Metacyproidea makie, Ariyama, Hiroyuki, 2016

Ariyama, Hiroyuki, 2016, Five species of the family Cyproideidae (Crustacea: Amphipoda) from Japan, with the description of a new genus and two new species, Zootaxa 4097 (3), pp. 301-331 : 315-320

Metacyproidea makie sp. nov.

[Japanese name: Makie-hoteiyokoebi, new] ( Figs 12–16 )

Material examined. Holotype: female with larvae (OMNH-Ar-9956), 7.9 mm, point "Kyu-yaeneko", Hachijo Island, Tokyo Prefecture, 33°05'41"N, 139°46'14"E, 3 m in depth, on seaweeds, using SCUBA, 8 July 2012, coll. K. Tanaka. Paratypes: 3 ovigerous females and 1 female with larvae (OMNH-Ar-9957–9960), 6.9, 6.2, 5.7, 5.1 mm, same data as holotype.

Description. Female [based on holotype, 7.9 mm (OMNH-Ar-9956)]. Body ( Fig. 12 ) oval; head a little longer than pereonite 1, eyes medium-sized, diameter 44% 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. 13 A, A1) short, with ratio of lengths of peduncular articles 1–3 1:1.2:0.5, tooth of article 2 occupying quarter of whole length; accessory flagellum vestigial, with 4 setae; primary flagellum with 16 articles, articles 1–15 with 2, 1, 2, 3, 4, 2, 2, 2, 2, 2, 2, 2, 0, 1, 1 aesthetascs at each distal end. Antenna 2 ( Fig. 13 B) short, with ratio of lengths of peduncular articles 3–5 1:1.5:1.4; flagellum with 3 articles.

Upper lip ( Fig. 13 C) widely expanded anterodorsally, ventrolateral margins with short setae. Mandible ( Fig. 13 D, D1, E, E1), incisor bearing 9 cusps, left lacinia mobilis longish triangular, distal margin bearing 8 cusps, right lacinia mobilis lacking, number of accessory blades 16 in left and 18 in right; palp article length ratio 1:2.0: 1.6 in left and 1:1.8: 1.4 in right, dorsal margin of article 1 bearing many short setae, medial surfaces of articles 2–3 covered with short setae, tip of article 3 with 1 long seta. Lower lip ( Fig. 13 F), inner lobes distinct; anteromedial surfaces of outer lobes heavily setose, each with 1 truncate projection on corner, mandibular processes small. Maxilla 1 ( Fig. 13 G, G1), inner plate rounded, distal margin setose; mediodistal corner of outer plate acutely projected, distal margin with 7 robust setae, medial margin heavily setose; distal end of palp with 3 minutelyserrated robust setae and 3 robust setae, laterodiatal margin heavily setose. Maxilla 2 ( Fig. 13 H), inner plate longer and wider than outer, terminal ends of inner and outer plates with 4 and 2 thick setae, respectively, dorsal surfaces of both plates heavily setose. Maxilliped ( Fig. 13 I, I1 – 2), distal margin of inner plate setose, with 3 robust setae; outer plate setose laterally, with 3 distal robust setae; ventral surfaces and medial margins of palp articles 1 – 2 setose, mediodistal corner of article 3 with 1 plumose seta, articles 3 – 4 covered with short setae dorsally, article 4 slender.

Gnathopod 1 ( Fig. 14 A, A1–2), coxa trapezoidal, anterior margin with many short setae, ventral margin bearing 2 setae; basis long, distal half swollen anteriorly; ischium setose posteriorly, posterodistal corner not projected; merus short; carpus medium length, posteromedial surface covered with thin setae, posterodistal corner protruded, lateral and medial surfaces of tip bearing 6 and 2 long setae, respectively; propodus long, stout, about 1.4 times as long as carpus, palm with many short setae, anteromedial surface covered with thin setae; dactylus long, slightly curved, posterior margin without spines, medial surface bearing row of thin setae. Gnathopod 2 ( Fig. 14 B, B1), coxa trapezoidal, anteroventral corner produced, with a few short setae; oostegite long, distal margin with many long setae; ischium short, posterodistal corner strongly projected, with many setae; merus short; posterodistal projection of carpus longer than carpus proper, almost reaching posterodistal corner of propodus, medial surface bearing 1 robust short seta and 5 normal setae, posteromedial surface covered with thin setae; propodus relatively wide, palm with many blunt denticles; dactylus short, almost straight, gradually narrower, posterior margin smooth.

Pereopod 3 ( Fig. 14 C), coxa triangular, anterior margin rounded, posterior margin slightly concave, posteroproximal and posteroventral corners each with small projection; distal part of oostegite wide, margin with many setae; basis relatively long. Pereopod 4 ( Fig. 14 D), coxa extremely wide, swollen posteriorly, anterior margin slightly convex, with small hollow on anteroventral corner, ventral margin also slightly convex, posteroproximal corner a little projected; oostegite same as pereopod 3; basis relatively long. Pereopod 5 ( Fig. 14 E), coxa lanceolate, width about 3.1 times of length, anteroproximal corner slightly projected, middle anterior margin with small hollow, posterior end pointed; oostegite short, with 8 setae; basis and merus – propodus long. Pereopod 6 ( Fig. 14 F) shorter than pereopod 5; coxa parallelogramatic, width about twice of length; basis long. Pereopod 7 ( Fig. 14 G, G1) a little shorter than pereopod 6; coxa rhomboidal, short; basis long.

Pleonal epimera ( Fig. 15 A), epimera 1–2 each with oblique lateral ridge; posteroventral corners projected bluntly in epimeron 1, projected acutely in epimeron 2, and rounded in epimeron 3; all ventral margins bare. Pleopods ( Fig. 15 B – D), pleopod 3 a little shorter than pleopods 1–2; peduncles bearing several setae; inner and outer rami with 13, 13, 11 and 14, 16, 15 articles in pleopods 1 – 3, respectively. Uropods ( Fig. 15 E – G), peduncle and both rami without robust setae, but bearing minute denticles; peduncle of uropod 1 long, both rami 55% length of peduncle; uropod 2 about 0.8 times as long as uropod 1, both rami 63% length of peduncle; uropod 3 short, about 0.6 times as long as uropod 1, inner and outer rami 68% and 60% length of peduncle, respectively. Telson ( Fig. 15 G) longish trapezoidal, breadth about 0.6 times of length, distal end slightly hollowed in middle, lateral and distal margins without setae.

Male unknown.

Coloration in life ( Fig. 16 ). Head gold, eyes red; dorsal surfaces of pereonites with many white pigments, lateral surfaces of pereonites with many orange and several blue pigments on a brown background; coxae 3–4 similar to lateral surfaces, but with several large white marks.

Etymology. Referring to the coloration resembling makie, Japanese traditional craft.

Distribution. Japan: only Hachijo Island in Tokyo Prefecture ( Fig. 1 ). Habitat. On seaweeds, 3 m in depth.

Figures

FIGURE 1. Map showing collecting sites of the examined specimens.

FIGURE 12. Metacyproidea makie gen. et sp. nov. Holotype, female (OMNH-Ar- 9956), 7.9 mm. Habitus, lateral view.

FIGURE 13. Metacyproidea makie gen. et sp. nov. Holotype, female (OMNH-Ar- 9956), 7.9 mm. A, left antenna 1, lateral view; A 1, accessory flagellum of left antenna 1, medial view; B, left antenna 2, lateral view; C, upper lip, lateral view; D, left mandible, medial view; D 1, incisor, lacinia mobilis and accessory blades of left mandible, medial view; E, right mandible, medial view; E 1, incisor and accessory blades of right mandible, medial view; F, lower lip, ventral view; G, right maxilla 1, dorsal view; G 1, distal part of right maxilla 1, dorsal view, normal setae omitted; H, right maxilla 2, dorsal view; I, left maxilliped, ventral view; I 1, distal part of outer plate of left maxilliped, ventral view, normal setae omitted; I 2, distal part of inner plate of left maxilliped, ventral view, normal setae omitted. Scale: A – B, 0.5 mm; C – I, 0.43 mm; A 1, 0.25 mm; D 1, E 1, G 1, I 1 – 2, 0.215 mm.

FIGURE 14. Metacyproidea makie gen. et sp. nov. Holotype, female (OMNH-Ar- 9956), 7.9 mm. A, right gnathopod 1, lateral view; A 1, left coxa 1, lateral view; A 2, posterodistal part of left gnathopod 1, lateral view; B, left gnathopod 2, lateral view; B 1, posterodistal part of left gnathopod 2, lateral view; C – G, left pereopods 3 – 7, lateral views; G 1, left coxa 7, lateral view. Scale: A – G, A 1, G 1, 1 mm; A 2, B 1, 0.5 mm.

FIGURE 15. Metacyproidea makie gen. et sp. nov. Holotype, female (OMNH-Ar- 9956), 7.9 mm. A, left pleonal epimera 1 – 3, lateral view; B, left pleopod 1, posterior view; C, left pleopod 2, lateral view; D, left pleopod 3, posterior view; E, left uropod 1, ventrolateral view; F, right uropod 2, dorsomedial view; G, urosomites 2 – 3, telson and left uropod 3, dorsal view. Scale: B – D, 1 mm; A, E – G, 0.69 mm.

FIGURE 16. Metacyproidea makie gen. et sp. nov. Holotype, female (OMNH-Ar- 9956), 7.9 mm. Type locality, 8 July 2012, photography by K. Tanaka.