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We describe a new species of Stenasellus Dollfus, 1897 (Isopoda: Asellota: Stenasellidae) from stagnant freshwater habitats in a cave on Socotra Island, Yemen. S. taitii n. sp. is the first endemic stenasellid found in Socotra, showing relatively closer morphological affinities to species from the Middle East (Oman, Iran) than from the African mainland, corresponding to the known paleogeographical connection of the archipelago to Southern Arabia. With notes on the protection of Socotran groundwaters.

Stenasellus taitii n. sp. Messana & Argano Holotype male MZUF 5038, Yemen, Socotra Archipelago, Socotra Island, Erher Cave, 12��33���02.7���N, 54��27���35.7���E, alt. 250 msl., K. Van Damme leg., 27 December 2003. Paratypes: 8 males (one slide of pleopods 1 & 2), 8 females, 1 indet., MZUF 5039, same locality and date as holotype; 2 males (one on 4 slides), 8 females (one on 4 slides), MZUF 5040, Yemen, Socotra Archipelago, Socotra Island, stagnant pools near the entrance of Erher Cave, NE Socotra, K. Van Damme & S. Taiti leg, 16 January 2003. Maximum observed length of females 13.7 mm, maximum observed length of males 12.2 mm. Etymology. The new species is named after our esteemed colleague Dr Stefano Taiti who collected the new species together with Kay Van Damme and for his excellent studies on the Isopoda of Socotra (Taiti & Ferrara 2004; Taiti & Checcucci 2009). Diagnosis. A pink/reddish (in life) Stenasellus (13.7 mm maximum observed length), anterior corner of cephalon with typical black spot of Bellonci Organ. Antennae long reaching pereonite 7 (Figs 1a, 2a, b). Lateral and middle endites of maxilla bearing respectively 7 and 9 curved dentate setae; mesial margin of maxilliped endite with three coupling hooks. Protopod of first male pleopod with two small strong dentate coupling hooks. Appendix masculina slender, elongated, with tiny distal spine (Fig. 2c); endopod of pleopods III���V distally biphid. Uropods (Figs 1a, 5g) as long as pleotelson. Description (based on paratypes). Antennulae (Fig. 3h) short, reaching posterior margin of first pereonite, peduncle with four articles, first one with seven strong setae on distal margin, second one bearing four plumose and four simple setae on the same position, third article bearing one plumose seta and three distal glabrous setae, fourth article with two plumose setae. Two aesthetascs are present on distal corner of each of last four segments of flagellum. Peduncle of antennae (Fig. 3i) six-segmented, third article with typical antennal scale (Fig. 3g) with two strong setae on lateral margin, one and five plumose seta are present on distal caudal corner of respectively fifth and sixth article. Maxillula (Fig. 3a) outer lobe with a dozen spinate setae and four glabrous setae ventral on inner corner; inner lobe with three robust setae (innermost one serrate and others spinulate) and two ventral, thin and glabrous setae. Maxilla (Fig. 3b) with ten spinulate falciform setae on two rows on inner lobe, and seven spinulate setae on each of the other lobes. Maxilliped (Fig. 3c) with three toothed coupling hooks, ten simple setae on dorsal side and nine spinulate and one glabrous terminal setae on endite, palp bearing one spinulate seta on distal outer corner of second article and one glabrous on penultimate article. Left mandible (Figs 3d, 2d) with incisor process three-toothed and sclerotized lama, lacinia mobilis strong, four-toothed with 3 small teeth on lateral margin, eight to ten denticulate and one to three glabrous lifting spines. Molar process with almost 16���25 long setae. Right mandible (Figs 3f, 2e) with incisor process three-toothed and sclerotized lama, lacinia mobilis three toothed, thinner than in left mandible, three to seven denticulate and 9���12 glabrous lifting spines. Molar process with up to 16 long setae. Mandibular palp (Fig. 3e) triarticulate, first article with one long seta on distal corner and smaller one subdistal, second article with 16���20 setae on internal margin and terminal article with almost 20���25 setae on two rows, two distal ones longer than the others. Pereopod I haptorial (Fig. 4a). Dactylus with 8���15 teeth on sternal margin, propodus with 10���25 pectinate strong spines and several long setae. Pereopods II���VII (Fig. 4 b���g) progressively increasing, dactylus with distal accessory spine on sternal margin, propodus and carpus with single plumose seta on distal tergal corner, basis with five to seven plumose setae, carpus of pereopods 2���4 bear also bipectinate seta in same position. Pleopod I male (Fig. 5b) with two strong toothed coupling hooks on inner margin of protopod. Protopod two times longer than wide, endopod twisted as in S. vermeuleni Magniez & Stock, 2000, with several plumose setae on inner margin and several short distal naked ones. Pleopod II male (Fig. 5c) protopod external margin convex, with one paramedial spine; proximal article of exopod short with one short seta on external margin, second article suboval and externally twisted with about twenty plumose setae on margin; endopod second article longer than first one, distal article slender gutter-like and fluteshaped in its caudal part, bearing small external distal spine (Fig. 3) and several tiny setae. Pleopod II female (Fig. 5a) subquadrangular, with four spines on sternal face and dozen of long marginal plumose setae. Pleopods III���V (Fig. 5 d���f) endopod distally bifid, exopod divided by a transverse suture. Distal margin of pleopod 3 with few naked setae, in pleopod 4 these are more numerous, plumose, distal and internal. Fifth pleopod without setae. Uropods (Fig. 5g) as long as pleotelson, protopod about three times longer than wide, endopod subequal to exopod and bearing long distal glabrous setae, exopod about two times longer than protopod, with four plumose setae, two paradistal and two subdistal. Remarks. The stenasellids were so far collected in Erher Cave, in the stagnant pools created by the overflow of the waterfall and in the freshwater lake at the far end. They were often hiding inside the crevices of the limestone formations and always together with the endemic blind cave shrimp Halocaridinides socotraensis (Decapoda: Atyidae). Other, smaller Asellota have been found in Fozzreher Cave (Van Damme, pers. obs.) in the West of Socotra (Fransen & Van Damme 2018). Unfortunately the specimens collected were lost and could not be examined. Details on water management and chemistry of the locality are given in Fransen and Van Damme (2018)., Published as part of Messana, Giuseppe, Damme, Kay Van & Argano, Roberto, 2019, A new stygobiotic Stenasellus Dollfus, 1897 (Asellota: Stenasellidae) from Socotra Island, Yemen, pp. 552-562 in Zootaxa 4683 (4) on pages 553-559, DOI: 10.11646/zootaxa.4683.4.5, http://zenodo.org/record/3479597, {"references":["Taiti, S. & Ferrara, F. (2004) The terrestrial Isopoda (Crustacea: Oniscidae) of the Socotra Archipelago. Fauna of Arabia, 20, 211 - 325.","Taiti, S. & Checcucci, I. (2009) New species and records of terrestrial Isopoda (Crustacea, Oniscidae) from Socotra Island, Yemen. Zookeys, 31, 73 - 103. https: // doi. org / 10.3897 / zookeys. 31.140","Magniez, G. J., Stock J. H. (2000) Les Stenasellidae (Crustacea Isopoda Asellota Anophtalmes) des eaux souterraines du Sultanat d'Oman. Bulletin Zoological Museum University of Amsterdam, 50 (9), 163 - 184.","Fransen, C. H. J. M. & Van Damme, K. (2018) A new stygobiont species of Halocaridinides Fujino & Shokita, 1975 (Crustacea, Decapoda, Caridea, Atyidae) from caves on Socotra Island (Yemen), with notes on the genus. Zootaxa, 4442 (2), 241 - 261. https: // doi. org / 10.11646 / zootaxa. 4442.2.3"]}

Stenasellus taitii n. sp. Messana & Argano Holotype male MZUF 5038, Yemen, Socotra Archipelago, Socotra Island, Erher Cave, 12°33’02.7”N, 54°27’35.7”E, alt. 250 msl., K. Van Damme leg., 27 December 2003. Paratypes: 8 males (one slide of pleopods 1 & 2), 8 females, 1 indet., MZUF 5039, same locality and date as holotype; 2 males (one on 4 slides), 8 females (one on 4 slides), MZUF 5040, Yemen, Socotra Archipelago, Socotra Island, stagnant pools near the entrance of Erher Cave, NE Socotra, K. Van Damme & S. Taiti leg, 16 January 2003. Maximum observed length of females 13.7 mm, maximum observed length of males 12.2 mm. Etymology. The new species is named after our esteemed colleague Dr Stefano Taiti who collected the new species together with Kay Van Damme and for his excellent studies on the Isopoda of Socotra (Taiti & Ferrara 2004; Taiti & Checcucci 2009). Diagnosis. A pink/reddish (in life) Stenasellus (13.7 mm maximum observed length), anterior corner of cephalon with typical black spot of Bellonci Organ. Antennae long reaching pereonite 7 (Figs 1a, 2a, b). Lateral and middle endites of maxilla bearing respectively 7 and 9 curved dentate setae; mesial margin of maxilliped endite with three coupling hooks. Protopod of first male pleopod with two small strong dentate coupling hooks. Appendix masculina slender, elongated, with tiny distal spine (Fig. 2c); endopod of pleopods III–V distally biphid. Uropods (Figs 1a, 5g) as long as pleotelson. Description (based on paratypes). Antennulae (Fig. 3h) short, reaching posterior margin of first pereonite, peduncle with four articles, first one with seven strong setae on distal margin, second one bearing four plumose and four simple setae on the same position, third article bearing one plumose seta and three distal glabrous setae, fourth article with two plumose setae. Two aesthetascs are present on distal corner of each of last four segments of flagellum. Peduncle of antennae (Fig. 3i) six-segmented, third article with typical antennal scale (Fig. 3g) with two strong setae on lateral margin, one and five plumose seta are present on distal caudal corner of respectively fifth and sixth article. Maxillula (Fig. 3a) outer lobe with a dozen spinate setae and four glabrous setae ventral on inner corner; inner lobe with three robust setae (innermost one serrate and others spinulate) and two ventral, thin and glabrous setae. Maxilla (Fig. 3b) with ten spinulate falciform setae on two rows on inner lobe, and seven spinulate setae on each of the other lobes. Maxilliped (Fig. 3c) with three toothed coupling hooks, ten simple setae on dorsal side and nine spinulate and one glabrous terminal setae on endite, palp bearing one spinulate seta on distal outer corner of second article and one glabrous on penultimate article. Left mandible (Figs 3d, 2d) with incisor process three-toothed and sclerotized lama, lacinia mobilis strong, four-toothed with 3 small teeth on lateral margin, eight to ten denticulate and one to three glabrous lifting spines. Molar process with almost 16–25 long setae. Right mandible (Figs 3f, 2e) with incisor process three-toothed and sclerotized lama, lacinia mobilis three toothed, thinner than in left mandible, three to seven denticulate and 9–12 glabrous lifting spines. Molar process with up to 16 long setae. Mandibular palp (Fig. 3e) triarticulate, first article with one long seta on distal corner and smaller one subdistal, second article with 16–20 setae on internal margin and terminal article with almost 20–25 setae on two rows, two distal ones longer than the others. Pereopod I haptorial (Fig. 4a). Dactylus with 8–15 teeth on sternal margin, propodus with 10–25 pectinate strong spines and several long setae. Pereopods II–VII (Fig. 4 b–g) progressively increasing, dactylus with distal accessory spine on sternal margin, propodus and carpus with single plumose seta on distal tergal corner, basis with five to seven plumose setae, carpus of pereopods 2–4 bear also bipectinate seta in same position. Pleopod I male (Fig. 5b) with two strong toothed coupling hooks on inner margin of protopod. Protopod two times longer than wide, endopod twisted as in S. vermeuleni Magniez & Stock, 2000, with several plumose setae on inner margin and several short distal naked ones. Pleopod II male (Fig. 5c) protopod external margin convex, with one paramedial spine; proximal article of exopod short with one short seta on external margin, second article suboval and externally twisted with about twenty plumose setae on margin; endopod second article longer than first one, distal article slender gutter-like and fluteshaped in its caudal part, bearing small external distal spine (Fig. 3) and several tiny setae. Pleopod II female (Fig. 5a) subquadrangular, with four spines on sternal face and dozen of long marginal plumose setae. Pleopods III–V (Fig. 5 d–f) endopod distally bifid, exopod divided by a transverse suture. Distal margin of pleopod 3 with few naked setae, in pleopod 4 these are more numerous, plumose, distal and internal. Fifth pleopod without setae. Uropods (Fig. 5g) as long as pleotelson, protopod about three times longer than wide, endopod subequal to exopod and bearing long distal glabrous setae, exopod about two times longer than protopod, with four plumose setae, two paradistal and two subdistal. Remarks. The stenasellids were so far collected in Erher Cave, in the stagnant pools created by the overflow of the waterfall and in the freshwater lake at the far end. They were often hiding inside the crevices of the limestone formations and always together with the endemic blind cave shrimp Halocaridinides socotraensis (Decapoda: Atyidae). Other, smaller Asellota have been found in Fozzreher Cave (Van Damme, pers. obs.) in the West of Socotra (Fransen & Van Damme 2018). Unfortunately the specimens collected were lost and could not be examined. Details on water management and chemistry of the locality are given in Fransen and Van Damme (2018).

"A new species of stygobitic isopod from Cerro Colorado Cave, Municipality of Apazapan, near Xalapa, Veracruz, is described. The new species is placed in Mexistenasellus due to the lack of eyes and pigmentation, a head distinct from pereonite 1, and 2 well developed pleonites. Other characters, such as the number of setae in the dactyli of the pereiopods, show slight variations from the original description of the genus. The new species can be distinguished from the previously known 7 species in the genus by the shape of the head, the proportions of the pleotelson and length of uropods. Color in life is pink as is characteristic of the species of Mexistenasellus. A key to the species of Mexistenasellus is provided."

Mexistenasellus floridensis sp. n. is described from Hole in Wall Cave, Jackson County, Florida. The discovery of this unique isopod nearly doubles the range of the Family Stenasellidae in North America, which was previously known from Oaxaca, Mexico to southern Texas, USA. This is the first stenasellid reported swimming in the water column of a cave, a curious finding for an isopod that belongs to a group that is generally more adapted to inhabiting interstitial spaces. Mexistenasellus floridensis occurs syntopically with the subterranean asellid Caecidotea putea. Both species have been observed swimming in the water column, although neither has apparent anatomical adaptations for swimming as compared to the natatory pereopods of Remasellus parvus, an asellid that occurs in caves in Alachua, Madison and Wakulla counties, Florida.

[A new species of the genus Stenasellus (Asellota, Aselloidea) from karstic waters of Sumatra, S. foresti n. sp., belongs to the same phyletic strain as the other Stenasellidae of the continental and insular Far East (Cambodia, Thailand, Phuket Island, Borneo, Sumatra). Its uropods are short and the tip of the copulatory organs shows a very specific structure of the sternal spur and tergal opening. Nouvelle espece de Stenasellus (Asellota, Aselloidea) des eaux karstiques de Sumatra, S. foresti n. sp. appartient au meme groupe evolutif que les autres Stenasellidae de l'Extreme-Orient continental et insulaire (Cambodge, Thailande, Phuket, Borneo, Sumatra). Ses uropodes sont courts et l'extremite des organes copulateurs montre une structure tres specifique de l'eperon sternal et de l'orifice tergal., A new species of the genus Stenasellus (Asellota, Aselloidea) from karstic waters of Sumatra, S. foresti n. sp., belongs to the same phyletic strain as the other Stenasellidae of the continental and insular Far East (Cambodia, Thailand, Phuket Island, Borneo, Sumatra). Its uropods are short and the tip of the copulatory organs shows a very specific structure of the sternal spur and tergal opening. Nouvelle espece de Stenasellus (Asellota, Aselloidea) des eaux karstiques de Sumatra, S. foresti n. sp. appartient au meme groupe evolutif que les autres Stenasellidae de l'Extreme-Orient continental et insulaire (Cambodge, Thailande, Phuket, Borneo, Sumatra). Ses uropodes sont courts et l'extremite des organes copulateurs montre une structure tres specifique de l'eperon sternal et de l'orifice tergal.]

Not applicable

Stenasellus stocki n. sp., a new Stenasellid Isopod from underground waters of Sumatra Island (Indonesia) -Description of a fith species of Stenasellus (Asellota, Aselloidea, Stenasellidae) of Sumatra Island, found in a cave of the Padang region (central part of the island). Relationship of the new taxon with insular and continental species previously know in the Far Eastern area., Description de la cinquième espèce de Stenasellus (Asellota, Aselloidea, Stenasellidae) de Sumatra, provenant d'une grotte de la région de Padang (partie centrale de l'île). Affinités du nouveau taxon avec les espèces insulaires et continentales déjà connues d'Extrême-Orient., J. Magniez Guy. Stenasellus stocki n. sp., nouvel Isopode Stenasellidae des eaux souterraines de Sumatra (Indonésie). In: Bulletin mensuel de la Société linnéenne de Lyon, 70ᵉ année, n°6, juin 2001. pp. 159-164.

The author describes a new species of Stenasellus, collected from a spring on the Kenyan Limestone Outcrop near Vinagoni Village (Kilifi District). S. simonsi n. sp., the third species collected in the country, is similar to the other Kenyan species S. ruffoi Messana 1993, and especially to the Somali species S. pardii Lanza 1966. KEY WORDS: Stenasellidae, Kenya, new species.

The historical discovery and the successive stages in our knowledge of the family Stenasellidae Dudich, 1924, are described. Their morphological features; the diagnosis of the family, and an updated list of its genera with the respective numbers of their taxa and their main characteristics are given. Also, the biogeography and the ecology of the group and relations between burrowing behaviour and general adaptation to life in all types of continental underground waters, are discussed. Next, the putative evolutionary history of the family is presented, taking into account the active dispersal of these isopods and also the role of Quaternary events: the development of aridity in the northern tropical zone and the occurrence of glaciations in the temperate zones of the Northern Hemisphere. Their general biological adaptation to the absence of circadian stimuli is examined vis-a-vis the fact that biological rhythms are synchronized with the annual flooding events in the subterranean environment. Decouverte historique et progres successifs de la connaissance de la famille des Stenasellidae Dudich, 1924. Caracteres morphologiques originaux; diagnose de la famille; liste mise a jour des genres, nombre de leurs taxons et principales caracteristiques. Biogeographie et ecologie du groupe; relations entre le comportement fouisseur et l'adaptation a la vie dans tous les types de milieux des eaux souterraines continentales. Histoire evolutive presumee de la famille, tenant compte de la capacite d'expansion active de ces Isopodes et du role des evenements quaternaires: developpement du climat aride dans la zone nord-tropicale et intervention des glaciations dans les zones temperees de l'hemisphere nord. Adaptation generale des processus biologiques a l'absence de stimuli externes circadiens, ces processus etant rythmes par la pulsation annuelle du flux des eaux dans l'environnement souterrain, qui joue le role d'un stimulus circannien.

BIOGEOGFIAPHIA - vol‘ XIX - 1997 (Pubblicato il 31 ottobre 1998) Gli effetti delle variazioni climatiche pleistoceniche sulla dinamica dei popolamenti animali e vegetali nella Penisola italiana Uso di marcatori biochimici per lo studio del popolamento stigobio di Sardegna: gli Asellota (Crustacea Isopoda) ROBERTO ARGAN O, GIUSEPPE MESSANA *, ELVIRA DE MATTHAEIS, MARINA COBOLLI, VALERIO KETMAIER Dz'pzz7'tz'mento di Bi0[0gz'zzAm'mzz/6 e a'el[’Uomo, Uni:/ersitiz di Roma qLa Szzpienzzz” * Centre 512' Studio per la Fzzzmistiaz ed Ecologizz Tropiazli, C.N.R., Firmze Keywords: Paleogeography, Genetic divergence, Stygobitic fauna, Stemzxellus, Prozzse/I115. SUMMARY Levels of genetic divergence on several populations belonging to different Asellota species, obtained via allozymic markers, are reported and discussed with the aim to shed light on the dynamic of colonization of Sardinian surface and underground freshwaters. Two Families of Aselloru are here considered: Asellidae (genus Prorttrllm) and Stenasellidae (genus Steizzzsel/21:). Up to date only three species of Stenasellidae were known for Sardinia (S. rzmwitzzzi, S. 22zu'agicu.r, S. rzssaigg/qxii 5.1.). The genus Przmre//12.: is present in Sardinia with populations showing different levels of adaptation to underground environment. We studied three strictly stygobitic populations, five epigean Sardinian populations and one population from Giordania, in the area of the type locality of the species P. coxrzlis, in order to better understand pattern of phylogenetic relationships and colonisation dynamic. Levels of genetic divergence allowed us to hypothesise a model of colonisation of Sardinian freshwaters based on multiple dispersal events. Quaternary climatic changes may be considered responsible of the presently observed pattern of genetic differentiation and of the colonisation of underground waters. Recent researches have led to discover an high number ofSfez1a5e/[Ia populations: levels of genetic divergence among them allowed us to recognise six species at least, whose phylogenetic relationships are discussed taking into account palaeogeographic events that alicecred Sardinia from Miocene to date. INTRODUZIONE Le acque sotterranee della Sardegna racchiudono un importante capitolo della storia del popolamento anirnale dell’isola, ben lontano dall’essere cornpletamente scritto. Questo ambiente, benche avaro di informazioni, costituisce un inesau— ribile campo di studi che consente, tra l’altr0, di saggiare il Valore inforrnativo di rnetodologie diverse, di rnoda e non, messe a confronto. Da qualche anno stiamo tentando drrealizzare un programma organico di ricerche sugli isopodi dulcacquicoli dell’isola, sia per quanto riguarda gli ambien— ti di superficie che quelli sotterranei. Si tratta di organismi di grande interesse biogeografico e, piu in generale, evoluzionistico. Infatti, come e stato piii volte affermato, il rnonofiletismo, che e alla base del- l’intero ordine degli Isopodi, garantisce una sostanziale ornogeneita organizza—

Troglobitic isopods of the family Asellidae, comprising about 42 species (Fleming, 1973), are widespread in the eastern United States, mostly in non-glaciated areas, but extending into some glaciated parts of Illinois and Indiana. To the west, troglobitic asellids range to central Kansas, Oklahoma and Texas. West of this area, if we exclude the 4 Mexican species of Mexistenasellus (Cole and Minckley, 1972; Magniez, 1972; Argano, 1973) which belong to a separate family, Stenasellidae (Henry and Magniez, 1968, 1970), only 2 troglobitic asellids are known from North America: Asellus californicus Miller (1933) from northern California and Conasellus pasquinii Argano (1972) from Veracruz state, Mexico. The 3 new species of western troglobitic asellids described herein extend the records of blind asellids in North America south to Chiapas state, Mexico, and north to central Alberta, Canada (ca. 53''N), and add a second species from California. The new species from Chiapas is very similar to Conasellus pasquinii Argano (1972); the new asellids from Alberta and California show no close affinities with known species. The generic status of North American species of Asellus is still unsettled. Henry and Magniez (1970) divided tlie species between Conasellus Stammer (1932) and ,Pseudobaicalasellus Henry and Magniez (1968) except A. tomalensis Harford and ... A. californicus Miller, which they believed to be closely related to far-eastern forms belonging to Aseltus (Asellus) and Nipponasellus Matsumoto (1962). I have indi" cated that this is unlikely for A. tomalensis (see Bowman, 1974); the case oi A. californicus will be discussed later in this paper. ' '""'*