Neopleustes pulchellus asiaticus, Labay, 2021

Labay, Vjacheslav S., 2021, Review of amphipods of the family Pleustidae Buchholz, 1874 (Crustacea Amphipoda) from the coastal waters of Sakhalin Island (Far East of Russia). I. Subfamily Neopleustinae Bousfield & Hendrycks, 1994, Zootaxa 4974 (2), pp. 267-306 : 297-300

Neopleustes pulchellus asiaticus ssp. nov.

Figures 1i , 2f,m,t ,ab, 3e, 4i, 5h, 19–21, 22

Diagnosis. Male (11.1 mm). Body, pereon segments 1–3 without carination, pereon segment 4 with weak carination, strongly carinated posteriorly from pereon segment 5 to pleon segment 2, pleon segment 3 with low tooth dorsally. Head, pereonal and pleonal segments with submedial and sublateral single specific pappose setae dorsally.

Head without anterodorsal crest. Rostrum short, about 0.2 times as long as peduncular segment 1 of antenna 1, apex rounded; anterior head lobe rounded, lateral cephalic lobe deeply recessed sinus, anteroventral corner acute. Eye large, subrounded, pigmented, yellow-brown. Antenna 1 destructed; peduncular segment 1 elongate and strong, 1.5 times as long as segment 2. Antenna 2 destructed; peduncular segment 4 elongate and strong, as long as segments 1, 2 and 3 together, segment 3 with strong spine-like seta at the anterodistal angle, segment 4 with short process on inner and outer distal margins each.

Upper lip apically bilobate and asymmetrical. Lower lip, outer lobes suboval, widely spread. Mandible, molar weak, tubercle, bare, without a medial molar seta; incisor margins with 8–9 teeth; left lacinia 9-dentate, right lacinia absent; accessory spine rows with 9 raker setae; palp large; palp segment 3 is 1.5 times as long as segment 2, inner margin in the distal 3/4 lined with strong pectinate D setae, apex with 3 long and strong pectinate E setae; segment 2, inner margin with a rare row of pectinate setae; segment 1 without setae. Maxilla 1, inner plate with two plumose apical setae; outer plate with 9 slender pectinate setae (spine-like setae); palp extending beyond outer plate, apex subtruncate, with a row of 5 stout setae ( Watling, 1989: type IIA3) and with a subapical row of 8 thin setae. Maxilla 2, inner plate slightly shorter and broader than outer plate; inner margin with two strong plumose setae. Maxilliped, inner plate very short, not reaching the basal article of palp, apex semicircular, with 3 button setae ( Watling, 1989: type IIA5) and with two slender setae at the outer part; outer plate short, reaching about 0.15x length of palp segment 2, apex narrowly subtruncate; palp narrow, segment 2 0.87 times as long as segment 3, segment 3 with few strong plumose setae in the distal part of inner margin; dactylus slender, 1.5 times shorter than palp segment 3, the distal process of palp segment 3 is not conspicuous.

Coxal plates 1–3 posteroventrally multi-cuspate, lower margins with central ventral rounded angle; coxal plate 4 much broader, deeply excavated posteroproximally, with rounded angle below; coxal plates 5–6 broadly posterolobate, posteriorly roundly subquadrate, coxal plate 7 semicircular. Coxal gills relatively small, sac-like.

Pereopods 1 and 2 (gnathopods 1 and 2) small, weakly subchelate, subsimilar. Pereopod 1 linear, basis with rare anterior setae, carpus long, about 0.85 times as long as propodus, posterior lobe broad, shallow, with two specific plumose setae distally; propodus narrow, palm oblique, with small mid-palmar tooth, palmar angle with one transverse cluster of 4 or 5 spine-like setae; posterior margin with 3 groups of setae and with two single spine-like setae. Pereopod 2, basis long, linear, merus with posterodistal tooth, carpus long, about 0.65 times as long as propodus, carpal lobe as in pereopod 1, with 3 specific plumose setae distally, palmar margin oblique, with medial tooth and with 2 clusters of strong posterodistal spineformes setae, posterior margin with 4 or 5 transverse clusters of setae. Pereopods 3 and 4 destructed; basis linear, with short setae along anterior and posterior margins; merus anterodistally produced, acute, with 6 or 7 stout spineformes setae along posterior margin. Pereopods 5–7 destructed, closely homopodous in form and size; bases with posterior rounded wing, serrated posteriorly; merus posterodistally produced, acute, anterior margin with 6 groups of strong spine-like setae, posterior margin with 4 groups of cuspidate setae.

Epimeral plates 1–3, lower margin with short spine-like setae; posteroventral corners with process, the largest in plate 2; posterior margins minutely serrated in plates 2 and 3. Pleopods regular, coupling basis of inner ramus with 4 (pleopods 1 and 2) or 5 (pleopod 3) specific stout two-pointed plumose setae.

Uropod 1, peduncle slightly shorter than inner ramus; outer ramus the shorter; margins of peduncle and rami with serially arranged short spine-like setae. Uropod 2, inner ramus 1.6 times as long as peduncle, outer ramus the shorter, 0.72 times as long as inner. Uropod 3, inner ramus 3 times as long as peduncle, with a row of 7 small spineshaped setae along lateral and medial margins each, with acute and non-setae apex; outer ramus about 0.5 times as long as inner; outer ramus with a row of 7 small spine-shaped setae along lateral and medial margins each, with acute and non-setae apex. Telson linguiform, apically acute, length about 2.16x width, with proximal ventral keel, without lateral paired short setae.

Female: similar to male.

Type material. Holotype, male, 11.1 mm, Х 53868 /Cr-2413, Sea of Okhotsk , Far East of Russia (52°28.9447’ N 143°57.1337’ E, 72 m), sands, 11 August 2018 . Paratype: 1 female, 7.6 mm, Х 53869 /Cr-2414, with same data as holotype .

Type locality. The north-east shelf of Sakhalin Island , Sea of Okhotsk, Far East of Russia (52°28.9447’ N 143°57.1337’ E, 72 m) .

Etymology. Named after the type locality near the Asian coast of Pacific Ocean. The name is masculine in gender.

Ecology: Neopleustes pulchellus asiaticus was found at the depth of 72 m on sands in the layer of constant low temperature (-1.2—+0.5°C). Females with developed marsupium were found in August.

Distribution: The shelf of north-eastern Sakhalin Island.

Remarks. Neopleustes pulchellus asiaticus ssp. nov. is morphologically identical to the nominant subspecies Neopleustes pulchellus (Krøyer, 1846) ( Hendrycks & Bousfield 2004; Krøyer 1846; G. Sars 1895). Neopleustes pulchellus asiaticus differs from N. pulchellus pulchellus by the presence of submedial and sublateral long pappose single setae dorsally on the head, pereonal and pleonal segments ( Figs. 1h, 1i ). In N. pulchellus asiaticus the lower margin of coxal plates 1 and 2 is with subquadrate central ventral angle; in N. pulchellus pulchellus the lower margin of coxal plates 1 and 2 is with acute central ventral angle ( Figs. 4h, i , 5g, h ).). Postero-ventral process of epimeral plate 2 is the largest in N. pulchellus asiaticus ; in N. pulchellus pulchellus the postero-ventral process of epimeral plates 2 and 3 is subequal.

Figures

FIGURE 1. Neopleustinae Bousfield & Hendrycks, 1994, lateral view: a—Neopleustes boecki boecki (Hansen, 1888) (from Sars 1895: pl. 122), b—N. boecki pacifica ssp. nov., c—N. carinatus Margulis, 1963 (original image by author), d—N. columbianus Hendrycks & Bousfield, 2004 (from Hendrycks & Bousfield 2004: fig. 27), e—N. euacanthoides Gurjanova, 1972 (modified from Gurjanova 1972: fig. 18), f—N. euacanthus (G. Sars, 1876) (modified from Sars 1885: Pl. 14), g—N. kussakini (Budnikova, 1995) (modified from Budnikova 1995), h—N. pulchellus pulchellus (Krøyer, 1846) (from Sars 1895: pl. 122), i—N. pulchellus asiaticus ssp. nov., j—Shoemakeroides cornigerus (Shoemaker, 1964) (modified from Shoemaker 1964: fig. 9), k—Sh. gagarae (Gurjanova, 1972) (from Gurjanova 1972: fig. 16), l—Hendrycksopleustes neimanii sp. nov.

FIGURE 2. Neopleustinae Bousfield & Hendrycks, 1994, mouthparts: a–o—mandible; p–w—maxilla 1; x–ae—maxilla 2; a—Neopleustes boecki boecki (Hansen, 1888) (from Sars 1895: pl. 122), b, i, p, x—N. boecki pacifica ssp. nov., c, j, q, y—N. carinatus Margulis, 1963 (original image by author), d, k, r, z—N. columbianus Hendrycks & Bousfield, 2004 (from Hendrycks & Bousfield 2004: fig. 27), e, l, s, aa—N. pulchellus pulchellus (Krøyer, 1846) (from Sars 1895: pl. 122), f, m, t, ab—N. pulchellus asiaticus ssp. nov., u, ac—Shoemakeroides cornigerus (Shoemaker, 1964) (from Hendrycks & Bousfield 2004: fig. 30), g, m, v, ad—Sh. gagarae (Gurjanova, 1972) (from Gurjanova 1972: fig. 16), h, n, w, ae—Hendrycksopleustes neimanii sp. nov.

FIGURE 4. Neopleustinae Bousfield & Hendrycks, 1994, pereopod 1 (gnathopod 1): a—Neopleustes boecki boecki (Hansen, 1888) (from Sars 1895: pl. 122), b—N. boecki pacifica ssp. nov., c—N. carinatus Margulis, 1963 (original image by author), d—N. columbianus Hendrycks & Bousfield, 2004 (from Hendrycks & Bousfield 2004: fig. 27), e—N. euacanthoides Gurjanova, 1972 (modified from Gurjanova 1972: fig. 19), f—N. euacanthus (G. Sars, 1876) (modified from Sars 1885: Pl. 14), g—N. kussakini (Budnikova, 1995) (modified from Budnikova 1995), h—N. pulchellus pulchellus (Krøyer, 1846) (from Sars 1895: pl. 122), i—N. pulchellus asiaticus ssp. nov., j—Shoemakeroides cornigerus (Shoemaker, 1964) (modified from Shoemaker 1964: fig. 9), k—Sh. gagarae (Gurjanova, 1972) (from Gurjanova 1972: fig. 17), l—Hendrycksopleustes neimanii sp. nov.

FIGURE 5. Neopleustinae Bousfield & Hendrycks, 1994, pereopod 2 (gnathopod 2): a—Neopleustes boecki boecki (Hansen, 1888) (from Sars 1895: pl. 122), b—N. boecki pacifica ssp. nov., c—N. carinatus Margulis, 1963 (original image by author), d—N. columbianus Hendrycks & Bousfield, 2004 (from Hendrycks & Bousfield 2004: fig. 27), e—N. euacanthoides Gurjanova, 1972 (modified from Gurjanova 1972: fig. 19), f—N. kussakini (Budnikova, 1995) (modified from Budnikova 1995), g—N. pulchellus pulchellus (Krøyer, 1846) (from Sars 1895: pl. 122), h—N. pulchellus asiaticus ssp. nov., i—Shoemakeroides cornigerus (Shoemaker, 1964) (modified from Shoemaker 1964: fig. 9), j—Sh. gagarae (Gurjanova, 1972) (from Gurjanova 1972: fig. 17), k—Hendrycksopleustes neimanii sp. nov.