Cognateosymtes Labay, 2018

Labay, Vjacheslav S., 2022, Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island (Far East of Russia). II. Subfamily Eosymtinae Bousfield & Hendrycks, 1994, Zootaxa 5125 (5), pp. 547-562 : 558-561

Genus Cognateosymtes Labay, 2018

Cognateosymtes Labay, 2018: 221 .

Type species. Cognateosymtes serraticoxae Labay, 2018 .

Species. Cognateosymtes serraticoxae Labay, 2018 .

Diagnosis (from Labay 2018) ( Figs. 1c , 2c, f, i, l, o , 3f, g, h ). Body medium, smooth. Urosome segment 2 not occluded dorsally. Rostrum short. Anterior head lobe truncated. Eyes large, subreniform. Antenna 1, anterodistal peduncular process strong.

Upper lip, apical lobes slightly asymmetric. Lower lip regular, inner lobes weak, narrowly sloped. Mandible, spine-row short, with 6 pectinate blades; left lacinia 6 dentate, right lacinia blade-like. Maxilla 2, inner plate with 2 strong submarginal and subapical setae. Maxilliped, outer plate high, with one strong apical seta only and straight inner cutting edge; inner plate with 3 small apical spiniform setae and with 3 rows of 2–4 short stout plumose setae; palp segment 3 not produced distally, dactyl slender, slightly curved, not pectinated.

Coxal plates 1–4 medium, little deeper than pereon, increasing posteriorly; hind corners of coxae 1–2 each with 3–5 small cusps. Gnathopods 1 & 2 similar in form, carpus longer than ¾ length of propodus, palmar margin short, oblique, smoothly continuous with densely setose, elongate posterior margin. Pereopods 3 and 4 slender. Pereopods 5–7 unequal in form; pereopod 5 the shortest; basis broadened, rounded behind, hind margin weakly serrate.

Epimeral plates 1–3, hind corners acuminate, not produced, posterior margins slightly sinuous. Uropod 3 slender, outer ramus not more than 2/3 the length of the inner ramus.

Telson linguiform, apex subtruncate, with paired prominent notch; telson keeled proximally.

Marsupial plates are leaf-like, broad, with short setae.

Distribution. The shelf of Sakhalin Island, Sea of Japan, Sea of Okhotsk ( Labay 2018; recent data) ( Fig. 11 ).

Figures

FIGURE 1. Eosymtinae Bousfield & Hendrycks, 1994, lateral view: a—Eosymtes minutus Bousfield and Hendrycks, 1994 (from Bousfield and Hendrycks 1994: fig. 7), b—Eosymtes magnumoculis sp. nov., c—Cognateosymtes serraticoxae Labay, 2018 (from Labay 2018: fig. 2a)

FIGURE 2. Eosymtinae Bousfield & Hendrycks, 1994: a–c—peduncle of antenna 1; d–f—maxilla 2; g–i—palp of maxilliped; j–l—coxal plates 1–3 posteroventrally; m, n, o—propodus and dactylus of pereopods 3–7; a, d, g, j, m—Eosymtes minutus Bousfield and Hendrycks, 1994 (from Bousfield and Hendrycks 1994), b, e, h, k, n—Eosymtes magnumoculis sp. nov., c, f, i, l, o—Cognateosymtes serraticoxae Labay, 2018 (from Labay 2018)

FIGURE 3. Eosymtinae Bousfield & Hendrycks, 1994: a—urosome segments 1–3; c, f—uropod 1; d, g—uropod 2; b, e, h—uropod 3; a, b—Eosymtes minutus Bousfield and Hendrycks, 1994 (modified from Bousfield and Hendrycks 1994), c, d, e—Eosymtes magnumoculis sp. nov., f, g, h—Cognateosymtes serraticoxae Labay, 2018 (from Labay 2018)

FIGURE 11. Distribution of Eosymtinae species in Far Eastern Region