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

publication ID

http://dx.doi.org/10.11646/zootaxa.3949.1.4

publication LSID

lsid:zoobank.org:pub:22266A34-5663-4180-91F3-814AA12D8ABE

persistent identifier

http://treatment.plazi.org/id/038D5362-FF97-FFDC-FF7D-FE5AFE81FAC7

treatment provided by

Plazi

scientific name

Victoriopisa wadai
status

sp. nov.

Victoriopisa wadai  sp. nov.

( Figs 1 View Figure 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 View Figure A), sandy-muddy tidal flat, reverse surface of large stone ( Fig. 10 View Figure ), 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 View Figure 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 View Figure ) 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 View Figure A, A 1) 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 View Figure B, B 1 – 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 View Figure C) entire, ventral margin setose. Mandible ( Fig. 12 View Figure D, D 1, E, E 1), 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 View Figure F) with small inner lobes bearing distal setae; medial margins of outer lobes setose, each with small projection. Maxilla 1 ( Fig. 12 View Figure G, G 1), 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 View Figure 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 View Figure I, I 1 – 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 View Figure A, A 1) 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 View Figure B, B 1) 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 View Figure 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 View Figure E, E 1), 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 View Figure F, F 1) 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 View Figure G, G 1) 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 View Figure A), posteroventral corner of epimeron 3 weakly projected; ventral margins of epimera 2 – 3 each with a few setae. Pleopods 1–3 ( Fig. 14 View Figure 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 View Figure 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 View Figure 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 View Figure 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 View Figure 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 View Figure I), accessory flagellum 2 -articulated. Gnathopod 1 ( Fig. 14 View Figure J, J 1) almost similar to that of male, but carpus relatively longer, posterodistal corner with 7 medial robust setae. Gnathopod 2 ( Fig. 14 View Figure K, K 1) 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 View Figure 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 View Figure ).