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Jażdżewska, Anna M., Brandt, Angelika, Arbizu, Pedro Martínez, Vink, Annemiek (2022): Exploring the diversity of the deep sea-four new species of the amphipod genus Oedicerina described using morphological and molecular methods. Zoological Journal of the Linnean Society 194: 181-225, DOI: 10.1093/zoolinnean/zlab032

OEDICERINA HENRICI JAżDżEWSKA, SP. NOV. (FIGS 2–6) Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 9A993D45-B781-4479-A4D6-2EC840D1BC3E. Type material Holotype: ♂, 6.5 mm, body remnants and two slides with appendages, ZMH K-60658, DSB_3762, St. AB2-EB04, 12°07.83’ N, 117°18.67’ W- 12°08.02’ N, 117°17.52’ W, 4111–4122 m, 25 February 2015, leg. Inga Mohrbeck. Paratype: Immature ♂, urosome missing, individual originally in one piece, broke into three parts during examination, one slide with appendages, ZMH K-60659, DSB_3682, St. Ma 16–95, 11°47.862’ N, 117°30.639’ W- 11°47.152’ N, 117°29.490’ W, 4356–4359 m, 9 May 2016, leg. Annika Janssen. Additional material: One ovigerous ♀ (single egg), individual found in two parts, DNA is extracted from the anterior part, posterior part preserved but not used for taxonomic evaluation, ZMH K-60660, DSB_3582, St. SO 262-156, 11°49.381’ N, 117°32.663’ W- 11°49.752’ N, 117°30.760’ W, 4340– 4340 m, 9 May 2018, leg. Pedro Martínez Arbizu. The registered type material is deposited in the Zoological Museum of Hamburg, Germany. Type locality: Eastern central Pacific, CCZ, St. AB 2-EB04, 12°07.83’ N, 117°18.67’ W- 12°08.02’ N, 117°17.52’ W, 4111–4122 m. Etymology: The species is named for Prof. Krzysztof Henryk (Latin Henricus) Jażdżewski, the first author’s father and renowned specialist in amphipod taxonomy, diversity and ecology. Description: Based on male, 6.1 mm, St. AB2-EB04. Head (Fig. 2): longer than deep, longer than pereonites 1–3 combined; no eyes or ocular pigment visible; rostrum strongly deflexed, the angle between head dorsal margin and rostrum margin 90 ° or less, rostrum as long as first article of peduncle of antenna 1; interantennal lobe weak, rounded. Antenna 1 (Fig. 3; broken in holotype at first peduncular article, description based on paratype): length ratios of peduncle articles 1–3 1:0.7:0.3; flagellum broken at 11th article; accessory flagellum 1-articulate, minute, slender, one fourth of the length of first flagellum article; sparse setae placed both on peduncle and flagellar articles. Antenna 2 (Fig. 3; broken in holotype at first peduncular article, description based on paratype): peduncle moderately setose; length of article 4 1.4 × article 5; peduncular article 5 with short setae along dorsal margin; flagellum shorter than peduncle article 5, 7-articulate (but last flagellar articles broken off), sparse setae placed distally on flagellar articles. Upper lip (labrum) (Fig. 3): wider than long, rounded apically, with fine setules laterally. Mandible (Fig. 3): incisor margins with five teeth; left lacinia mobilis five-cusped; right lacinia mobilis narrower with five cusps; accessory spine rows with five-six serrate setae; molar columnar, strongly triturative, denticulate, with one associated seta; palp 3-articulate, article 1 short, article 2 equal in length to article 3, with 9–10 posterodistal setae, article 3 slightly tapering distally, anterior margin with three to four setae, posterior margin with a row of 30 setae of different length. Lower lip (Fig. 3): outer lobes broadly rounded, mandibular lobes narrow; inner lobes large, separate. Maxilla 1 (Fig. 3): inner plate oval, with two distal setae; outer plate with nine acute setal-teeth (three with bifurcate tips); palp 2-articulate, longer than outer plate, slender, rounded apically, article 1 short, length 0.3 × article 2, article 2 with 10–11 apical/subapical setae and two lateral setae. Maxilla 2 (Fig. 3): left— inner plate shorter than outer, right—plates subequal in length, inner plate slightly tapering distally, width about 1.1 × outer, with setae and spines apically and subapically, fine setules along inner margin; outer plate rounded with apical spines and setae, with four apicolateral setae. Maxilliped (Fig. 4) (due to very strong staining of the holotype during preparation for CLSM some setae, especially placed on the surface of maxilliped not visible): inner plate subrectangular, reaching about 0.3 × basal article of palp, apical margin with eight slender spines; outer plate slender and slightly curved, long, reaching almost 0.5 × length of palp article 2, apical and medial margins with setae and small spines; palp 4-articulate, strong; surface of article 2 with minute, triangular scales; article 1 slightly tapering distally; article 2 triangular, widest at the midpoint, with strong medial setae; article 3 expanded mediodistally, but not produced along article 4; article 4 strong, slightly curved; length ratios of articles 1–4 1:1.7:0.7:1. Pereon. Pereonite 1 (Fig. 2) longer than 2, pereonite 3 same length as 2; pereonites 4–5 successively longer; pereonite 6 shorter than pereonite 5, pereonite 7 the longest, extending dorsally into sharp posteriorly directed tooth. Gnathopod 1 (Fig. 4): coxa subtriangular, distinctly produced anteriorly, anterodistal corner narrowly rounded, posterodistal corner rectangular, ventral margin naked, width to depth ratio 1:0.7; basis straight, weakly expanded, distal half of anterior margin with four long setae and c. 10 moderately long setae, posterior margin without setae, single spine at posterodistal corner; merus, posterodistal lobe rounded, moderately setose; carpus strongly expanded, anterior margin naked, posterior lobe subacute with setae along posterior margin and a few setae placed at distal margin; propodus subchelate, triangular, strongly widening distally, anterior margin with four setae in two groups, palm slightly shorter than hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with single spine; dactylus curved, longer than palm. Gnathopod 2 (Figs 4, 5) (broken in holotype at basis; described based on paratype): coxa narrow, slightly tapering distally, width 0.7 × depth, apex rounded, ventral margin naked; basis straight, six thin setae at inner surface of anterior margin, 20 long setae forming circular patch anterodistally, posterior margin with two moderately long setae, single spine at posterodistal corner; merus, posterodistal lobe narrow, moderately setose; carpus strongly expanded, wider than propodus, anterior margin with a few sparsely placed setae, posterodistal lobe subacute, exceeding palm of propodus, distal margin oblique armed with a row of spines, posterior margin with moderately long setae; propodus shorter than carpus, subchelate, triangular, strongly widening distally, anterior margin with six long setae regularly placed, palm shorter than hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with single spine; dactylus curved, longer than palm. Pereopod 3 (Fig. 5): coxa subrectangular, slightly larger than coxa 2, ventral margin naked; basis long and narrow, length 4.5 × width, posterior margin with traces of three short setae, single short spine at posterodistal corner; merus expanded distally, almost naked; carpus length 1.2 × merus, posteriorly armed with long setae organized in eight groups; propodus length 0.6 × carpus, with three groups of long setae anterodistally and c. 15 moderately long setae along posterior margin; dactylus thin, shorter than propodus (0.7 × propodus). Pereopod 4 (Fig. 6): right—coxa wider than deep, anterior margin slightly convex, posteroventral lobe huge, blunt, slightly narrowing distally (width to depth ratio of the lobe 1:0.5), posterior margin deeply excavated; basis long and narrow, length 5.8 × width, single short spine at posterodistal corner; merus weakly expanded; carpus-dactylus broken off; left—coxa partially damaged, not dissected; basis long and narrow, length 6 × width, two short setae along posterior margin, single short spine at posterodistal corner; merus weakly expanded; carpus subequal in length to merus, posteriorly armed with long setae organized in eight groups; propodus length 0.6 × carpus, with three groups of long setae anterodistally and long setae along posterior margin; dactylus slender, shorter than propodus (0.8 × propodus). Pereopod 5 (Fig. 6): coxa bilobed (partly broken); basis narrow, length 3.4 × width, traces of nine setae along distal half of anterior margin, two short setae at anterodistal corner; merus length 0.9 × basis, with traces of four setae along anterior margin; carpus 0.5 × length of merus armed with 13 setae organized in four groups along posterior margin; propodus slender, 1.1 × length of merus, with groups of setae at posterior margin and at lateral surface; dactylus slender, length 0.7 × propodus. Pereopod 6 (Fig. 6): coxa bilobed but anterior lobe very small, posterior lobe long, distal margin slightly convex; basis narrow, length 3.1 × width, traces of nine setae along distal half of anterior margin, one short seta at anterodistal corner; merus length 0.7 × basis; carpus-dactylus broken off. Pereopod 7 (Fig. 6): coxa wider than deep, rounded posteriorly; basis ovate, length 1.7 × width, tapering distally, anterior margin strongly convex with a few sparse short setae, posterior margin rather straight, crenate, posterodistal lobe absent; merus as long as basis with a few setae along anterior and posterior margins; carpus-dactylus broken off. Pleon. Pleonites 1–2 (Fig. 2) with mid-dorsal, relatively long posteriorly directed teeth; pleonite 3 with short, slender, posteriorly directed tooth. Epimera: 1–3 evenly rounded, epimeron 3 crenulated. Pleopods [pleopod 2 (Fig. 6)]: powerful, peduncles and rami long. Urosome. Urosomite 1 (Fig. 2) longest, with a small hump on dorsal surface in the mid length of the urosomite and a distinct, sharp upright tooth at the posterior margin; urosomite 3 longer than 2, depressed anteriorly, with acute mid-dorsal projection over telson. Uropods: damaged. Telson (Fig. 6): short, length 1.4 × width, cleft 45%, lobes apically damaged, widely diverging, with one seta on dorsal surface. Intraspecific variation: Due to the bad condition of the individuals not much can be said about sexual or size-dependent dimorphism within the studied species. The only observed difference is the smaller size of the posterodorsal tooth on pleonite 3 in the immature male. Molecular identification: Following the definition given by Pleijel et al. (2008), the sequence of the holotype male of O. henrici (ZMH K-60658, GenBank accession number MW 377935) is designed as a hologenophore of all obtained sequences. The sequences of the paratype and an additional individual of the species are deposited in GenBank with the following accession numbers: MW 377932, MW 377937. The species has also received a Barcode Index Number from BOLD: AEB1524 (dx.doi. org/10.5883/ BOLD: AEB1524). Distribution: Eastern central Pacific, CCZ (Fig. 25), 4111–4359 m.

OEDICERINA CLAUDEI JAżDżEWSKA, SP. NOV. (FIGS 19–23) Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: D1CB7EA5-FC38-406F-A101-BC5EBE7E1762. Type material Holotype: Juvenile, 4.5 mm, body remnants and two slides with appendages, SMF-56781, St. AKL-71-1-9, 46°05.037’ N, 146°00.465’ E- 46°08.727’ N, 146°00.227’ E; 3307– 3307 m, 10 July 2015, leg. Marina V. Malyutina. The registered type material is deposited in the Senckenberg Museum (Frankfurt, Germany). Type locality: Sea of Okhotsk, St. AKL-71-1-9, 46°05.037’ N, 146°00.465’ E- 46°08.727’ N, 146°00.227’ E; 3307– 3307 m. Etymology: The species is named for Dr. Claude De Broyer, a great friend and one of the first author’s scientific mentors and renowned specialist in amphipod taxonomy, diversity and ecology. Description: Based on juvenile, 4.5 mm, St. AKL-71-1-9. Head (Fig. 19): longer than deep, longer than pereonites 1–4 combined; no eyes or ocular pigment visible; rostrum deflexed, the angle between head dorsal margin and rostrum margin almost 90 °, rostrum reaching the end of first article of peduncle of antenna 1; interantennal lobe indistinct. Antenna 1 (Fig. 20): length ratios of peduncle articles 1–3 1:0.7:0.4, peduncle article 1 laterally acutely produced; flagellum 5-articulate, first article as long as article 3 of peduncle; accessory flagellum 1-articulate, minute, slender, length 0.2 × first flagellum article; peduncle and flagellum sparsely setose. Antenna 2 (Fig. 20, considerably damaged): length of peduncle article 4 1.5 × article 5. Upper lip (labrum) (Fig. 20): wider than long, rounded apically, with fine setules laterally. Mandible (Fig. 20): incisor margins with five teeth; left lacinia mobilis four-cusped; right lacinia mobilis narrower slightly cuspidate; accessory spine rows with five serrate setae; molar columnar, strongly triturative, denticulate, with one associated seta; palp 3-articulate, article 1 short, article 2 1.1 × longer than article 3, with four posterodistal setae, article 3 slightly tapering distally, anterior margin with two setae, posterior margin with two setae, three setae at apex. Lower lip (Fig. 20): outer lobes broadly rounded, mandibular lobes narrow; inner lobes large, separate. Maxilla 1 (Fig. 20): inner plate oval, with two distal setae; outer plate with eight acute setal-teeth (three with bifurcate tips); palp 2-articulate, longer than outer plate, slender, rounded apically, article 1 short, length 0.2 × article 2, article 2 with five or six apical/subapical setae and one long, lateral setae. Maxilla 2 (Fig. 20): left—plates subequal in length, right—inner plate shorter than outer, inner plate width about 1.1 × outer, with setae and spines apically and subapically, fine setules along inner margin; outer plate rounded with apical spines and setae, outer margin with fine setules. Maxilliped (Fig. 21): inner plate subrectangular, reaching about 0.3 × basal article of palp, apical margin with six slender spines; outer plate slender and slightly curved, long, reaching 0.4 × length of palp article 2, apical and medial margins with setae and small spines; palp 4-articulate, strong; article 1 tapering distally; article 2 triangular, widest at 0.6 × length, setose medially; article 3 expanded mediodistally, slightly produced along article 4; article 4 strong, slightly curved; length ratios of articles 1–4 1:1.9:0.7:1.3. Pereon. Pereonite 1 (Fig. 19) twice as long as pereonite 2, pereonite 3 longer than 2, pereonites 4–5 subequal in length, longer than pereonites 1–3, pereonites 6–7 of the same length, longer than all preceding segments. Gnathopod 1 (Figs 19, 21): coxa subtriangular, anterodistal corner bluntly rounded, posterodistal corner rectangular, ventral margin naked, width to depth ratio 1:0.8; basis straight, slightly expanded distally, distal half of anterior margin with row of long setae, sparse setae on the surface; merus, posterodistal lobe subquadrate, moderately setose; carpus strongly expanded, anterior margin with five setae along distal half, posterior lobe subacute with setae along posterior and distal margins; propodus subchelate, triangular, strongly widening distally, anterior margin moderately setose, palm longer than hind margin, transverse, strongly convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with one spine; dactylus curved, longer than palm. Gnathopod 2 (Figs 19, 21): coxa narrow, slightly tapering distally, width 0.4 × depth, apex rounded, ventral margin naked; basis straight, 16 long setae forming circular patch anterodistally, single moderately long, delicately plumose seta at posterior margin; merus, posterodistal lobe rounded, moderately setose; carpus strongly expanded, wider than propodus, anterior margin with four setae (some delicately plumose), posterodistal lobe subacute, extending palmar corner of propodus, distal margin oblique armed with a row of spines, posterior margin with moderately long setae; propodus shorter than carpus, subchelate, triangular, strongly widening distally, anterior margin with eight long setae regularly placed, palm shorter than hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with one spine; dactylus curved, slightly longer than palm. Pereopod 3 (Figs 19, 22): coxa subrectangular, wider and deeper than coxa 2, ventral margin naked; basis shorter than coxa, narrow, length 3.1 × width, anterior and posterior margins with some long, delicately plumose setae; merus expanded distally, one group of setae anterodistally and two groups of setae posteriorly; carpus broad, length 1.2 × merus, posteriorly armed with long setae; propodus length 0.8 × carpus, with six long setae anterodistally and seven long setae along posterior margin; dactylus stout, longer than propodus (1.2 × propodus). Pereopod 4 (Figs 19, 22): coxa wider than deep, anterior margin strongly convex, extending distally, coxa the widest almost at 2/3 of its depth, ventral margin naked, posteroventral lobe huge, blunt, (width to depth ratio of the lobe 1:0.9), posterior margin deeply excavated; basis long and narrow, length 3.5 × width, anterior margin with four long, delicately plumose setae, posterior margin with one long, delicately plumose setae, short seta at posterodistal corner; merus expanded, a few setae at anterior margin, one short seta at posterior margin, group of long setae at posterodistal corner; carpus expanded, length 0.8 × merus, five setae at anterodistal corner, posterior margin armed with 11 long and moderately long setae; propodus narrow, length 0.5 × carpus, moderately setose at anterior and posterior margins; dactylus stout, longer than propodus (1.9 × propodus). Pereopod 5 (Fig. 22): right—coxa about as deep as coxa 4, bilobed, posterior lobe expanded ventrally, ventral margin straight, naked, anterior lobe 0.5 × depth of posterior lobe; basis narrow, length 4.1 × width, five long, delicately plumose setae at anterior margin; merus as long as basis, with three groups of moderately long plumose setae along anterior margin, seven setae at anterodistal corner, two setae at posterior margin and a group of four setae at posterodistal corner; carpusdactylus broken off; left—coxa about as deep as coxa 4, bilobed, posterior lobe partially damaged; basis narrow, length 2.5 × width, two long, delicately plumose setae at anterior margin, two long setae at the surface (one delicately plumose); merus 1.1 × basis, with three groups of moderately long setae along anterior margin, four setae at anterodistal corner, two setae at posterior margin; carpus length 0.5 × merus, with five setae anterodistally; propodus length 1.6 × carpus length, with three setae anterodistally; dactylus stout, longer than propodus (1.2 × propodus length). Pereopod 6 (Fig. 22): coxa bilobed but anterior lobe very small, posterior lobe long, distal margin slightly convex; basis narrow, length 3.9 × width, anterior margin with seven long, delicately plumose setae along distal half, posterior margin with five long, delicately plumose setae along distal half; merus length 0.7 × basis, three rows of setae anteriorly, two rows of setae posteriorly; carpusdactylus broken off. Pereopod 7 (Fig. 22): coxa wider than deep, rounded posteriorly; basis ovate, length 1.5 × width, widest in the mid-length, tapering distally, anterior margin strongly convex, two short spines at anterodistal corner, posterior margin slightly oblique in distal half, smooth, posterodistal lobe nearly as long as ischium; merus length 1.2 × basis with groups of setae both anteriorly and posteriorly (some setae broken); carpus-dactylus broken off. Pleon. Pleonite 1 (Fig. 19) produced posteriorly, pleonites 2–3 with distinct mid-dorsal, posteriorly directed teeth. Epimera: 1 and 3 evenly rounded, epimeron 2 posterior margin convex, posterodistal corner subquadrate. Pleopods [pleopod 2 (Fig. 23)]: powerful, peduncles and rami long. Urosome. Urosomite 1 (Fig. 19) longest; urosomite 3 longer than 2. Uropods (Fig. 23): Uropod 1: peduncle length 1.1 × inner ramus, margins with some short setae; inner ramus 1.4 × length of outer ramus, rami with sparse setae. Uropod 2: shorter than uropod 1, peduncle length 0.9 × inner ramus, with some short setae; inner ramus 1.2 × length of outer ramus, rami with sparse setae. Uropod 3: peduncle short, peduncle length 0.4 × inner ramus; inner ramus with short spines along distal half of lateral margins; outer ramus damaged. Telson: (Fig. 23) short, length 1.7 × width, cleft 40%, lobes subacute, widely diverging, notched subapically, tips unequal in size (inner longer than outer), single seta placed in the notch, single dorsolateral seta on the surface. Sexual dimorphism: No sexual or size-dependent variation observed as the individual is unique. Molecular identification: Following the definition given by Pleijel et al. (2008), the sequence of the holotype juvenile of O. claudei (SMF-56781, GenBank accession number MW 377945) is designed as a hologenophore of all obtained sequences. The species has received also a Barcode Index Number from BOLD: AEA4699 (dx.doi. org/10.5883/ BOLD: AEA 4699). Distribution: Sea of Okhotsk (Fig. 25), 3307 m. MOLECULAR INVESTIGATION Each of the morphologically recognized species received a unique Barcode Index Number. Across all species, the intraspecific diversity calculated on haplotypes is low, ranging from 0.002 (O. lesci) to 0.005 (O. henrici) for both K2P and p -distance. Each of the species is represented by three haplotypes (Table 2; Fig. 24B). An exception is O. claudei, as only one individual of this taxon was collected. The distances between the studied taxa varies from 0.059 to 0.238 of p -distance and from 0.061 to 0.289 of K2P (Table 3). The lowest interspecies distances are noted between O. lesci and O. ingolfi, irrespective of the measures applied. The highest values are observed for O. henrici and O. claudei for both measures and for O. henrici and O. ingolfi for p -distance only (Fig. 24A). The haplotype networks show a star-like topology (Fig. 24B). In O. lesci, the central, ancestral and dominant haplotype is present at five stations including the stations situated on both sides of the KKT. In O. henrici and O. teresae, the central, ancestral haplotypes are missing.

OEDICERINA LESCI JAżDżEWSKA, SP. NOV. (FIGS 13–18) Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 8242F310-A152-4CB7-8BE3-EAAF8A848D9A.

OEDICERINA TERESAE JAżDżEWSKA, SP. NOV. (FIGS 7–12) Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 8B11C501-328E-4F33-AA78-F2229D4847A1. Type material Holotype: Immature ♂, 5.5 mm, body remnants and two slides with appendages, ZMH K-60661, DSB_3680, St. Ma 16–25, 11°49.143’ N, 116°58.492’ W- 11°49.975’ N, 116°57.797’ W; 4107– 4101 m, 29 April 2016, leg. Annika Janssen. Allotype: Mature ♀ (oostegites setose, no egg), 5.8 mm, ZMH K-60662, DSB_3818, St. AB2-EB12, 12°02.72’ N, 117°25.43’ W- 12°03.03’ N, 117°24.28’ W; 4223–4299 m, 16 March 2015, leg. Inga Mohrbeck. Paratype: One juvenile, 3.4 mm, ZMH K-60663, DSB_3681, St. Ma 16–28, 11°49.654’ N, 117°00.299’ W- 11°49.902’ N, 116°59.174’ W; 4143 – 4133 m, 1 May 2016, leg. Annika Janssen. Additional material: One individual sex undetermined, broken in two parts, DNA extracted from anterior part, posterior part preserved but not used for taxonomic evaluation, ZMH K-60664, DSB_3683, St. Ma 16–95, 11°47.862’ N, 117°30.639’ W- 11°47.152’ N, 117°29.490’ W, 4356–4359 m, 9 May 2016, leg. Annika Janssen. The registered type material is deposited in the Zoological Museum of Hamburg, Germany. Type locality: Eastern central Pacific, CCZ, St. Ma 16–25, 11°49.143’ N, 116°58.492’ W- 11°49.975’ N, 116°57.797’ W; 4107– 4101 m. Etymology: The species is named for Dr. Teresa Jażdżewska, the first author’s mother and a specialist in ephemeropteran and hirudinean taxonomy, diversity and ecology. Description: Based on male, 5.5 mm, St. Ma 16–25. Head (Fig. 7): longer than deep, longer than pereonites 1–2 combined; no eyes or ocular pigment visible; rostrum curved but not deflexed, the angle between head dorsal margin and rostrum margin more than 90 °, rostrum reaching 2/3 of first article of peduncle of antenna 1; interantennal lobe moderate, subtriangular. Antenna 1 (Fig. 8): subequal in length to antenna 2; length ratios of peduncle articles 1–3 1:0.7:0.4; flagellum 12-articulate, first article longer than article 3 of peduncle; accessory flagellum 1-articulate, minute, slender, length 0.1 × first flagellum article; peduncle sparsely setose, flagellum naked. Antenna 2 (Fig. 8): peduncle moderately setose; length of article 4 0.9 × article 5; flagellum broken at sixth article (right antenna 2–7-articulate). Upper lip (labrum) (Fig. 8): damaged during preparation. Mandible (Fig. 8): incisor margins with five (left) or six (right) teeth; left lacinia mobilis six-cusped; right lacinia mobilis narrower with four cusps; accessory spine rows with four slender, pectinate spines; molar columnar, strongly triturative, denticulate, with one associated seta; palp 3-articulate, article 1 short, article 2 length 0.7 × article 3, with seven posterodistal setae, article 3 slightly tapering distally, anterior margin with three (left) or four (right) setae, posterior margin with 11 setae, apically with two or three setae. Lower lip (Fig. 8): outer lobes broadly rounded, mandibular lobes narrow; inner lobes large, separate. Maxilla 1 (Fig. 8): inner plate oval, with two distal setae; outer plate with eight acute setal-teeth (three/four with bifurcate tips); palp 2-articulate, longer than outer plate, robust, rounded apically, article 1 short, length 0.25 × article 2, article 2 with eight apical/subapical setae and one long, lateral setae. Maxilla 2 (Fig. 8): inner plate wider than outer, right inner plate also shorter than outer (left subequal in length), inner plate with setae and spines apically and subapically, fine setules along inner and outer margins; outer plate rounded with apical spines and setae, with one moderately long apicolateral setae. Maxilliped (Fig. 9): inner plate subrectangular, reaching about 0.3 × basal article of palp, apical margin with seven slender spines; outer plate slender and slightly curved, long, reaching 0.5 × length of palp article 2, apical and medial margins with setae and small spines; palp 4-articulate, strong; article 1 tapering distally; article 2 triangular, widest at the midpoint, with strong medial setae; article 3 expanded mediodistally, not produced along article 4; article 4 strong, slightly curved; length ratios of articles 1–4 1:1.8:0.7:1. Pereon. Pereonite 1 (Fig. 7) longer than pereonite 2, pereonites 3–6 of similar length, longer than 2, pereonite 7 the longest, extending dorsally into a sharp posteriorly directed tooth. Gnathopod 1 (Fig. 9): coxa subtriangular, anterodistal corner subacute, posterodistal corner rectangular, ventral margin with single short seta anteriorly placed, width to depth ratio 1:1; basis straight, slightly expanded distally, distal half of anterior margin with row of long setae, posterior margin with long setae (some delicately plumose), posterodistal corner with single spine, some short setae on the inner surface; merus, posterodistal lobe rounded, moderately setose; carpus strongly expanded, anterior margin with six setae along distal half (some delicately plumose), posterior lobe rounded with setae along posterior and distal margins; propodus subchelate, triangular, strongly widening distally, anterior margin moderately setose, palm almost as long as hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with one spine; dactylus curved, distinctly longer than palm. Gnathopod 2 (Fig. 10): coxa narrow, slightly tapering distally, width 0.5 × depth, apex rounded, ventral margin naked; basis straight, c. 15 long setae forming circular patch anterodistally, four long setae at posterior margin, three setae at posterodistal corner, some setae at the surface; merus, posterodistal lobe narrow, subacute, moderately setose; carpus strongly expanded, wider than propodus, anterior margin with two setae, posterodistal lobe subacute, extending palmar corner of propodus, distal margin oblique armed with a row of spines, posterior margin with moderately long setae; propodus longer than carpus, subchelate, triangular, strongly widening distally, anterior margin with four long setae regularly placed, group of setae at anterodistal corner, palm shorter than hind margin, transverse, convex, margin crenate, with fine denticulations, with medial spines and lateral row of submarginal setules, palmar corner subrectangular with one spine; dactylus curved, just longer than palm. Pereopod 3 (Fig. 10): coxa subrectangular, wider and deeper than coxa 2, ventral margin naked; basis longer than coxa, narrow, length 5.4 × width, some long setae anteriorly; merus slightly expanded distally, two groups of setae anterodistally and three groups of setae posteriorly; carpus narrow, length 1.1 × merus, one group of setae at anterodistal corner, posteriorly armed with long setae organized in eight groups; propodus length 0.6 × carpus, with a group of setae anterodistally and five groups of moderately long setae along posterior margin; dactylus thin, as long as propodus. Pereopod 4 (Fig. 10): coxa wider than deep, anterior margin strongly convex, extending distally, coxa the widest almost at 2/3 of its depth, ventral margin naked, posteroventral lobe huge, blunt (width to depth ratio of the lobe 1:0.7), posterior margin deeply excavated; basis long and narrow, length 5.4 × width, sparse long setae at anterior and posterior margin as well as on the surface; merus slightly expanded, sparsely setose; carpus-dactylus broken off. Pereopod 5 (Fig. 11): coxa about as deep as coxa 4, bilobed, posterior lobe expanded ventrally, ventral margin straight, with one seta anteriorly placed, anterior lobe 0.5 × depth of posterior lobe; basis narrow, length 2.8 × width, five long, delicately plumose setae at anterior margin, three long setae along posterior margin; merus as long as basis, sparsely setose; carpus-dactylus broken off. Pereopod 6 (Fig. 11): coxa partly damaged; basis narrow, length 3.3 × width, sparsely setose; merus as long as basis, sparsely setose; carpus-dactylus broken off. Pereopod 7 (Fig. 11): coxa wider than deep, rounded posteriorly; basis ovate, length 1.6 × width, widest in the mid length, tapering distally, anterior margin strongly convex, one short spine at anterodistal corner, posterior margin slightly oblique in distal half, denticulate, posterodistal lobe absent; merus distally damaged, with groups of setae both anteriorly and posteriorly (some setae broken); carpus-dactylus broken off. Pleon. Pleonites 1–3 (Fig. 7) with distinct mid-dorsal, posteriorly directed teeth. Epimera: 1 and 3 evenly rounded, epimeron 2 posterodistal corner subquadrate, epimeron 3 delicately serrate. Pleopods [pleopod 1 (Fig. 12)]: powerful, peduncles and rami long. Urosome. Urosomite 1 (Fig. 7) longest, produced distally into a sharp, large, upright tooth; urosomite 3 longer than 2. Uropods (Fig. 12): Uropod 1 (damaged): peduncle margins with some moderately long setae; rami broken off. Uropod 2 (rami damaged): peduncle with some moderately long setae; inner ramus with sparse setae. Uropod 3: peduncle short, peduncle length 0.3 × inner ramus; inner and outer ramus with short spines along lateral margins. Telson: (Fig. 12) short, length 1.5 × width, cleft 35%, lobes subacute, widely diverging, notched subapically, tips unequal in size (inner slightly shorter than outer; on one side outer tip broken), single seta placed in the notch. Intraspecific variation: No distinct differences were observed between the holotype and the mature female collected. The difference between adult individuals and the juveniles is expressed by the number of articles of flagella of antenna 1 and antenna 2 which is smaller in the latter. Molecular identification: Following the definition given by Pleijel et al. (2008), the sequence of the holotype male of O. teresae (ZMH K-60661, GenBank accession number MW 377944) is designed as a hologenophore of all obtained sequences. The sequences of the paratype and additional individuals of the species are deposited in GenBank with the following accession numbers: MW 377925, MW 377934, MW 377942. The species has received also a Barcode Index Number from BOLD: AEB1523 (dx.doi.org/10.5883/ BOLD: AEB1523). Distribution: Eastern central Pacific, CCZ (Fig. 25), 4101–4359 m.

GENUS OEDICERINA STEPHENSEN, 1931 Known species: Oedicerina ingolfi Stephensen, 1931; O. megalopoda Ledoyer, 1986; O. denticulata Hendrycks & Conlan, 2003; O. loerzae Coleman & Thurston, 2014; O. vaderi Coleman & Thurston, 2014., Published as part of Ja��d��ewska, Anna M., Brandt, Angelika, Arbizu, Pedro Mart��nez & Vink, Annemiek, 2022, Exploring the diversity of the deep sea-four new species of the amphipod genus Oedicerina described using morphological and molecular methods, pp. 181-225 in Zoological Journal of the Linnean Society 194 on page 186, DOI: 10.1093/zoolinnean/zlab032, http://zenodo.org/record/5799308, {"references":["Stephensen K. 1931. Crustacea Malacostraca VII (Amphipoda III). The Danish Ingolf-Expedition 3: 179 - 290.","Ledoyer M. 1986. Crustaces amphipodes gammariens. Familles des Haustoriidae a Vitjazianidae. Faune de Madagascar 59 (2). Paris: ORSTOM Institut Francais de Recherche Scientifique pour le Developement en Cooperation, 599 - 1112.","Hendrycks EA, Conlan KE. 2003. New and unusual abyssal gammaridean Amphipoda from the north-east Pacific. Journal of Natural History 37: 2303 - 2368.","Coleman CO, Thurston MH. 2014. A redescription of the type species of Oedicerina Stephensen, 1931 (Crustacea, Amphipoda, Oedicerotidae) and the description of two new species. Zoosystematics and Evolution 90: 225 - 247."]}

LEPECHINELLA SKARPHEDINI THURSTON, 1980 Lepechinella skarphedini Thurston, 1980: 78���81, figs 7���9. ��� Barnard & Karaman, 1991: 269. Type locality: North Atlantic, Iceland Basin, 60��7.5���N, 19��32.4���W, 2646 m (Discovery station 7709#72). Material examined: DZMB-HH 52661, one specimen; ZMH-K 56639, one specimen, IceAGE, ME 85-3, station 1054, Irminger Basin, south Iceland, North Atlantic (61��36.19���N, 031��22.60���W to 61��36.97���N, 031��22.18���W), 2537.3 m, 7 September 2011. Remarks: The two specimens collected here provide additional records of L. skarphedini, extending the known distribution further north from the Iceland Basin to the Irminger Basin. Depth range: 2450 to 2537 m. Distribution: Irminger Basin (present study) and Iceland Basin (Thurston, 1980) (Fig. 9A; Tables 1, 2)., Published as part of L��rz, Anne-Nina, Brix, Saskia, Ja��d��ewska, Anna M. & Hughes, Lauren Elizabeth, 2020, Diversity and distribution of North Atlantic Lepechinellidae (Amphipoda: Crustacea), pp. 1095-1122 in Zoological Journal of the Linnean Society 190 on page 1110, DOI: 10.1093/zoolinnean/zlaa024, http://zenodo.org/record/5722220, {"references":["Thurston MH. 1980. Abyssal benthic Amphipoda (Crustacea) from the East Iceland Basin 2. Lepechinella and an allied new genus. Bulletin British Museum of Natural History (Zoology) 38: 69 - 87.","Barnard JL, Karaman G. 1991. The families and genera of marine gammaridean Amphipoda (except marine gammaroids). Records of the Australian Museum 13: 1 - 866."]}

LEPECHINELLA CHRYSOTHERAS STEBBING, 1908 Lepechinella chrysotheras Stebbing, 1908: 191���193, pl. 27. ��� K.H. Barnard, 1925: 356���357. ��� Stephensen, 1944: 19. ��� J. L. Barnard, 1973: 14. ��� Barnard & Karaman, 1991: 269. Type locality: North Atlantic, North Sea (between Orkney Islands and Shetland Islands), 59��041���N, 3��08���W, 850 m. Remarks: Lepechinella chrysotheras is not encountered in the samples from IceAGE expeditions. This species is only known from the holotype of Stebbing (1908) and three additional male specimens listed by Stephensen (1944). There are currently no reported female specimens of L. chysotheras. Stebbing (1908) does not list the institution where the type material is deposited and, unfortunately, no type material for L. chrysotheras was located at the NHM, London, which was the main repository of Stebbing���s personal collection. Stebbing (1908) cited material as collected in the ���North Sea���, by the RV Goldseeker, but this is a historic use of the name North Sea, as in more recent times, the term ���North Sea��� is restricted to the region between the United Kingdom and the European mainland. Most importantly, the type locality listed in the formal taxonomic description of the species is given only as latitude and longitude coordinates. Following these coordinates, the collection locality is positioned between the Orkney Islands and the Outer Hebrides, hence outside the modern definition of the North Sea (a technical, but critical point in assessing regional listings and geographic species ranges). Depth range: 850 to 900 m. Distribution: North Atlantic, between Orkney Islands and Shetland Islands (Stebbing, 1908), South of the Faeroes (Stephensen, 1944) (Fig. 9B; Tables 1, 2)., Published as part of L��rz, Anne-Nina, Brix, Saskia, Ja��d��ewska, Anna M. & Hughes, Lauren Elizabeth, 2020, Diversity and distribution of North Atlantic Lepechinellidae (Amphipoda: Crustacea), pp. 1095-1122 in Zoological Journal of the Linnean Society 190 on pages 1104-1106, DOI: 10.1093/zoolinnean/zlaa024, http://zenodo.org/record/5722220, {"references":["Stebbing TRR. 1908. On two new species of northern Amphipoda. Journal of the Linnean Society of London, Zoology 30: 191 - 197, pls 27 - 28.","Stephensen K. 1944. The zoology of east Greenland, Amphipoda. Meddelelser om Gronland 121: 1 - 165.","Barnard JL. 1973. Deep-sea Amphipoda of the genus Lepechinella (Crustacea). Smithsonian Contributions to Zoology 133: 1 - 40.","Barnard JL, Karaman G. 1991. The families and genera of marine gammaridean Amphipoda (except marine gammaroids). Records of the Australian Museum 13: 1 - 866."]}

FAMILY LEPECHINELLIDAE SCHELLENBERG, 1926 Dorbanellidae Schellenberg, 1925: 205. Lepechinellidae Schellenberg, 1926: 344; Barnard, 1932: 186; Dahl, 1959: 235; Andres & Brandt, 2001: 79; Sittrop & Serejo, 2009: 474; Johansen & Vader, 2015: 3. Lepechinellinae Bousfield & Kendall, 1994: 31; Lowry & Myers, 2017: 57. Type genus: Lepechinella Stebbing, 1908, by original designation., Published as part of L��rz, Anne-Nina, Brix, Saskia, Ja��d��ewska, Anna M. & Hughes, Lauren Elizabeth, 2020, Diversity and distribution of North Atlantic Lepechinellidae (Amphipoda: Crustacea), pp. 1095-1122 in Zoological Journal of the Linnean Society 190 on page 1102, DOI: 10.1093/zoolinnean/zlaa024, http://zenodo.org/record/5722220, {"references":["Schellenberg A. 1926. Die Gammariden der Deutschen Sudpolar-Expedition 1901 - 1903. Deutsche Sudpolar- Expedition 1901 - 1903 18: 235 - 414.","Schellenberg A. 1925. Die Gammariden Spitzbergens nebst einer Uebersicht der von Romer & Shaudinn 1898 im nordlichen Eismeer gesammelten Arten. Mitteilungen aus dem Zoologischen Museum in Berlin 11: 169 - 231.","Barnard KH. 1932. Amphipoda. Discovery Reports 5: 1 - 326, pl. 1.","Dahl E. 1959. Amphipoda from depths exceeding 6000 meters. Galathea Report 1: 211 - 241.","Andres HG, Brandt A. 2001. Lepechinellid genera Paralepechinella Pirlot, 1933 and Lepechinelloides Thurston, 1980: first records from Antarctica (Crustacea: Amphipoda). Mitteilungen aus dem Naturhistorischen Museum in Hamburg 98: 77 - 97.","Sittrop DJ, Serejo CS. 2009. Three new species of the genus Lepechinella (Amphipoda: Gammaridea: Lepechinellidae) collected from Campos Basin slope, RJ, Brazil. Scientia Marina 73: 473 - 485. iSSn: 0214 - 8358. doi: 10.3989 / scimar. 2009.73 n 3473","Johansen PO, Vader W. 2015. New and little known species of Lepechinella (Crustacea, Amphipoda, Lepechinellidae) and an allied new genus Lepesubchela from the North Atlantic. European Journal of Taxonomy 127: 1 - 35.","Bousfield EL, Kendall JA. 1994. The amphipod superfamily Dexaminoidea on the North American Pacific coast; families Atylidae and Dexaminidae: systematics and distributional ecology. Amphipacifica 1: 3 - 66.","Lowry JK, Myers AA. 2017. A phylogeny and classification of the Amphipoda with the establishment of the new order Ingolfiellida (Crustacea: Peracarida). Zootaxa 4265: 1 - 89.","Stebbing TRR. 1908. On two new species of northern Amphipoda. Journal of the Linnean Society of London, Zoology 30: 191 - 197, pls 27 - 28."]}

Lörz, Anne-Nina, Brix, Saskia, Jażdżewska, Anna M., Hughes, Lauren Elizabeth (2020): Diversity and distribution of North Atlantic Lepechinellidae (Amphipoda: Crustacea). Zoological Journal of the Linnean Society 190: 1095-1122, DOI: 10.1093/zoolinnean/zlaa024, URL: https://academic.oup.com/zoolinnean/advance-article/doi/10.1093/zoolinnean/zlaa024/5825067

LEPECHINELLA VICTORIAE JOHANSEN & VADER, 2015 (FIGS 4–5, 13) Lepechinella victoriae Johansen & Vader, 2015: 23–28, figs 13–16. Type locality: North Atlantic, south of Iceland, 61°38.2’N, 16°27.7’W, 2355 m. Material examined: DZMB-HH 52527, six specimens, IceAGE 2, POS 456, station 879, Faeroe Islands Ridge, North Atlantic (63°06.10’N, 008°34.32’W to 63°05.62’N, 008°36.22’W), 510.9 m, 31 July 2013. ZMH-K 56620, one specimen, 7.2 mm (Figs 4, 12), IceAGE, ME 85-3, station 963, Iceland Basin, south Iceland, North Atlantic (60°02.73’N, 021°28.06’W to 60°02.73’N, 021°29.88’W), 2749 m, 28 August 2011. ZMH-K 56641, one specimen; IceAGE ME 85-3, station 967, Iceland Basin, south Iceland, North Atlantic (60°02.770’N, 21°28.540’W to 0°02.780’N, 21°30.070’W) 2750.4 m, 28 August 2011. ZMH-K 56621, one specimen, IceAGE, ME 85-3, station 979, Iceland Basin, south Iceland, North Atlantic (60°21.48’N, 018°08.24’W to 60°20.72’N, 018°08.60’W), 2567.6 m, 30 August 2011. DZMB-HH 56897, one specimen; DZMB-HH 56898, one specimen; DZMB-HH 56899, one specimen; DZMB-HH, 52119, one specimen; DZMB-HH 56149, one specimen (3.7 mm, Fig. 4), IceAGE, ME 85-3, station 983, Iceland Basin, south Iceland, North Atlantic (60°21.440’N, 18°08.140’W to 60°02.730’N, 18°08.510’W), 2567.7 m, 30 August 2011. DZMB-HH 56695, one specimen, IceAGE, ME 85-3, station 1119, Denmark Strait, east Greenland, North Atlantic (67°12.81’N, 026°14.50’W to 67°12.83’N, 026°13.51’W), 696.9 m, 14 September 2011. Remarks: Material reported here are larger specimens, 7.2 mm, (Figs 4, 5, 13), than the holotype ZMBN 99134, 5.5 mm. The IceAGE material includes additional juvenile and female specimens from sites close to the type locality ‘south of Iceland’ and at a similar 2000–m depth range. The rostrum shape, lateral cephalic lobe and head anteroventral lobe show some variation between juveniles, with more slender projections, and adults, which have broader and more sinusoidal projections (Fig. 4). The present study extends the known distribution of L. victoriae north to the Denmark Strait and east to the Faeroe Islands Ridge. The collection data also broadens the bathymetric range from the middle bathyal (2355 m) to the shallower upper bathyal (at 679 m deep). Depth range: 679 to 2750 m. Distribution: Iceland Basin (Johansen & Vader, 2015; present study), Denmark Strait (present study), Faeroe Islands Ridge (present study) (Fig. 7B; Tables 1, 2).

LEPECHINELLOIDES KARII THURSTON, 1980 Lepechinelloides karii Thurston, 1980: 83���86, figs 10���12. ��� Barnard & Karaman, 1991: 269. Type locality: North Atlantic, Iceland Basin, 60��07.5���N, 19��26.6���W, 2646 m (Discovery station 7709#72). Material examined: ZMH-K 56629, one specimen, IceAGE ME 85-3, station 967, Iceland Basin, south Iceland, North Atlantic (60��02.770���N, 21��28.540���W to 0��02.780���N, 21��30.070���W) 2750.4 m, 29 August 2011. ZMH-K 56630 one specimen, IceAGE, ME 85-3, station 979, Iceland Basin, south Iceland, North Atlantic (60��21.48���N, 018��08.24���W to 60��20.72���N, 018��08.60���W), 2567.6 m, 30 August 2011. Remarks: The two specimens recorded from the IceAGE expedition provide more recent collections of Lepechinelloides karii with a total of 95 specimens known from six stations in the Iceland Basin. Depth range: 2150 to 2750 m. Distribution: Iceland Basin (Thurston, 1980; present study) (Fig. 9B, Tables 1, 2)., Published as part of L��rz, Anne-Nina, Brix, Saskia, Ja��d��ewska, Anna M. & Hughes, Lauren Elizabeth, 2020, Diversity and distribution of North Atlantic Lepechinellidae (Amphipoda: Crustacea), pp. 1095-1122 in Zoological Journal of the Linnean Society 190 on page 1118, DOI: 10.1093/zoolinnean/zlaa024, http://zenodo.org/record/5722220, {"references":["Thurston MH. 1980. Abyssal benthic Amphipoda (Crustacea) from the East Iceland Basin 2. Lepechinella and an allied new genus. Bulletin British Museum of Natural History (Zoology) 38: 69 - 87.","Barnard JL, Karaman G. 1991. The families and genera of marine gammaridean Amphipoda (except marine gammaroids). Records of the Australian Museum 13: 1 - 866."]}