Victoriopisa wadai, Ariyama, Hiroyuki, 2015

Ariyama, Hiroyuki, 2015, Three new species of the Eriopisa group (Crustacea: Amphipoda: Eriopisidae) from Japan, with the description of a new genus, Zootaxa 3949 (1), pp. 91-110 : 104-109

Victoriopisa wadai sp. nov.

( Figs 1 A–B, 10–14)

Material examined. Holotype: male (OMNH-Ar-9721), 7.2 mm, mouth of Kamo River in Saijo City, Ehime Prefecture, 33°55'57"N, 133°09'09"E ( Fig. 1 A), sandy-muddy tidal flat, reverse surface of large stone ( Fig. 10 ), 29 June 2014, coll. T. Wada. Paratypes: 1 male (OMNH-Ar-9722), 7.6 mm, same data as holotype; 1 ovigerous female (OMNH-Ar-9723), 7.9 mm, same locality as holotype, 27 June 2014, coll. T. Wada; 1 female (OMNH-Ar-9724), 4.6 mm, and 3 juveniles (OMNH-Ar-9725–9727), 3.4, 2.9, 2.8 mm, mouth of Doki River in Marugame City, Kagawa Prefecture, 34°18'10"N, 133°48'07"E ( Fig. 1 B), muddy tidal flat, reverse surface of large stone, 22 September 2014, coll. T. Wada.

Description. Male [based on holotype, 7.2 mm (OMNH-Ar-9721) and paratype, 7.6 mm (OMNH-Ar-9722) for upper lip and lower lip]. Body ( Fig. 11 ) slender, depressed laterally, smooth; urosomites free; pleonite 3 and urosomites 1 – 3 each with dorsal seta. Head longer than pereonite 1, rostrum obsolescent, eyes absent; lateral cephalic lobe rounded, anteroventral sinus indistinct.

Antenna 1 ( Fig. 12 A, A1) very long, with ratio of lengths of peduncular articles 1–3 1:0.9:0.3, article 1 with 2 medial robust setae; accessory flagellum short, uniarticulated, with 5 setae distally; primary flagellum with 28 articles. Antenna 2 ( Fig. 12 B, B1 – 2) short, with ratio of lengths of peduncular articles 3–5 1:1.8:2.0; flagellum short, with 2 fused long articles and 3 short articles.

Upper lip ( Fig. 12 C) entire, ventral margin setose. Mandible ( Fig. 12 D, D1, E, E1), each incisor bearing 6 cusps, lacinia mobilis with 5 cusps in left, 3 cusps in right, accessory blades 4 (overlapped?) in left, 10 in right; molar strong; palp article length ratio 1:4.9: 3.7 in left, 1:3.9: 3.3 in right, article 2 with 3–4 setae ventrally, article 3 with 2 proximal and 9 distal setae. Lower lip ( Fig. 12 F) with small inner lobes bearing distal setae; medial margins of outer lobes setose, each with small projection. Maxilla 1 ( Fig. 12 G, G1), inner plate roundish, with several distal setae; outer plate with 9 robust setae apically; palp 2-articulated, tip of article 2 projected, with 4 robust setae. Maxilla 2 ( Fig. 12 H), inner plate as wide as outer, dorsal surface of inner plate with oblique row of setae, terminal ends of both plates setose. Maxilliped ( Fig. 12 I, I1 – 2), inner plate truncate, distal end bearing 4 short robust setae; outer plate produced distomedially, without long robust setae; palp 4-articulated, article 4 with short nail.

Gnathopod 1 ( Fig. 13 A, A1) small, subchelate; coxa short, trapezoidal; basis widened in distal three fourths, posterior margin with 2 long setae, posterodistal corner setose; lateral and medial surfaces of merus covered with thin setae, distal margin with long setae; posterior margin of carpus heavily setose; propodus short, 65 % as long as carpus, widened distally, posterodistal corner with 5 medial robust setae, palm transverse; dactylus short, curved. Gnathopod 2 ( Fig. 13 B, B1) large, subchelate; coxa short, roundish rectangular, gill very large, curved posteriorly; basis widened in distal three fourths, posterior margin with 4 long setae, posterodistal corner setose; carpus lobed, posterior margin setose; propodus dilated, about 2.3 times as long as carpus, anterodistal corner setose, proximal part of posterior margin with 2 bundle of setae; palm oblique, composed of 3 lobes, 2 excavations and large robust seta, first lobe with 4 medial robust setae, second lobe with medial robust seta, third lobe without setae; dactylus stout, strongly curved.

Pereopods 3–4 ( Fig. 13 C – D) similar, slender; coxae short, rectangular, gills very large; bases linear, posterior margins with several long setae; meri slender, widened distally; dactyli narrow, slightly curved. Pereopod 5 ( Fig. 13 E, E1), posterior lobe of coxa a little shorter than anterior lobe, gill large, oval; basis longish oval, posterodistal corner rounded; merus slightly expanded; carpus with 2, 2 and 5 robust setae on anterior margin, anterodistal and posterodistal corners, respectively; dactylus short. Pereopod 6 ( Fig. 13 F, F1) about 1.3 times as long as pereopod 5; posterior lobe of coxa a little shorter than anterior lobe, gill small; basis longish oval, posterodistal corner rounded like pereopod 5; merus slightly expanded; anterior margin and anterodistal and posterodistal corners of carpus each with 4 robust setae; anterior margin and anterodistal corner of propodus each with 2 robust setae; dactylus narrow. Pereopod 7 ( Fig. 13 G, G1) about 1.2 times as long as pereopod 6; coxa short rectangular, not lobed; basis oval, posterodistal corner greatly swelled; merus moderately expanded, with 3 posterior robust setae; anterior margin and anterodistal and posterodistal corners of carpus with 4, 4 and 2 robust setae, respectively; anterior margin and anterodistal corner of propodus bearing 1 and 2 robust setae, respectively; dactylus narrow.

Pleonal epimera ( Fig. 14 A), posteroventral corner of epimeron 3 weakly projected; ventral margins of epimera 2 – 3 each with a few setae. Pleopods 1–3 ( Fig. 14 B–D) long, similar in length; peduncles short, each with several anterior and lateral setae and 2 coupling hooks; inner rami subequal to outer, inner and outer rami with 15 and 20 articles in pleopod 1, 14 and 18 articles each in pleopod 2–3, respectively. Uropod 1 ( Fig. 14 E) biramous, long; peduncle bearing 2 ventrofacial and 5 dorsolateral robust setae, distomedial and distolateral corners with 1 and 3 robust setae, respectively; inner ramus 62 % length of peduncle, with 1 medial and 6 distal robust setae; outer ramus 57 % length of peduncle, with 2 medial, 1 lateral and 6 distal robust setae. Uropod 2 ( Fig. 14 F) biramous, short, about half length of uropod 1; peduncle short, bearing 2 and 1 robust setae on dorsolateral margin and distolateral corner, respectively; inner ramus 93 % length of peduncle, with 1 medial and 5 distal robust setae; outer ramus 67 % length of peduncle, with 1 lateral and 5 distal robust setae. Uropod 3 ( Fig. 14 G) extremely long, about 2.6 times as long as uropod 1, biramous; peduncle short, with 1 and 2 robust setae on ventral surface and ventrodistal margin, respectively; inner ramus very short, scale-like, 29 % length of peduncle, with a few setae distally; outer ramus very long, about 3.4 times as long as peduncle; article 1 with several setae on medial margin and dorsal and ventral surfaces, distomedial corner with 2 robust setae, article 2 about 1.2 times as long as article 1, medial margin with 6 robust setae, medial and dorsal surfaces bearing several setae, distal margin with many long setae. Telson ( Fig. 14 G, H) longer than broad, deeply incised; each lateral margin with 2 robust setae; each distal ends bearing robust seta, dorsal surface with pair of 1 and 2 plumose setae.

Female [paratype, 7.9 mm (OMNH-Ar-9723)]. Generally similar to male except for antenna 1, gnathopods and oostegites. Antenna 1 ( Fig. 14 I), accessory flagellum 2-articulated. Gnathopod 1 ( Fig. 14 J, J1) almost similar to that of male, but carpus relatively longer, posterodistal corner with 7 medial robust setae. Gnathopod 2 ( Fig. 14 K, K1) almost similar to that of male, but coxa parallelogramatic, palm composed of 2 lobes, 1 excavation and large robust seta, first lobe with 6 medial robust setae, second lobe without setae. Oostegites present on coxae 2–5.

Juvenile [Paratype, 3.4 mm (OMNH-Ar-9725)]. Gnathopod 2 ( Fig. 14 L), palm smooth, with 3 small and 1 large medial robust setae.

Coloration in life. Whole body translucent white.

Etymology. Dedicated to Taichi Wada for donating many amphipod specimens collected from various tidal flats.

Remarks. Lim et al. (2010) enumerated eight species in the genus Victoriopisa . But, in addition to those, two species and one subspecies were described: V. chilkensis griffithsi G.S. Karaman, 1984 ; V. guanarocana Ortiz & Lalana, 1989 ; V. ovate ( Dang & Le, 2005) as Eriopisa ovata . Victoriopisa wadai sp. nov. has the following characters: (1) eyes absent, (2) peduncle of antenna 1 not heavily setose, (3) accessory flagellum with 1–2 articles, (4) flagellum of antenna 2 composed of 2 long and 3 short articles, (5) gnathopod 2 in both sexes with excavated palm, (6) merus of pereopod 7 moderately expanded, and (7) ventral margin of pleonite 2 slightly setose. All species and subspecies of the genus do not have this combination of the characters [see Lim et al. (2010)]. In particular, the gnathopod 2 with excavated palm is a unique character in the genus. Victoriopisa ryukyuensis from Japan differs from this new species in the presence of eyes, the heavily setose peduncle of antenna 1, the greatly expanded merus of pereopod 7, and the setose ventral margin of pleonite 2.

Habitat. Brackish with fluctuating salinity. Reverse surface of large stone on sandy-muddy or muddy tidal flat ( Fig. 10 ).

Figures

FIGURE 1. Map showing the collecting sites. A – B, Victoriopisa wadai sp. nov.; C, Paraflagitopisa excavata gen. et sp. nov. and Psammogammarus lobatus sp. nov.

FIGURE 10. Victoriopisa wadai sp. nov. Holotype, male (OMNH-Ar- 9721), 7.2 mm, and paratype, male (OMNH-Ar- 9722), 7.6 mm. Photography by T. Wada.

FIGURE 11. Victoriopisa wadai sp. nov. Holotype, male (OMNH-Ar- 9721), 7.2 mm. Habitus, lateral view. Scale: 1 mm.

FIGURE 12. Victoriopisa wadai sp. nov. All except for B 2, C and F, holotype, male (OMNH-Ar- 9721), 7.2 mm; B 2, C, F, paratype, male (OMNH-Ar- 9722), 7.6 mm. A, right antenna 1, lateral view; A 1, accessory flagellum of right antenna 1, lateral view; B, right antenna 2, lateral view; B 1, flagellum of right antenna 2, lateral view, setae omitted; B 2, flagellum of left antenna 2, lateral view, setae omitted; C, upper lip, anterior view; D, left mandible, medial view; D 1, incisor, lacinia mobilis, accessory blades and molar of left mandible, medial view; E, right mandible, medial view; E 1, incisor, lacinia mobilis, accessory blades and molar of right mandible, medial view; F, lower lip, ventral view; G, left maxilla 1, dorsal view; G 1, distal part of left maxilla 1, dorsal view, normal setae omitted; H, left maxilla 2, ventral view; I, left maxilliped, ventral view; I 1, distal part of inner plate of left maxilliped, ventral view, normal setae omitted; I 2, distal part of outer plate of left maxilliped, ventral view, normal setae omitted. Scale: A, 2 mm; B, 1 mm; B 1 – 2, C – I, 0.5 mm; A 1, D 1, E 1, G 1, I 1 – 2, 0.25 mm.

FIGURE 13. Victoriopisa wadai sp. nov. Holotype, male (OMNH-Ar- 9721), 7.2 mm. A – B, left gnathopods 1 – 2, lateral views; A 1, B 1, palms of left gnathopods 1 – 2, lateral views, normal setae omitted; C – G, left pereopods 3 – 7, lateral views; E 1, F 1, G 1, posterior parts of carpi of left pereopods 5 – 7, lateral views. Scales: A – G, 1 mm; B 1, E 1, F 1, G 1, 0.5 mm; A 1, 0.25 mm.

FIGURE 14. Victoriopisa wadai sp. nov. A – H, holotype, male (OMNH-Ar- 9721), 7.2 mm; I – K, paratype, female (OMNH-Ar- 9723), 7.9 mm; L, paratype, juvenile (OMNH-Ar- 9725), 3.4 mm. A, left pleonal epimera 1 – 3, lateral view; B, left pleopod 1, posterior view; C, left pleopod 2, anterior view; D, left pleopod 3, posterior view; E, left uropod 1, dorsolateral view; F, left uropod 2, dorsomedial view; G, left uropod 3 and telson, dorsal view; H, telson, dorsal view; I, accessory flagellum of right antenna 1, medial view; J – K, left gnathopods 1 – 2, lateral views; J 1, K 1, palms of left gnathopods 1 – 2, lateral views, normal setae omitted; L, propodus and dactylus of left gnathopod 2, lateral view, normal setae omitted. Scale: G, 1.33 mm; A – D, J – K, 1 mm; E – F, 0.67 mm; H, K 1, L, 0.5 mm; I, J 1, 0.25 mm.