and Proceedings of the New Zealand Institute, 53, 220 - 234."]}

Genus Plumulojassa n. gen. Description of male. Maximum body length 4.1 mm. Head lobe: triangular, apically acute. Antenna 1: accessory flagellum 1 article. Antenna 2: slightly stouter than antenna 1 but hardly longer, filter setae somewhat shorter, never with plumose setae; flagellum with at least the last two articles bearing posteriorly curved spines, first article considerably longer than any of the following articles. Maxilla 1: inner plate bearing a few short, fine setae; palp without setae at the base of article 1, article 2 with 1 row of facial setae. Gnathopod 1: coxa rectangular; propodus defined by 3 spines (medial-lateral-medial), these mid-distant along the palm; dactyl not facially striated. Gnathopod 2: with a gill; coxa deeper posteriorly; basis, anterolateral and anteromedial margins clothed in long plumose setae; carpus less than 1/4 propodus length; propodus, palm with a broad, bifid or trifid hinge tooth, defined by two narrow, apically acute teeth, these reaching nearly to the depth of the hinge tooth, thus giving the palm a transverse appearance; dactyl shorter than the propodus, inner margin slightly sinuous, tip reaching beyond the posterior defining tooth; dactyl, cusps reduced to small buttons interspersed with a few short setae. Pereopod 3: coxa deepest at the centre; basis not slenderer in larger males, margins convex; merus overlapping the carpus, anterior margin bearing a series of single plumose setae; propodus not posteriorly spinose. Pereopods 5–7: at least one basis posterodistally produced, anterior margin with a few short setae and no spines; merus not posteriorly spinose; carpus bearing 2 spines at the posterodistal angle on pereopod 5 and sometimes also on pereopod 6; spines lacking on pereopod 7; propodus not markedly expanded anteriorly; dactyl without facial striations, posterior (outer) margin not cusped distally, anterior (inner) margin bearing a seta only at the unguis. Pleopods: rami long, length> depth of the pleon, each with 2 coupling hooks. Urosome: segment 1 bearing a pair of setae dorsally. Uropod 3: peduncle mid-ventrally setose, without mid-dorsal spines or mid-ventral setae, but with a crown of spines dorsomedially at the insertion of the rami, and a small cluster of setae distolaterally; outer ramus not setose mid-dorsally, tipped by a basally immersed, dorsally recurved spine, a single seta at the spine’s point of immersion and a dorsal cluster of minute cusps proximal to the spine, none of these cusps particularly larger than the other; inner ramus with a single apical spine. Telson: dorsolateral cusps accompanied by setae (1 long, single and 2 short, plumose) but without spines. Description of adult female. Body length at maturity 2.4–4.0 mm. Character states as in the male except as follows. Brood plates: broad, setae abundant, hook-tipped. Antenna 2: posterior filter setae long, not shorter in larger individuals. Gnathopod 1: basis not flanged, without plumose setae. Gnathopod 2: propodus much larger and different in shape from the propodus of gnathopod 1 but differing only in the following respects from the large male: size slightly smaller, hinge tooth bifid, distal palmar tooth more central, proximal tooth little more than an acute expansion, bearing a large, single medial defining spine; dactyl, inner margin straight, tip apposing the defining spine. Type species. Podocerus ocius Bate, 1862 (monotypy). Etymology. The name refers to the abundant plumose setae on the anterior legs, particularly gnathopod 2, which makes this genus unmistakable among the Jassa -like genera, even at young stages., Published as part of Conlan, Kathleen E., 2021, New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini, pp. 1-72 in Zootaxa 4921 (1) on pages 9-10, DOI: 10.11646/zootaxa.4921.1.1, http://zenodo.org/record/4496015, {"references":["Bate, C. S. (1862) Catalogue of the specimens of Amphipodous Crustacea in the collection of the British Museum. Printed by order of the Trustees, London, 399 pp."]}

Genus Neoischyrocerus n. comb. Supplementary Table S3 Type species. N. claustris J.L. Barnard, 1969 Diagnosis. (with differences from Ischyrocerus in bold). Body length at maturity 1���2 mm (usually), rarely 4���6 mm. Tropical and warm temperate distribution, collected from algae, sponges, corals or from a spiny lobster, 0���16 m, 9��� 40��N and 5��� 34��S. Pereon: dorsally smooth (most species), ridged or carinate (some species). Antenna 1: accessory flagellum 2 articles (second minute), projecting forward or flush with the flagellum; antennae 1 and 2 peduncles subequal in width or antenna 2, 10% wider (based on comparison of antenna 1 peduncle article 2 with antenna 2 peduncle article 4), peduncular setae and setal pattern similar to antenna 1, or slightly shorter, not plumose. Gnathopod 2, adult male: 190���350% the length of gnathopod 1, basis and propodus especially elongate; coxa 1, 60���110% the depth of coxa 2; basis concave or sinuous; ischium anteriorly rounded; propodus often slender (posterior length 180���400% of central width), palm nearly the full length of the propodus, often with a bulge or tooth defining it proximally at the junction of the carpus (sometimes palm continuous with the carpus), sometimes centrally toothed instead and with shallow bulge or teeth at the junction of the dactyl; dactyl half or nearly the full length of the propodus. Gnathopod 2, juvenile male: shorter than the adult male gnathopod 2, palm bearing 1���2 strong spines about midway along the length of the propodus, dactyl ending at the spines. Gnathopod 2, female: only slightly larger than gnathopod 1, palm of the propodus convex (usually) or shallowly concave (rarely). Pereopods 3 and 4: propodus, posterior margin bearing spines or setae; coxa 4, posterior margin straight, not shallowly concave. Pereopod 5, male: similar to but shorter than pereopods 6 and 7 or variously modified with posteriorly concave basis or posteriorly expanded and spinose merus. Uropod 1: peduncle with short ventrodistal spinous process underlying the rami, length ~15���35% of the outer ramus length. Uropod 3: peduncle bearing 1���2 rows of spines dorsally, ending in a single spine at the distal margin, but without a corona of spines around the margin or setae; rami without spines mid-dorsally, outer ramus subequal to or shorter than the inner and bearing 3���8 minute dorsal cusps apically, without (rarely with) a small apical straight spine. Component species (with transferred species in bold). Ischyrocerus longimanus (Haswell, 1879) (Australia); I. parvus Stout, 1913 (California); I. carinatus K.H. Barnard, 1916 (South Africa); I. gorgoniae K.H. Barnard, 1940 (South Africa); I. ctenophorus Schellenberg, 1953 (South Africa); Coxischyrocerus inexpectatus (Ruffo, 1959) (Mediterranean, Red Sea?); N. claustris J.L. Barnard, 1969 (California); N. lilipuna J.L. Barnard, 1970 (Hawaii); I. oahu J.L. Barnard, 1970 (Hawaii); I. oahu oahu J.L. Barnard, 1970 (Hawaii); N. chinipa J.L. Barnard, 1979 (Galapagos Islands and Panama); I. oahu armatus Ledoyer, 1979 (Madagascar); Tropischyrocerus socia (Myers, 1989) (Bora Bora); I. mediodens Myers, 1995 (Papua New Guinea); I. parma Myers, 1995 (Papua New Guinea); I. apiensis Myers, 1997 (Samoa); N. vidali Ortiz & Lalana, 2002 (Cuba); C. rhombocoxus Just, 2009 (Australia); T. pugilus Just, 2009 (Australia). Remarks. Species of Ischyrocerus were transferred to Neoischyrocerus if they demonstrated at least one key character (grossly enlarged and pendulous male gnathopod 2 similar in shape to that of others in the genus; dactyls with comb-like striae as noted in J.L. Barnard (1970), Conlan (1995) and Ortiz & Lalana (2002); similar spination on uropod 3). Presence or absence of these striae were not mentioned by other authors, therefore questioning as to whether this character had been looked for. Mouthpart characteristics were not widely described, but may be useful for generic definition, especially the clavate vs slenderer shape of the mandibular palp and the presence/absence of a long apical seta on the maxilla 1 inner plate. Excluded but uncertain generic status. Ischyrocerus kapu J.L. Barnard, 1970 from Hawaii. The author based the generic assignment on a single male specimen. He noted its resemblance to N. lilipuna but also considered that it should be in a new genus. On balance, though, he assigned it to Ischyrocerus but noted that this was based on limited information because the specimen lacked antennae and pereopods and the female was also unknown. The male���s gnathopod 2 is unusual in having a long conical extension of the merus underneath the propodus, a feature that is not known for either Ischyrocerus or Neoischyrocerus. Myers (1995) stated that I. kapu is congeneric with other species being transferred to Neoischyrocerus. The male���s propodus is wider than in other members of Neoischyrocerus, but its uropod 3 resembles other species of Neoischyrocerus rather than Ischyrocerus. Further material demonstrating the species��� complete morphology is required before it can be confidently transferred to Neoischyrocerus or to a new genus. Genus Ischyrocerus n. comb. Supplementary Table S4 Type species. Ischyrocerus anguipes Kr��yer, 1838 Diagnosis (with differences from Neoischyrocerus in bold). Body length at maturity 2���18 mm, though most species are> 5 mm long at adulthood. Primarily known from the Northern Hemisphere in cold temperate to polar waters from 32��N (La Jolla, California; J.L. Barnard 1969) to 81��N in the Arctic Ocean (Stephensen 1944), collected from algae, hydroids, crabs or substrate unknown, 1 to ~ 2000 m. Widely known in Europe but not in the Southern Hemisphere, although one species was found at 42��S off of Chile (J.L. Barnard 1964). Pereon: dorsally smooth (most species), ridged or carinate (some species). Antenna 1: accessory flagellum 2 articles (second minute), flush with the flagellum or rarely projecting forward; antenna 2 peduncle article 4, 115���170% wider than antenna 1 peduncle article 2 (or rarely equal width), setae and setal pattern similar to antenna 1 or setae shorter, occasionally plumose. Gnathopod 2, adult male: 100���220% the length of gnathopod 1, basis usually not especially elongate, propodus elongate and slender or short and broad (rarely similar to gnathopod 1); coxa 1 70���140% the depth of coxa 2; basis concave or straight; ischium anteriorly rounded or straight; propodus variably shaped, slender or broad (posterior length 120���290% of central width), palm only on the distal portion of the propodus or nearly the full length of the propodus, without a bulge or tooth defining it proximally at the junction of the carpus, palm variously toothed; dactyl 33���75% the length of the propodus. Gnathopod 2, juvenile male: shorter than the adult male gnathopod 2, palm bearing 1���2 strong spines about midway along the length of the propodus, dactyl ending at the spines. Gnathopod 2, female: only slightly larger than gnathopod 1, palm of the propodus convex or concave. Pereopods 3 and 4: propodus, posterior margin bearing setae but not spines; c oxa 4, posterior margin straight to shallowly concave. Pereopod 5, male: similar to but shorter than pereopods 6 and 7 or basis posteriorly concave; merus not differing. Uropod 1: peduncle with short ventrodistal spinous process underlying the rami, length ~25���50% of the outer ramus length. Uropod 3: peduncle bearing 0���2 rows of spines dorsally, ending in a corona of spines at the distal margin (rarely a single seta or single spine); rami with 0���1 spines (outer), 0���4 spines (inner), outer ramus subequal to a third shorter than the inner and bearing 0���9 cusps, occasionally with 1���2 apical spines that are straight or dorsally recurved. Component species. Ischyrocerus anguipes Kr��yer, 1838 (N. Europe and Arctic Ocean); I. latipes Kr��yer, 1842 (Arctic Ocean); I. minutus Liljeborg, 1851 (N. Europe); I. megacheir (Boeck, 1871) (40��N��� 80��N, Atlantic to Arctic Ocean); I. brevicornis (Sars, 1879) (E. Greenland, Arctic Ocean); I. tuberculatus (Hoek, 1882) (Barents Sea, 71��N��� 77��N); I. tenuicornis (Sars, 1885) (N. Europe); I. nanoides (Hansen, 1887) (Arctic, Baffin Bay and W Greenland, 61��N ��� 81��N); I. megalops Sars, 1894 (N. Europe); I. commensalis Chevreux, 1900 (E. Atlantic Canada and Saguenay Fjord); I. brusilovi Gurjanova, 1933 (Russian waters); I. enigmaticus Gurjanova, 1934 (Kara Sea, 78��58��N); I. cristatus Gurjanova, 1938 (Sea of Japan); I. elongatus Gurjanova, 1938 (Sea of Japan); I. rhodomelae Gurjanova, 1938 (Sea of Japan); I. serratus Gurjanova, 1938 (Sea of Japan); I. hanseni Stephensen, 1944 (64��N, between Iceland and Greenland); I. albanovi Gurjanova, 1946 (Arctic Ocean); I. laptevi Gurjanova, 1946 (Arctic Ocean); I. chamissoi Gurjanova, 1951 (Russian waters); I. dezhnevi Gurjanova, 1951 (Russian waters); I. krascheninnikovi Gurjanova, 1951 (Russian waters); I. stephenseni Gurjanova, 1951 (Russian waters); I. pelagops J.L. Barnard, 1962 (California); I. hortator J.L. Barnard, 1964 (off Chile); I. malacus J.L. Barnard, 1964 (California); I. gurjanovae Kudrjaschov, 1975 (Kurile Islands); I. tzvetkovae Kudrjaschov, 1975 (Kurile Islands); I. fractus King & Holmes, 2004 (Ireland). Remarks. Species were retained in Ischyrocerus if they lacked the key characters noted above for Neoischyrocerus in the appearance of the male gnathopod 2, pereopod dactyls or uropod 3 spination pattern. Ischyrocerus fractus is the only species known in this genus where the male���s gnathopod 2 propodus is very little different from the female���s. It is also the smallest known at adulthood for this genus (2 mm). Excluded, but uncertain generic status. Ischyrocerus camptonyx Thurston, 1974b from subantarctic Signy Island is not Ischyrocerus. It is possibly an undescribed species of Jassa or synonymous with J. alonsoae, in which case Thurston���s name would take precedence. Jassa thurstoni Conlan, 1990 (called J. falcata form 2 by Thurston) and Pleojassa moorei n. sp. (called J. falcata form 3) are also known from Thurston���s collections there. For I. camptonyx, hallmarks of the genus Jassa, rather than Ischyrocerus are the spines at the tip of the antenna 2, the sinuous palmed gnathopod 2, the strong overlap of the merus over the carpus on pereopods 3 and 4, the typical Jassa -like uropod 3 with long peduncle lacking mid-dorsal spines (but with a corona of spines around the distal margin), a lateral setal brush and the strong hooked spines at the tip of the outer ramus, and the telson with a long seta at each corner rather than a spine. However, Thurston describes the uropod outer ramus ���with three stout hooked spines dorsally near apex and a minute comb with five-six teeth laterally���, which does not correspond to his illustration and are not Jassa -like. Possibly, though, his description could be interpreted differently. One of the three spines may be the apically immersed, dorsally recurved spine typical of Jassa, the other two spines are cusps, and the five���six teeth are minute dorsal cusps proximal to the two large ones. If so, then this also speaks of I. camptonyx as being a Jassa, either its own species or synonymous with J. alonsoae. It is not a Pleojassa, even though the male���s second-gnathopod resembles that of P. moorei, because this genus lacks a gill on gnathopod 2 while I. camptonyx possesses one. Thurston considered that the few males available for study were juvenile because they all lacked a thumb as in Jassa. However, some of these specimens were larger than the adult, ovigerous females. The female allotype was 4.5 mm and the male holotype was 5.5 mm. This suggests that the male holotype is actually an adult that will not produce a thumb, in which case it is not Jassa. Therefore, until the range of variation can be assessed in Thurston���s specimens, this species should remain in Ischyrocerus with a question as to its proper generic placement. Uncertain status of Ischyrocerus anguipes in the Southern Hemisphere. Sars��� (1894) excellent illustrations of I. anguipes may have resulted in some mis-identifications by early workers in the Southern Hemisphere. Alternatively, their identifications were correct and I. anguipes was being introduced by shipping if the specimens came from ports. K.H. Barnard���s (1916) ��� I. anguipes ��� could have been a species of Neoischyrocerus, however, as the specimens were 3 mm and the male���s second gnathopod propodus was 3.5 x longer than wide with the dactyl nearly the full length of the propodus, which is typical of adult male Neoischyrocerus. Schellenberg���s (1953) ��� I. anguipes ��� from L��deritzbucht, Namibia was a 4.8 mm male which he stated differed from K.H. Barnard���s (1916) ��� I. anguipes ��� in its gnathopod 2 morphology. ���The metacarpus of the 2nd gnathopod is shaped in the same way but stronger and exhibits a spination like on the first gnathopod. The palm is evenly finely corrugated (or: ���wavy���) along its almost entire length.��� (Der fast gleich geformte, aber st��rkere Metacarpus des 2. Gnathopoden zeigt die Bestachelung wie am 1. Gnathopoden. Die Palma ist fast in ihrer ganzen L��nge gleichm��ssig fein gewellt.) (translated from German to English by Jan Beermann, Alfred Wegener Institute, Bremerhaven, Germany). The similarly shaped gnathopods 1 and 2 suggest that this specimen was a female or juvenile, or an adult male of a different species, as adult male I. anguipes have a gnathopod 2 that is more than twice the length of gnathopod 1, with a concave, rather than convex palm. Schellenberg illustrated the uropod 3 outer ramus as 5-cusped, terminating in a basally immersed, dorsally recurved spine similar to Jassa. The corona of spines at the peduncle���s distal margin is typical of Ischyrocerus and Jassa. ��� I. anguipes ��� captured off the coast of Ceylon in ~ 150 m depth were briefly described by Walker (1904) but not illustrated. One male and one ovigerous female were 2.5 mm long. The male���s gnathopod 2 was similar to that of I. anguipes, but this could also be Neoischyrocerus which has similarly shaped, though more pendulous second gnathopods with the dactyl in the largest males nearly the full length of the propodus. Chilton (1921) described ��� I anguipes ��� from Lyttelton, New Zealand which were up to 6 mm long, saying that they closely resembled Sars��� (1894) illustrations of that species. His description was minimal, however, and he provided no illustrations. Genus Ischyrocerus n. comb. Supplementary Table S4 Type species. Ischyrocerus anguipes Kr��yer, 1838 Diagnosis (with differences from Neoischyrocerus in bold). Body length at maturity 2���18 mm, though most species are> 5 mm long at adulthood. Primarily known from the Northern Hemisphere in cold temperate to polar waters from 32��N (La Jolla, California; J.L. Barnard 1969) to 81��N in the Arctic Ocean (Stephensen 1944), collected from algae, hydroids, crabs or substrate unknown, 1 to ~ 2000 m. Widely known in Europe but not in the Southern Hemisphere, although one species was found at 42��S off of Chile (J.L. Barnard 1964). Pereon: dorsally smooth (most species), ridged or carinate (some species). Antenna 1: accessory flagellum 2 articles (second minute), flush with the flagellum or rarely projecting forward; antenna 2 peduncle article 4, 115���170% wider than antenna 1 peduncle article 2 (or rarely equal width), setae and setal pattern similar to antenna 1 or setae shorter, occasionally plumose. Gnathopod 2, adult male: 100���220% the length of gnathopod 1, basis usually not especially elongate, propodus elongate and slender or short and broad (rarely similar to gnathopod 1); coxa 1 70���140% the depth of coxa 2; basis concave or straight; ischium anteriorly rounded or straight; propodus variably shaped, slender or broad (posterior length 120���290% of central width), palm only on the distal portion of the propodus or nearly the full length of the propodus, without a bulge or tooth defining it proximally at the junction of the carpus, palm variously toothed; dactyl 33���75% the length of the propodus. Gnathopod 2, juvenile male: shorter than the adult male gnathopod 2, palm bearing 1���2 strong spines about midway along the length of the propodus, dactyl ending at the spines. Gnathopod 2, female: only slightly larger than gnathopod 1, palm of the propodus convex or concave. Pereopods 3 and 4: propodus, posterior margin bearing setae but not spines; c oxa 4, posterior margin straight to shallowly concave. Pereopod 5, male: similar to but shorter than pereopods 6 and 7 or basis posteriorly concave; merus not differing. Uropod 1: peduncle with short ventrodistal spinous process underlying the rami, length ~25���50% of the outer ramus length. Uropod 3: peduncle bearing 0���2 rows of spines dorsally, ending in a corona of spines at the distal margin (rarely a single seta or single spine); rami with 0���1 spines (outer), 0���4 spines (inner), outer ramus subequal to a third shorter than the inner and bearing 0���9 cusps, occasionally with 1���2 apical spines that are straight or dorsally recurved. Component species. Ischyrocerus anguipes Kr��yer, 1838 (N. Europe and Arctic Ocean); I. latipes Kr��yer, 1842 (Arctic Ocean); I. minutus Liljeborg, 1851 (N. Europe); I. megacheir (Boeck, 1871) (40��N��� 80��N, Published as part of Conlan, Kathleen E., 2021, New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini, pp. 1-72 in Zootaxa 4921 (1) on pages 58-61, DOI: 10.11646/zootaxa.4921.1.1, http://zenodo.org/record/4496015, {"references":["Barnard, J. L. (1969) Gammaridean Amphipoda of the rocky intertidal of California: Monterey Bay to La Jolla. Bulletin of the United States National Museum, 258, 1 - 230. https: // doi. org / 10.5479 / si. 03629236.258.1","Haswell, W. A. (1879) On some additional new genera and species of amphipodous crustaceans. Proceedings of the Linnean Society of New South Wales, 4, 319 - 350. https: // doi. org / 10.5962 / bhl. part. 22854","Stout, V. R. (1913) Studies in Laguna Amphipoda. Zoologische Jahrbucher. Abteilung fur Systematik, Okologie und Geographie der Tiere, 34, 633 - 659. https: // doi. org / 10.5962 / bhl. part. 19898","Barnard, K. H. (1916) Contributions to the crustacean fauna of South Africa. 5. The Amphipoda. Annals of the South African Museum, 15 (3), 105 - 302. https: // doi. org / 10.5962 / bhl. title. 10646","Barnard, K. H. (1940) Contributions to the crustacean fauna of South Africa. 12. Further additions to the Tanaidacea, Isopoda and Amphipoda, together with keys for the identification of hitherto recorded marine and fresh-water species. Annals of the South African Museum, 32, 381 - 543.","Schellenberg A. (1953) Erganzungen zur Amphipodenfauna Sudwest-Afrikas nebst Bemerkungen uber Brutraumbildung. Mitteilungen aus dem Museum f ʾ r Naturkunde in Berlin. Zoologisches Museum und Institut f ʾ r Spezielle (Berlin), 29 (1), 107 - 126. https: // doi. org / 10.1002 / mmnz. 19530290105","Ruffo, S. (1959) Contributo alla conoscenza degli anfipodi delle grotte sottomarine. Pubblicazioni della Stazione Zoologica di Napoli, 30 (Supplemento), 402 - 416","Barnard, J. L. 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