LUCIOBLIVIO KOZAENSIS TOMIKAWA SP. NOV.

Type material: Holotype: female, 6.3 mm (appendages on slides and carcass in ethanol), NSMT-Cr 16662, shallow riverbed of the Koza River (33°32′10″N, 135°47′47″E), Kozagawa Town, Wakayama Prefecture, 11.iii.2004, collected by N. Matsumoto. Paratypes: two females, 4.2 mm (appendages on slide and carcass in ethanol), 3.4 mm (ethanol), NSMT-Cr 16663–16664, from 20 cm depth on the bank of the Seto River (34°52′50″N, 138°13′08″E), Terajima, Fujieda City, Shizuoka Prefecture, 3.xi.2004 , collected by T. Torii; two females, 6.5 mm (appendages on slides and carcass in ethanol), 4.9 mm (ethanol), NSMT-Cr 16665– 16666, shallow riverbed of the Kirime River (33°47′N, 135°14′E), Inami Town, Wakayama Prefecture, February 2001, collected by K. Nishi.

Specimen for SEM observation: Female, 5.6 mm, data as for holotype.

Etymology: The species name is from the Latinized Japanese kozaensis (of Koza), referring to the type locality of the new species.

Description: Holotype, female, NSMT-Cr 16662. Head (Fig. 13): shorter than pereonites 1 and 2 combined; inferior antennal sinus shallow; eyes absent; rostrum short; lateral cephalic lobe weakly pointed. Antenna 1 (Fig. 14A): length about 0.6 × body length; peduncular articles 1, 2 and 3 with length rations 1.0: 0.9: 0.3; posterior margin of article 1 with 3 robust setae, posterodistal part with single robust seta; articles 2–3 with lateral and medial setae; accessory flagellum 2- articulate (Fig. 14B); primary flagellum 20-articulate, each article with 1 aesthetasc, calceoli lacking (Fig. 14C). Antenna 2 (Fig. 14D): about half the length of antenna 1; peduncular articles 4–5 with lateral and medial setae; length of article 4 1.3 × length of article 5; article 5 with 5 calceoli (Fig. 14E); flagellum 11- articulate, articles with calceoli.

Pereonites 1–7 (Fig. 13): smooth, with fine setae. Pleonites 1–3 (Fig. 15E–G): dorsal margin of each with 4 setae. Coxae: coxae 1–4 with marginal and facial setae; posterior margin of coxa 4 widely excavate (Fig. 17C); anterior lobe of coxae 5–6 dominant (Fig. 17E, F); coxa 7 shallow, 0.5 × as deep as wide (Fig. 17H). Urosomites 1–3 (Fig. 15H–J): dorsal margin with pair of robust setae.

Upper lip (Fig. 14F): ventral margin truncate, lacking marginal setae. Lower lip (Fig. 14G): outer lobes broad, shoulder acute, inner lobes fused, indistinct. Mandible (Fig. 14H): left and right incisors 5- and 4-dentate, respectively (Fig. 14I, K); left lacinia mobilis 4-dentate (Fig. 14I), right lacinia finely dentate (Fig. 14K); molar weak, not triturative, without seta; palp articles 1, 2 and 3 with length ratios 1.0: 2.5: 2.5; article 1 unarmed; article 2 with 12 marginal setae; article 3 with 2 A-setae, pair of B-setae, many D- setae, and Esetae, outer face without fine setae, apical margin with fine setae (Fig. 14J). Maxilla 1 (Fig. 14L): inner plate ovate, with 2 apical plumose setae; outer plate with seven robust serrate setae (Fig. 14N); palp article 2 with 3 robust setae and 5 slender setae apically (Fig. 14M). Maxilla 2 (Fig. 14O): inner plate with 2 plumose facial setae in oblique row. Maxilliped (Fig. 15A): inner plate short, reaching base of palp article 1, quadrate, apically with 1 robust seta and 2 weakly plumose setae (Fig. 15B); outer plate narrowing distally, not reaching middle of palp article 2, with row of robust setae extending from apex along medial margin (Fig. 15C); palp article 2 long, length 1.9 × length of article 1 and 1.8 × length of article 3; articles 2 and 3 medially setose, article 3 with apical lobe.

J

E

F

Gnathopods: dissimilar in size and form. Gnathopod 1 (Fig. 16A): anterior and posterior margins of basis with long setae; ischium and merus short, ventral margin of merus setose; carpus short, length 0.3 × length of propodus, not lobate, with medial setae, ventral margin lined with setae; propodus stout, palm lined with small triangular protuberances, 16 robust setae, inner distal corner with 3 robust setae (Fig. 16B); dactylus curved, posterior margin smooth (Fig. 16B). Gnathopod 2 (Fig. 16C): anterior and posterior margins of basis with long setae; carpus long, length 0.6 × length of propodus, with medial setae, not lobate, ventral margin lined with setae; propodus more slender than that of gnathopod 1, palm lined with small triangular protuberances, 12 robust setae, inner distal corner with 2 robust setae (Fig. 16D); dactylus curved, posterior margin smooth (Fig. 16D).

Pereopod 3 (Fig. 17A): slender, anteroproximal and posterior margins of basis with long setae; ischium short, almost as long as width; length ratios of merus, carpus and propodus = 1.0: 1.0: 0.8, with short setae marginally; length of dactylus 0.4 × length of propodus, anteroproximal and posterior margin each with single seta (Fig. 17B). Pereopod 4 (Fig. 17C): like pereopod 3, except: length ratios of merus, carpus and propodus = 1.0: 1.1: 1.0; length of dactylus 0.3 × length of propodus (Fig. 17D). Pereopod 5 (Fig. 17E): anterior margin of basis with robust setae, posterior margin with fine setae, posteroventral lobe rounded; ischium short, about as long as wide; merus–dactylus missing. Pereopod 6 (Fig. 17F): like pereopod 5, except: length of ischium 1.2 × its width; length ratios of merus, carpus and propodus = 1.0: 1.4: 1.4; dactylus slender, length 0.2 × length of propodus, with short seta anteriorly (Fig. 17G). Pereopod 7 (Fig. 17H): like pereopod 5, except: ischium short, length 0.9 × width; length ratios of merus, carpus and propodus = 1.0: 1.4: 1.4; dactylus stout, length 0.2 × length of propodus, with anterior seta (Fig. 17I).

F

Brood plates: narrow, lacking brood setae, on pereopods 2–5. Pleopods (Fig. 17J, M, N): peduncle and rami long; retinacula paired, without associate setae (Fig. 17K); inner basal margin of inner ramus of pleopods 1–3 with 3, 2, and 2 bifid setae, respectively (Fig. 17L); outer ramus 12-, inner ramus 9-articulate. Epimeral plates 1–3 (Fig. 15K–M): not pointed posterodistally, lacking ventromarginal setae, posterior margins with 1, 1, and 3 setae, respectively.

Uropod 1 (Fig. 15N): length of peduncle 1.2 × length of inner ramus, with robust setae on dorsolateral and dorsomedial margins, and with 4 basofacial robust setae; length of outer ramus 0.9 × length of inner ramus, outer and inner margins each with 2 robust setae; outer and inner margins of inner ramus with 2 and 4 robust setae, respectively. Uropod 2 (Fig. 15O): length of peduncle 0.8 × length of inner ramus, with robust setae on dorsolateral and dorsomedial margins; length of outer ramus 0.6 × length of inner ramus, with 3 robust setae dorsally; outer and inner margins of inner ramus with 2 and 4 robust setae, respectively. Uropod 3 (Fig. 15P–R): length of peduncle 0.4 × length of inner ramus, with single robust seta; outer ramus uniarticulate, outer margin with pair of robust setae and 2 clusters of robust setae, and single robust seta; inner margin with single simple seta, 2 robust setae, and 2 pairs of robust setae; inner ramus long, length 0.9 × length of outer ramus, outer margin with single simple seta and 3 robust setae. Telson (Fig. 15S): length 1.6 × basal maximum width, dorsolateral margins with 2 robust setae and 2 fine setae, each lobe with robust seta apically; cleft 48%.

SEM observation: One female was observed via SEM. Calceolus (Fig. 18A, B), stalk, and bulla well developed; concavity of proximal element shallow; distal

Eogammarus kygi

Locustogammarus locustoides

Barrowgammarus macginitiei

Jesogammarus jesoensis

Spasskogammarus spasskii

Anisogammarus pugettensis

Carineogammarus makarovi

Lucioblivio kozaensis

Gammarus nipponensis

Mesogammarus melitoides

Octopupilla felix

Eoniphargus kojimai

Crangonyx floridanus

Melita sp.

0.02

Figure 19. A, strict consensus tree obtained by maximum parsimony analysis; B, neighbour-joining tree. Numbers near branches indicate bootstrap values> 50%. Trees rooted by the outgroup taxon Melita sp.

element with ten well-defined transverse bands. Lacinia mobilis of right mandible not bifid (Fig. 18C, D); molar weak, not tritulative (Fig. 18C, E).

Remarks: This species occurs sympatrically with Eoniphargus kojimai at Seto River, Shizuoka Prefecture, and with Octopupilla felix at Koza River, Wakayama Prefecture.