Terepeltopes dolichorhunia Hirayama, 1983

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 : 325-330

Terepeltopes dolichorhunia Hirayama, 1983

[Japanese name: Tsubasa-biyadaruyokoebi] ( Figs 21–25 )

Terepeltopes dolichorhunia Hirayama, 1983: 118 , figs 26–28 (type locality: Shijiki Bay, Hirado City, Nagasaki Prefecture, Japan).— Barnard & Karaman, 1991: 259.— Ishimaru, 1994: 53.— Jung et al., 2015: 127, figs 1–3.

Material examined. Two ovigerous females and 1 female (OMNH-Ar-9966–9968), 3.1, 3.1, 3.0 mm, Koganezakipark beach, Nishi-izu Town, Shizuoka Prefecture, 34°50'37"N, 138°45'49"E, 10–12 m in depth, sandy bottom, using SCUBA, 17 July 2012, coll. M. Fujii; 1 male? (OMNH-Ar-9969), 2.1 mm, mouth of Moroiso Bay, Misaki City, Kanagawa Prefecture, 35°09'25"N, 139°36'37"E, 4.5–5.0 m in depth, sandy bottom, using dredge, 14 July 2014, coll. H. Kohtsuka; 1 ovigerous female (OMNH-Ar-9970), 3.5 mm, Kodomari Bay, Yashiro Island, Suooshima Town, Yamaguchi Prefecture, 1 m in depth, sandy bottom, using sled net, 11 December 1997, coll. Y. Hanamura.

Description. Female [based on 3.1 mm (OMNH-Ar-9966), and 3.1 mm (OMNH-Ar-9967) for maxilla 1 and coxa 1]. Body ( Fig. 21 ) roundish mountain-shaped; head longer than pereonite 1, anterior margin with ventrallyoriented spine, eyes medium-sized; pereonites and pleonites smooth, with pereonites 3–5 (especially pereonite 4) enlarged; coxa 5 barely reaching posteroventral corner of pereonite 5; pleonites without lateral ridge, pleonal epimera 1–3 rounded each on posteroventral corner, all ventral margins bare; urosomite 1 long, dorsal margin with large keel projected dorsally, tip of keel pointed, urosomites 2–3 very short.

Antenna 1 ( Fig. 22 A) short, with ratio of lengths of peduncular articles 1–3 1:0.6:0.4; accessory flagellum absent; primary flagellum with 4 articles (articles 2–3 very short), with many aesthetascs. Antenna 2 ( Fig. 22 B) short; peduncular article 3 short and articles 4–5 relatively long; flagellum with 4 articles, tip bearing a few long setae.

Upper lip ( Fig. 22 C) incised, asymmetrical. Mandible ( Fig. 22 D, D1, E, E1), incisor bearing 10 cusps in left and 8 cusps in right, left lacinia mobilis fan-shaped, distal margin 8-dentated, right lacinia mobilis small, cylindrical, number of accessory blades 9 in left and 8 in right; molar developed; palp article length ratio 1:1.6: 2.2 in left, all articles without setae. Lower lip ( Fig. 22 F), inner lobes indistinct; outer lobes projected anteriorly, covered with fine setae, each medial margin bearing small projection, mandibular processes vestigial. Maxilla 1 ( Fig. 22 G, G1), inner plate longish triangular, without distal setae; distal end of outer plate with 8 robust and 8 normal setae; distal end of palp bearing 3 blunt robust setae. Maxilla 2 ( Fig. 22 H) slender; inner plate shorter than outer, terminal ends of inner and outer plates with 1 inverted-triangular robust setae and 1 blunt robust setae, respectively. Maxilliped ( Fig. 22 I, I1), inner plate truncate, dorsodistal part bearing 4 small robust setae; outer plate small, distal end with 1 robust seta, mediodistal margin with 2 small robust setae; palp consisting of 4 articles, mediodistal corner with 3 belt-shaped setae, article 3 narrow, with large apicodistal process, medial margin bearing 2 belt-shaped setae, article 4 slender.

Gnathopod 1 ( Fig. 23 A, A1), coxa small, distorted pentagonal, ventral margin with 2 setae; basis straight, anterior margin setose; merus short; carpus long, posterior margin with 2 setae, posterodistal projection bearing several distal setae; propodus longer than carpus, with 1 anterior and 2 posterodistal setae; dactylus long, posterior margin with 1 denticle. Gnathopod 2 ( Fig. 23 B) same length as gnathopod 1; coxa small, roundish rectangular, anterodistal corner with 1 seta; basis stout, slightly widened distally, anterior margin setose; merus short, distal end with several setae; carpus long, posterior margin with 1 seta, posterodistal projection bearing several distal setae; propodus shorter than carpus, slightly widened distally, posterodistal corner with small spine and 2 setae; dactylus short, posterior margin with 1 denticle.

Pereopod 3 ( Fig. 23 C), coxa wide, semicircular, anterior margin rounded, posterior margin slightly concave, posteroproximal corner with small projection; basis long, slender, anterior margin heavily setose. Pereopod 4 ( Fig. 23 D), coxa extremely wide, middle–ventral part swollen posteriorly, anterior margin slightly convex; basis long, slender, anterior margin heavily setose. Pereopod 5 ( Fig. 23 E), coxa relatively large, parallelogramatic, posterodistal corner roundly projected; basis narrow, anterior and posterior margins bearing sparse setae; posterodistal corner of merus projected. Pereopod 6 ( Fig. 23 F), coxa semiquadrate, produced posteroventrally; basis almost straight, anterior and posterior margins with several setae; posterodistal corner of merus projected. Pereopod 7 ( Fig. 23 G) shorter than pereopod 5; coxa roundish pentagonal; basis wide, roundly swollen; merus projected posterodistally.

Pleopods ( Fig. 24 A–C), pleopod 3 shortest; peduncles of pleopods 1–2 bare, pleopod 3 with 2 short setae; inner rami with 7 articles and outer rami with 8 articles in all. Uropods ( Fig. 24 D–F) slender, peduncle and both rami without robust setae, but bearing minute denticles; peduncle of uropod 1 long, both rami 93% length of peduncle; uropod 2 84% as long as uropod 1, inner ramus longer than outer, about 1.1 times as long as peduncle, outer ramus about 0.9 times length of peduncle; uropod 3 short, about 0.6 times as long as uropod 1, peduncle short, inner ramus longer than outer, inner and outer rami about 1.4 and 0.8 times as long as peduncle, respectively. Telson ( Fig. 24 F) roundish triangular, breadth 55% of length, dorsal surface and margins bare.

Small individuals (male?) [based on 2.1 mm (OMNH-Ar-9969)]. Gnathopods almost similar to female except for oostegite on coxa 2.

Coloration in fixed specimen ( Fig. 25 ). Head and antennae brown, eyes red; pereonites and pleonites light brown with brown mottles; coxa 3 wholly brown, coxa 4 brown with white anteroventral and posteroventral marks, coxa 5 brown.

Remarks. Morphological characters of these specimens almost agree with the description and figures of Hirayama (1983). However, the numbers of setae on the maxilla 1 are different (the original description in parentheses): the inner plate without setae (with 1 seta), the outer plate with 8 robust setae and 8 normal setae (with 13 setae and 6 teeth), and the palp with 3 robust setae (with 4 teeth). In the maxilla 1 of Korean specimens, the outer plate has 9 stout and 4 minute spines and the palp has 4 setae ( Jung et al. 2015).

Distribution. Japan: Misaki City in Kanagawa Prefecture, Nishi-izu Town in Shizuoka Prefecture, Suooshima Town in Yamaguchi Prefecture (present study, Fig. 1 ); Shijiki Bay in Nagasaki Prefecture ( Hirayama 1983). Korea: from Gyeongsangnam-do to Incheon-si ( Jung et al. 2015).

Habitat. Sandy bottom, 1–12 m in depth (present study). This species occurs together with Cyproidea liodactyla in Nishi-izu Town.

Figures

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

FIGURE 21. Terepeltopes dolichorhunia Hirayama, 1983. Female (OMNH-Ar- 9966), 3.1 mm. Habitus, lateral view.

FIGURE 22. Terepeltopes dolichorhunia Hirayama, 1983. All except for G and G 1, female (OMNH-Ar- 9966), 3.1 mm; G, G 1, female (OMNH-Ar- 9967), 3.1 mm. A, left antenna 1, lateral view; B, left antenna 2, lateral view; C, upper lip, posterior view; D, left mandible, medial view; D 1, incisor, lacinia mobilis and accessory blades of left mandible, medial view; E, right mandible, dorsal view, palp damaged; E 1, incisor, lacinia mobilis and accessory blades of right mandible, dorsal view; F, lower lip, ventral view; G, left maxilla 1, lateral view; G 1, distal part of left maxilla 1, lateral view, normal setae omitted; H, left maxilla 2, dorsal view; I, left maxilliped, ventral view; I 1, distal part of inner plate of left maxilliped, dorsal view, normal setae omitted. Scale: A – B, 0.2 mm; C – I, 0.15 mm; D 1, E 1, G 1, I 1, 0.075 mm.

FIGURE 23. Terepeltopes dolichorhunia Hirayama, 1983. All but A 1, female (OMNH-Ar- 9966), 3.1 mm; A 1, female (OMNH-Ar- 9967), 3.1 mm. A – B, left gnathopods 1 – 2, lateral views; A 1, left coxa 1, lateral view; C – G, left pereopods 3 – 7, lateral views. Scale: 0.25 mm.

FIGURE 24. Terepeltopes dolichorhunia Hirayama, 1983. Female (OMNH-Ar- 9966), 3.1 mm. A, left pleopod 1, anterior view; B, left pleopod 2, posterior view; C, left pleopod 3, medial view; D, left uropod 1, medial view; E, left uropod 2, dorsal view; F, telson and right uropod 3, dorsal view. Scale: A – C, 0.25 mm; D – F, 0.15 mm.

FIGURE 25. Terepeltopes dolichorhunia Hirayama, 1983. Female (OMNH-Ar- 9968), 3.0 mm. Fixed specimen, 21 July 2012 (4 days after fixation), photography by H. Ariyama.