Peramphithoe eoa Bruggen 1907

Peramphithoe eoa (Brüggen, 1907) (Korean name: Gin-son-ga-lac-cham-yeop-sae-u, new) (figs 7–9) Amphithoe eoa Brüggen, 1907: 481, figs 4–5 (cited from Gurjanova, 1938). — Gurjanova, 1938: 345, figs 46–46a. — 1951: 881, figs 615a–b. — Barnard, 1954: 27, pls 25–26. — Tzvetkova, 1967: 186. Peramphithoe eoa. — Conlan & Bousfield, 1982: 60. Material examined. 1 3, Geojin, Gosung-gun, 24 February 2005 (Y.H. Kim), by fishing net; 4 specimens, Gajin, Gosung-gun, 14 March 2006 (Y.H. Kim), by fishing net; 1 Ƥ, Gajin, Gosung-gun, 24 February 2007 (Y.H. Kim), by fishing net. Type locality. Vladivostok, Russian Far Eastern seas. Diagnosis. Head as long as wide. Eye small, round. Epimeral plates 2–3 subquadrate posteroventrally. Antenna 1 elongate, peduncular article 1 subequal to article 2, flagellum elongate, more than twice the length of peduncle. Antenna 2 about half length of antenna 1, peduncular article 4 subequal in length to article 5, flagellum slightly longer than article 5. Lower lip outer lobe tripartite, medial lobe shorter than lateral lobe. Maxilla 1 inner plate with 3 pinnate setae subapically. In male, gnathopod 1 carpus subequal to propodus. Gnathopod 2 propodus massive, narrowing distally, posterior margin straight; dactylus elongate, longer than propodus. In female, gnathopod 1 propodus slightly longer than carpus. Gnathopod 2 propodus elongate-ovate, palm oblique. Uropod 3 peduncle more than twice the length of rami. Description. Adult male: Body length 19.3 mm, comparatively large-sized species. Head (figs 7, 8A) 1.5 x as long as pereonite 1. Lateral cephalic lobe slightly angular. Eye small, round, located close to lateral cephalic lobe. Antenna 1 weakly setose, very long, slightly shorter than the total body length; peduncular article 1 stouter than and nearly as long as article 2; peduncular article 3 short, 0.26 x as long as article 2, bearing 1 or 2 spines ventrodistally; flagellum very long, 2.85 x as long as peduncle. Antenna 2 0.55 x as long as antenna 1; peduncular articles 1–3 short, article 4 slightly longer than article 5; flagellum 25-articulate, 1.20 x as long as peduncular article 5. Epimera (Fig. 8 B) without seta or spine on ventral margins, curved ventrally. Lower lip (Fig. 8 C) inner lobe pubescent apically; outer lobe tripartite, medial lobe shorter than lateral lobe, both lobes densely pubescent apically. Mandible (Fig. 8 D) incisor and lacinia mobilis dentate, with 9 blunt teeth, respectively; molar truncate, more or less protruding; accessory setal row of 13 setae between lacinia mobilis and molar; palp well developed, triarticulate, proximal article short, distal article 1.38 x as long as article 2, with apical pinnate setae. Maxilla 1 (Fig. 8 E) inner plate relatively small, with 3 pinnate setae subapically; outer plate with 10 sclerotized simple or irregularly serrate spine-teeth; palp biarticulate, distal article with 7 conical spines and 3 pinnate setae. Maxilla 2 inner plate slightly smaller than outer one, both plates distomarginally setose. Gnathopod 1 (Fig. 8 F) coxa subquadrate, bearing simple setae posterodistally; basis 1.26 x as long as merus and carpus combined, with long setae posteromarginally; propodus subequal to carpus, palm transverse, with 1 medial spine; dactylus falcate, with 1 penicillate seta anteroproximally. Gnathopod 2 (Fig. 8 G) coxa D-shaped, roundly curved anteromarginally, with unequal setae on posterodistal margin; basis subrectangular, narrowing proximally, with long simple setae posteromarginally, 1.49 x as long as merus and carpus combined; propodus very large, massive, 1.31 x as long as basis, tapering distally, posterior margin straight, palm obscure; dactylus very long, lacking penicillate seta anteroproximally, 1.17 x as long as propodus, apical portion extending beyond propodus and curved upwards. Pereopod 3 (Fig. 9 A) coxa subquadrate, with unequal setae on ventrodistal margin; basis 1.63 x as long as merus and carpus combined, both margins slightly bulging, posterior margin with long setae; merus 1.18 x as long as carpus, anterodistal part more or less extending toward carpus; subequal in width to length ratio of carpus and propodus; dactylus falcate, with 1 penicillate seta anteroproximally. Pereopod 5 (Fig. 9 B) basis subcircular, relatively plump, 0.89 x as wide as long, 1.24 x as long as merus and carpus combined, with 4 spines on anteromedial margin, simple setae distal half of anterior margin; merus wider and 1.08 x longer than carpus; propodus bearing a row of spines, narrower and 1.45 x longer than carpus. Pereopod 6 (Fig. 9 C) coxa bilobate, anterior lobe roundly protruding downward; basis ovate, with a row of spines on anterior margin; propodus 1.38 x as long as carpus, with a row of spine-setae; dactylus falcate, with 1 penicillate seta anteroproximally; length ratio of articles 2–7 = 1.00: 0.26: 0.67: 0.55: 0.76: 0.26. Uropod 1 (Fig. 9 D) peduncle 1.87 x as long as inner ramus, with enlarged distoventral spur, 5 dorsolateral, 5 dorsomedial spines, and a row of basofacial setae laterally; outer ramus 0.84 x as long as inner one, rami bearing two rows of spines on both margins. Uropod 2 (Fig. 9 E) similar in structure but smaller than uropod 1, distoventral spur relatively short, peduncle 1.27 x as long as rami, with 3 dorsolateral and 2 dorsomedial spines; both rami subequal in length. Uropod 3 (Fig. 9 F) peduncle cylindrical, 2.31 x as long as outer ramus, bearing 3 groups of lateral setae, 2 groups of small spines distally; outer ramus bearing 2 hooked terminal spines, inner ramus with 2 medial spines and small spines and setae apically; both rami subequal in length. Telson (Fig. 9 G) subtriangular, more or less distally truncated, 1.44 x as wide as long, with 5 or 6 lateral setae, 1 or 2 simple and 1 plumose penicillate seta on each submarginal margin. Female. Body length 18.5 mm, similar to male in shape, but carpus of gnathopod 1 (Fig. 9 H) shorter and stouter than that of male, carpus to dactylus of gnathopod 2 (Fig. 9 I) showing sexual dimorphism; gnathopod 1, propodus slightly longer than carpus, gnathopod 2, palm of propodus oblique. Pereopod 7 (Fig. 9 J) slender, coxa small, subrectangular, length ratio of articles 2–7 = 1.00: 0.29: 0.70: 0.56: 0.78: 0.46. Remarks. Peramphithoe eoa (Brüggen, 1907) has morphologically closest affinity to P. baegryeongensis Kim & Kim, 1988. However several morphological differences are found between P. e o a and P. baegryeongensis: 1) the length of antenna 1 of P. e o a relatively longer than P. baegryeongensis; 2) the inner plate of maxilla 1 of P. e o a bearing 3 setae, while 1 seta in P. baegryeongensis; 3) in male, the posterior margin of propodus of gnathopod 2 of P. eoa rather straight, while concave in P. baegryeongensis; 4) in male, dactylus of gnathopod 2 of P. e o a very long, longer than propodus, reach the middle portion of merus, while shorter than propodus in P. baegryeongensis. This species is distributed in the temperate north Pacific. Molecular data. CO1 gene sequences (GenBank accession numbers JN575623 – JN575624) were obtained from two specimens. Sequence alignment was straightforward without any insertion or deletion. Intra-specific variation of the CO1 gene sequence of the species ranged 0.1%, while inter-specific variation ranged from a low of 10.7% (P. e o a and P. namhaensis) to a high of 13.5% (P. e o a and P. t e a) (Figure 12, Table 2). Distribution. North Pacific: Korea (east coast), Japan, Russia, Canada, US.

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