Hendrycksopleustes, 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 : 274-277

Genus Hendrycksopleustes gen. nov.

Figures 1l , 2h, n, w , ae, 3h, 4l, 5k, 6–11

Type species. Hendrycksopleustes neimanii sp. nov.

Species. Hendrycksopleustes neimanii sp. nov. from the shelf of north-eastern Sakhalin Island ( Sea of Okhotsk ) .

Diagnosis. Body strongly carinated dorsally from pereon segment 6 to pleon segment 2, pleon segment 3 with low ridge. Urosome segment 2 not occluded dorsally. Head without anterodorsal crest. Rostrum short. Anterior head lobe subqadrate. Eyes medium, ellipsoid. Antenna 1 much longer than antenna 2; segments 1 and 2 long, without anterodistal peduncular process and with small posterodistal peduncular process; accessory flagellum minute, scalelike. Antenna 2, peduncular segments 4 and 5 long, subequal, with apical setae only.

Upper lip notched apically, lobes slightly asymmetric. Lower lip, outer lobes rounded, steeply angular, widely separated by flat inner lobes. Mandible, molar small, conical, with small conical wart at the axis, and with microsetae, without triturating surface; left lacinia mobilis 10-dentate, right lacinia lacking; raker setae 15–16, slender; incisors 8-dentate; palp segment 3 with 12 D setae and with 4 medium length E setae. Maxilla 1, inner plate with 1–2 setae, palp with an apical row of 5–7 stout conical setae and with subapical row of 5–6 thin setae. Maxilla 2, inner plate with long subapical inner marginal seta and with numerous apical setae. Maxilliped, inner plate broadened, with 5 button spineformes setae; outer plate short; palp large, segments 1–3 broadened, segment 4 slender, slightly cirved.

Coxal plates 1–4 medium, strongly increasing in depth from 1 to 3. Coxal plate 1 hatched-shaped. Coxal plates 2 and 3 rounded distally. Hind corners of coxae 1–3 each with 2 or 3 small cusps. Coxa 5 and 6 posterolobate.

Pereopods 1 and 2 (gnathopods 1 and 2) powerful, similar in form and size, not sexually dimorphic; carpus short, with distinct narrow carpal lobe; propodus long, inflated; palmar margin long, vertical; posterior margin indistinct; dactylus long, but shorter than palmar margin.

Pereopods 3 and 4 slender, medium long, dactylus medium in length. Pereopods 5–7, basis broadened, rounded behind, hind margin minutely serrate.

Pleon plates 1–3, hind corners produced, acuminate. Uropod 1, peduncle with distolateral spine, peduncle about as long as inner ramus, outer ramus slightly shorter. Uropod 2, outer ramus distinctly shorter. Uropod 3 slender, outer ramus not more than 3/5 the length of inner ramus.

Telson linguiform, longer than wide, keeled slightly proximally, paired notch and setae prominent, lateral margins with few short setae.

Marsupial plates 2–4 broad, with long setae; plate 5 narrow.

Without sexual dimorphism.

Distribution. The shelf of north-eastern Sakhalin Island, Sea of Okhotsk.

Relationships: Hendrycksopleustes gen. nov. conforms essentially with the diagnosis of the subfamily Neopleustinae in the dorsally carinated body, strong peduncle of antenna 1, by the structure of mouthparts, especially of the mandible, by the hatched-shaped coxal plate 1. It differs mainly in the short rostrum, distal process on segment 3 of the palp of maxilliped indistinct, pereopods 1 and 2 (gnathopods 1 and 2) powerful, similar in form shape and size.

Hendrycksopleustes differs from the genus Neopleustes Stebbing, 1906 in the short rostrum, in the setacea of inner plate of maxilla 1 (2 setae mainly in Hendrycksopleustes and single seta in Neopleustes ), and large gnathopods, in which propods are inflated and subsimilar in form, and the carpus shortened, with narrow carpal lobe.

Hendrycksopleustes differs from Shoemakeroides Hendrycks & Bousfield, 2004 by the following combination of character states: inner plate of maxilla 1 with 2 setae mainly; propodus of gnathopods 1 and 2 large, inflated, subsimilar in size and forms, carpus shortened, with narrow carpal lobe; basis of pereopods 5–7 broadened, rounded behind.

Etymology: The genus Hendrycksopleustes is named in honor of the famous Canadian carcinologist E.A. Hendrycks, and with the genus name Pleustes . The name is masculine in gender.

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.