Cyproidea okinawensis Ariyama, 2016, sp. nov.
Creators: name: Ariyama, Hiroyuki
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Cyproideidae
Cyproidea
Cyproidea okinawensis

description: Cyproidea okinawensis sp. nov.
[Japanese name: Okinawa-hoteiyokoebi, new] (Figs 7–11)
Material examined. Holotype: female (OMNH-Ar-9951), 5.0 mm, point "Red beach", Kin Bay, Kin Town, Okinawa Prefecture, 26°26'24"N, 127°54'36"E, 3 m in depth, sandy bottom, using SCUBA, 13 December 2014, coll. N. Shirakawa. Paratypes: 2 ovigerous females (OMNH-Ar-9952–9953), 4.5, 4.3 mm, same data as holotype; 2 ovigerous females (OMNH-Ar-9954–9955), 4.2, 4.0 mm, 5 m, 6 December 2014, other data same as holotype.
Description. Female [based on holotype, 5.0 mm (OMNH-Ar-9951), paratype, 4.5 mm (OMNH-Ar-9952) for lower lip, and paratype, 4.3 mm (OMNH-Ar-9953) for mandibles]. Body (Fig. 7) oval; head longer than pereonite 1, eyes relatively small, diameter 35% length of head; pereonites 4–5 long, posteroventral corners of pereonites 5– 7 protruded; coxa 5 barely reaching posteroventral corner of pereonite 6; pleonites 1–3 each with dorsolateral ridge extending to urosomite 1; urosome slender.
Antenna 1 (Fig. 8 A, A1) short, with ratio of lengths of peduncular articles 1–3 1:1.4:0.6, tooth of article 2 occupying quarter of whole length; accessory flagellum vestigial, with 3 setae; primary flagellum with 7 articles, articles 2, 3, 5, 6 each with 1 aesthetasc at distal end, respectively. Antenna 2 (Fig. 8 B) short, with ratio of lengths of peduncular articles 3–5 1:1.8:1.5; flagellum with 3 articles.
Upper lip (Fig. 8 C), ventrolateral margins with short setae. Mandible (Fig. 8 D, D1, E, E1), incisor bearing 6–7 cusps, left lacinia mobilis fan-shaped, distal margin serrated, right lacinia mobilis lacking, number of both accessory blades 6 (paratype, 4.3 mm) or 10 (holotype, 5.0 mm); palp article length ratio 1:1.3: 1.1 in right, article 2 without setae, tip of article 3 with a long seta. Lower lip (Fig. 8 F) wide; inner lobes indistinct; anteromedial surfaces of outer lobes setose, each with 1 round and 1 truncate projections on corner, mandibular processes small. Maxilla 1 (Fig. 8 G, G1 – 2), inner plate rounded, with 4 setae on tip; mediodistal corner of outer plate projected, distal margin with 7 robust setae, medial margin bearing 5 robust setae; distal end of palp projected in middle, with 3 minutely-serrated robust setae and 3 robust setae (+1 additional spine in left). Maxilla 2 (Fig. 8 H), inner plate shorter and wider than outer, terminal ends of both plates each with a few setae, dorsodistal surfaces of both plates setose. Maxilliped (Fig. 8 I, I1 – 2), inner plate truncate, mediodistal corner with 2 robust setae dorsally; outer plate with 2 distal robust setae, mediodistal margin serrated; palp articles 1 – 2 with 3 and 6 setae, respectively, article 3 covered with short setae dorsally, article 4 slender.
Gnathopod 1 (Fig. 9 A, A1), coxa roundish pentagonal; basis long, slightly curved posteriorly; posterodistal corner of ischium not projected; merus short; carpus long, posterodistal corner slightly protruded, bearing 3 long setae, posteromedial surface covered with thin setae; propodus long, about 1.5 times as long as carpus, palm with many acute denticles, anteromedial surface covered with thin setae; dactylus long, slightly curved, posteroproximal margin bearing 1 long and 6 short acute spines. Gnathopod 2 (Fig. 9 B, B1) stouter than gnathopod 1; coxa trapezoidal; posterodistal corner of ischium strongly projected, with several setae; merus short; posterodistal projection of carpus longer than carpus proper, bearing 4 medial setae, posteromedial surface covered with thin setae; propodus relatively wide, palm with many blunt denticles; dactylus strongly flexed at a point of one fourth, gradually narrower, posteroproximal margin bearing 10 denticles.
Pereopod 3 (Fig. 9 C), coxa triangular, anterior margin rounded, posterior margin slightly concave, posteroproximal corner with small projection, posteroventral corner with small medial hollow; basis and merus – propodus long. Pereopod 4 (Fig. 9 D), coxa extremely wide, swollen posteriorly, anterior margin slightly convex, with small projection on anteroventral corner, ventral margin also slightly convex, posteroproximal corner a little projected; basis and merus – propodus long. Pereopod 5 (Fig. 9 E, E1), coxa lanceolate, width about 2.8 times of length, anterior margin with small hollow, posterior end pointed; basis and merus – propodus long. Pereopod 6 (Fig. 9 F, F1) slightly shorter than pereopod 5; coxa roundish trapezoidal; basis and merus – propodus long. Pereopod 7 (Fig. 9 G) almost same length as pereopod 6; coxa roundish trapezoidal; basis and merus – propodus long.
Pleonal epimera (Fig. 10 A), each with oblique lateral ridge (short in epimeron 1); epimera 1–2 projected bluntly and epimeron 3 rounded each on posteroventral corner; all ventral margins bare. Pleopods (Fig. 10 B – D), pleopod 3 a little shorter than pleopods 1–2; peduncles of pleopods 2–3 bearing a few setae; inner and outer rami with 10, 9, 9 and 11, 11, 12 articles in pleopods 1 – 3, respectively. Uropods (Fig. 10 E – G), peduncle and both rami without robust setae, but bearing minute denticles; peduncle of uropod 1 long, both rami about 0.8 times as long as peduncle; uropod 2 86% length of uropod 1, both rami 94% as long as peduncle; uropod 3 short, 64% length of uropod 1, peduncle relatively short, inner ramus about 1.3 times as long as peduncle, outer ramus almost same length as peduncle. Telson (Fig. 10 G) ovoid, breadth about 0.6 times of length, without setae. Male unknown.
Coloration in life (Fig. 11). Eyes red; dorsolateral surfaces from head to pereonite 7 with many brown and white pigments, ventral surfaces of pereonites and whole of pleonite 1 white; anteroproximal part of coxa 3 white, with several red pigments, anteroproximal and anteroventral parts of coxa 4 white, posteroproximal part of coxa 4 with black and red pigments.
Etymology. Referring to the type locality.
Remarks. Cyproidea okinawensis sp. nov. has the gnathopod 2 with both of a posterodistally-projected ischium and a long flexed dactylus. Only two species of Cyproidea, C. liodactyla and C. robusta Ren, 2006 collected from China, have such a gnathopod 2. However, this new species is different from C. liodactyla in the smaller eyes, the narrower coxa 5 and the coloration. Although the coloration of C. robusta resembles (milk white, with points of darkish-brown pigments), this species can be distinguished from C. robusta by the ovoid telson (pointed in C. robusta).
Distribution. Japan: only Kin Town in Okinawa Prefecture (Fig. 1).
Habitat. Sandy bottom, 3–5 m in depth.
description: Published as part of Ariyama, Hiroyuki, 2016, Five species of the family Cyproideidae (Crustacea: Amphipoda) from Japan, with the description of a new genus and two new species, pp. 301-331 in Zootaxa 4097 (3) on pages 309-313, DOI: 10.11646/zootaxa.4097.3.1, http://zenodo.org/record/263937