Vinogradovopleustes punctatum, Labay, 2018

Labay, Vjacheslav S., 2018, Vinogradovopleustes punctatum, new genus, new species, a pleustid amphipod from the Okhotsk Sea (Crustacea: Amphipoda: Gammaridea: Pleustidae: Pleusymtinae), Zootaxa 4392 (1), pp. 159-168 : 161-167

Vinogradovopleustes punctatum sp. nov.

Figures 1–7

Diagnosis. With the characters of the genus. Eyes large, subreniform. Body medium, inflated, carinated middorsally on pereon, pleon and urosome. The whole surface of the body and coxal plates with a large-dotted sculpture. Rostrum elongate, about as long as peduncular segment 1 of antenna 1, apex acute. Antenna 1, segment 2 of peduncle with small anterodistal process, accessory flagellum minute, scale-like. Lower lip, outer lobes rounded not widely spread. Mandible, molar strongly triturative; palp segment 3 subequal to segment 2 in length; segment 2, inner margin weakly setose; segment 1 without setae. Maxilla 1, inner plate with single plumose apical seta; outer plate with 9 strong pectinate setae (spine-like setae). Maxilliped, inner plate reaching base of palp; outer plate reaching about 0.5 x length of palp segment 2; palp segment 2 the longest; segment 3 narrower, slightly broadened medially; dactylus slender, curved, as long as palp segment 3. Coxal plate 1–3 very deep, plate 1 with concave anterior margin; coxa plate 4 much broader, deeply excavated posteroproximally; coxal plates 5–7 posterolobate, posteriorly subquadrate. Pereopod 1, palmar margin without medial tooth, with 3–4 clusters of posterodistal strong setae (spines). Pereopod 2 subequal; carpal lobe short, produced slightly forwards along posterior margin of propodus. Pereopods 5–7, dactylus medium, 0.75 times as long as propodus. Epimeral plate 3, posteroventral corner produced into a large tooth.

Type material. Holotype male (?), 8.5 mm, X 47110 Cr 2210, Okhotsk Sea, Far East of Russia (55°00'00''N 142°02'40''E, 130 m), silt and small pebble, V.Iu. Lalov, 27 August 2007 . Paratypes: 1 male (?), 8.5 mm, X 47111 Cr 2211, Okhotsk Sea, Far East of Russia (51°20'20''N 144°11'41''E, 170 m), silt and pebble, I.A. Scherbakov, 20 August 2014 .; 3 males (?), X 47112 Cr 2212, Okhotsk Sea, Far East of Russia (51°20'04''N 144°13'07''E, 170 m), silt and pebble, I.A. Scherbakov, 20 August 2014 .; 2 males (?) X 47113 Cr 2213, Okhotsk Sea, Far East of Russia (51°21'47''N 144°16'53''E, 200 m), silt, 11 September 2016 .

Type locality. The northern part of Okhotsk Sea, Far East of Russia (55°00'00''N 142°02'40''E, 130 m).

Description. Male? (8.5 mm). Vital body color is unknown; color in alcohol almost colourless, uniformly pale yellow. Body medium, inflated, carinated middorsally on pereon, pleon and urosome 1; urosome segment 2 occluded dorsally. Dorsal carination as in Mesopleustes abyssorum ( Stebbing, 1888) (Barnard & Karaman 1991; Bousfield & Hendrycks 1994; Stebbing 1888; Vinogradov 1994): thoracic segments carinate, dorsal carina of each thoracic segment pulled back, pleon segments 1 & 2 with dorsoposterior carina each, pleon segment 3 with pulled up middorsal carina, urosome segment 1 with small pulled up middorsal carina, urosome segment 2 occluded dorsally, urosome segment 3 without dorsal carina ( Fig. 2a ). The whole surface of the body and coxal plates with a large-pointed sculpture ( Figs. 2a , 5f, g ).

Head ( Fig. 2a ): slightly shorter than pereonites 1, 2 & 3 combined, rostrum about as long as peduncular segment 1 of antenna 1; eyes large, subreniform; anterior head lobe prominent, acute. Antenna 1 ( Fig. 2b ): medium length, nearly 40% of body length; flagellum bearing 30 articles; peduncle article 1 1.7 times longer the length of article 2, with a few simple setae at the distal corner of posterior margin, segments 1 & 2 with small anterodistal process each, article 3 0.5 times the length of article 2; accessory flagellum, scale-like. Antenna 2 ( Fig. 2c ): flagellum with 22 articles; peduncle articles 5 as long as article 4 length, articles 2, 3 combined subequal to article 4 or article 5 each; article 2 with long posterodistal protrusion which subequal to article 3 length. Labrum ( Fig. 2d ): apical lobes slightly asymmetric. Mandible ( Figs. 2e, f , 3a, b ): molar strong, columnar, with pavement-type grinding surface; palp 3-articulate, article 1 of palp without setae, palp segment 2 with a rare row of simple setae (D-2 setae), palp segment 3 slightly curved, with posterior row of 5–6 specific plumose D3-setae, with group of 3 plumose distal E3-setae and one simple E-3 seta. Labium ( Fig. 3c ): inner lobes weak, narrowly sloped; outer lobes rounded at distal margin. Maxilla 1 ( Fig. 3d ): inner plate ovate, with 1 plumose seta apically; outer plate elongate, apically with 2 rows of 9 pectinate strong setae; palp 2-articulate, apical margin of article 2 with 7 stout spine-like setae and with a row of 7 subapical setae. Maxilla 2 ( Fig. 3e ): inner plate with one strong plumose seta on the inner margin. Maxilliped ( Fig. 3f ): inner plates small, fully cleft, short, broad, with short conate setae (Watling type II.A4) ( Watling 1989) and with 2 simple setae at the truncated apex; outer plate elongated, rounded apically, inner margin setose, apex with 3 strong setae; palp 4-articulate; article 4 (dactylus) slender, curved.

Pereon: Pereopod 1 (gnathopod 1) ( Fig. 4a, b, c ): coxa deep, with posterior tooth and with 3–5 small posterodistal cusps; basis straight; merus with one simple seta at the border of 2/3 of posterior margin, distal margin with a dense row of numerous setae; carpus 0.6 times as long as propodus, posterior lobe shallow, with 2 groups of simple setae, with posterodistal tuft of numerous simple setae + 2 plumose setae; propodus suboval, 2.2 as long as wide, palmar margin smoothly oblique, 1.6 times as long as posterior margin, without medial tooth, with 3 clusters of posterodistal robust setae associated with a few setae; dactylus shorter than palmar margin of propodus, curved. Pereopod 2 (gnathopod 2) ( Fig. 4d, e ): coxa deep, with posterior tooth and with 3–5 small posterodistal cusps; basis slightly broadened; merus with a few simple setae at the border of 2/3 of posterior margin, distal margin truncated, with a few simple setae; carpus medium, 0.67 times as long as propodus, carpal lobe short, produced slightly forwards along posterior margin of propodus; propodus suboval, 1.8 as long as wide, with 2 groups of simple setae at the posterior margin, palmar margin smoothly oblique, 1.9 times as long as posterior margin, without medial tooth, with 4 clusters of posterodistal strong setae (spines); dactylus as in pereopod 1. Pereopod 3 ( Fig. 5a ): coxa deep, 2.2 times as long as wide, rounded anterodistally, with posterior tooth and with 1–3 small posterodistal cusps; leg rather slender; basis linear; merus as long as carpus, produced slightly forwards along anterior margin of carpus; propodus long, 1.15 times as long as carpus; dactylus medium, 0.7–0.8 times as long as propodus. Pereopod 4 ( Fig. 5b, c ): coxa as long as wide, narrowed and rounded distally, with deep excavation posteromarginally; basis to dactylus as for pereopod 3. Pereopod 5 ( Fig. 5d, e ): coxa posterolobate, with rounded front margin, posteriorly subquadrate, posterior lobe pulled back and down, with lateral posterior protrusion (stopper); basis linear, without posterior wing; merus produced slightly forwards along posterior margin of carpus, narrow; carpus 0.92 times as long as merus; propodus linear, more narrow and 1.2 times as long as carpus; dactylus medium, 0.72 times as long as propodus, weakly curved, slender. Pereopod 6 ( Figs. 5h , 6a ): coxa posterolobate, with rounded ventral front margin, posterior lobe pulled back and down, proximally with produced angulated posterior margin; basis with narrow posterior lobe, width 0.43–0.50 times as length, posterior margin straight, with numerous small notches; merus slightly produced forwards along posterior margin of carpus; carpus 0.86 times as long as merus; propodus linear, 1.3 times as long as carpus; dactylus medium, 0.75 times as long as propodus. Pereopod 7 ( Fig. 6b, c, d ): coxa antero- and posterolobate, anterior lobe small, subquadrate, posterior lobe subquadrate, width subequal to length; basis broadened, with distinct posterior lobe, posterodistal corner rounded, width 0.73–0.75 times as length, posterior margin convex, crenulated; ischium; merus, carpus, propodus and dactylus as in pereopod 6. Coxal gills 2–6. Coxal gill 6 is smaller than gill 5.

Pleon: Epimeral plates: ( Fig. 6e, f, g ) plates 1–2, posterior corners with small tooth each; plate 1 rounded triangular; plate 2, ventral margins convex; plate 3, posteroventral corner produced into a large tooth, ventral margin convex. Pleopods: ( Fig. 6h, i , 7a–c ) normal; inner ramus slightly shorter than outer ramus, coupling basis of inner ramus with 3–4 specific stout two-pointed plumose setae along inner margin. Uropod 1: ( Fig. 7d ) peduncle 1.16 times as long as outer ramus, armed with a large robust seta at distal end of outer margin. Uropod 2: ( Fig. 7e ) inner ramus 1.69 times longer than peduncle, outer ramus 0.79 times as long as inner. Uropod 3: ( Fig. 7f ) inner ramus 2 times longer than peduncle, with acute and non-spinose apex; outer ramus about 0.73 times as long as inner; outer ramus with a row of 3–4 small spine-shaped setae along lateral and medial margins each, with acute and non-spinose apex. Telson: ( Fig. 7g ) elongate, linguiform, apically rounded, length about 1.5x width, with median ventral keel, plumose marginal penicillate setae are absent.

Female: unknown.

Variation. It is not marked.

Etymology. Species name punctatum is based on a Latin word punctatum (dotty). The name is masculine in gender.

Ecology. Vinogradovopleustes punctatum was found in the depth interval 130–200 m on silt-gravel and silt bottoms.

Distribution. The northern part of Okhotsk Sea, the shelf of northern and north-eastern Sakhalin Island ( Fig. 1 ).

Figures

FIGURE 1. Distribution of Vinogradovopleustes punctatum sp. nov. on the shelf of the Okhotsk Sea.

FIGURE 2. Vinogradovopleustes punctatum sp. nov., holotype, male, 8.5 mm, a, b, c, e, f; paratype, male, d: a—lateral view, b—antenna 1, c—antenna 2, d—upper lip, e, f—left mandibule; scale: a, b, c, e—1 mm; d—0.1 mm.

FIGURE 3. Vinogradovopleustes punctatum sp. nov., holotype, male, 8.5 mm, a, d, e, f; paratype, male, 8.5 mm, b, c: a, bright mandible, c—lower lips, d—maxilla 1, e—maxilla 2, f—maxilliped; scale: a, f—1 mm; b, c, d, e—0.1 mm.

FIGURE 4. Vinogradovopleustes punctatum sp. nov., holotype, male, 8.5 mm, a, c, d; e; paratype, male, 8.5 mm, b: a, b—coxa 1; c—pereopod 1, d—coxa 2, e—pereopod 2; scale: b, c, e,—1 mm; a, d—0.1 mm.

FIGURE 5. Vinogradovopleustes punctatum sp. nov., holotype, male, 8.5 mm, a, b, c, d, h; paratype, male, 8.5 mm, e, f, g: apereopod 3, b—coxa 4, c—pereopod 4, d—pereopod 5, e—coxa 5, f, g—sculpture of surface, h—pereopod 6; scale: a, b, c, d, e, h—1 mm.

FIGURE 6. Vinogradovopleustes punctatum sp. nov., holotype, male, 8.5 mm, b, e, f, g, h, i; paratype, male, 8.5 mm, a, c, d: a—pereopod 6, b, d—pereopod 7, c—coxa 7, e, f, g—epimer 1–3, h—pleopod 2, i—coupling spines of pleopod 2; scale: a, b, d, e, f, g, h—1 mm; c—0.1 mm.

FIGURE 7. Vinogradovopleustes punctatum sp. nov., holotype, male, 8.5 mm: a, b, c—coupling setae of pleopods 1, 2 and 3, d—uropod 1, e—uropod 2, f—uropod 3, g—telson; scale: d, e, f—1 mm; g—0.1 mm.