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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. |
