Leipsuropus Stebbing, 1899

Ariyama, Hiroyuki, 2012, Two new species of the genus Leipsuropus (Crustacea: Amphipoda: Podoceridae) from Japanese and Korean waters, Zootaxa 3485, pp. 41-55 : 42

Genus Leipsuropus Stebbing, 1899

Leipsuropus Stebbing, 1899: 241 .— Stebbing, 1906: 698.— Barnard, 1969: 430.— Laubitz, 1983: 79.— Barnard & Karaman, 1991: 661.— Myers & Lowry, 2003: 470.— Lowry & Stoddart, 2003: 245.— Ren, 2012: 391.— Hughes, 2012: 76.

Type species. Cyrtophium parasiticum Haswell, 1879 by monotypy.

Diagnosis. Body depressed dorsoventrally, dorsal surface with projections or rugae, lateral surface with or without projections, pereonites 6, 7 free or partially fused; urosomites free, urosomite 1 elongate. Head longer than pereonite 1, rostrum short, ocular lobes obsolescent, antennal sinus deep. Antennae long, strongly setose ventrally; antenna 1 peduncular article 1 much shorter than article 3, accessory flagellum vestigial, primary flagellum with 2– 5 articles; antenna 2 peduncular articles 2, 3 elongate, flagellum with 1 long and 1–2 vestigial articles. Upper lip broad, with a hollow on ventral margin; epistome produced anteriorly. Mandible, palp strong, article 2 longest; incisor, lacinia mobilis and accessory blades developed. Inner lip with well-developed inner lobes and short mandibular lobes, apical parts of inner and outer lobes covered with thin setae. Maxilla 1, inner plate vestigial, without setae; outer plate with 8(–9) robust setae apically; palp 2-articulated, article 2 bearing several robust setae on tip. Maxilla 2, inner plate narrower than outer, terminal ends of both plates setose. Maxilliped, inner plate small; medial margin of outer plate bearing row of robust setae; palp 4-articulated, article 2 long, article 4 short. Coxae small, short, weakly overlapping; coxa 1 produced forward, coxae 2–4 larger than other, coxae 5, 6 lobed, coxa 7 smallest; gills large, present on coxae 2–6. Gnathopod 1 of both sexes similar, small, subchelate; carpus subequal to propodus. Male gnathopod 2 enlarged, subchelate; basis stout, carpus obsolescent, unlobed, propodus dilated, posterior margin setose, with 1–3 large processes, dactylus robust. Female gnathopod 2 smaller than that of male, subchelate; posterior margin of propodus less setose, palm defined by small process. Pereopods 3–7 similar, slender, propodi long, pereopods 3–5 shorter than pereopods 6, 7. Oostegites of female present on coxae 2–4. Pleonal epimera 1–3 rounded. Uropod 1 long, biramous, outer ramus shorter than inner; peduncle and both rami bearing robust setae. Uropod 2 absent. Uropod 3 situated beneath telson; small, lacking rami, lanceolate; distal margin setose. Telson entire, short.

Remarks. The genus Leipsuropus is unique in the family Podoceridae in the absence of uropod 2, whereas the genus Laetmatophilus Bruzelius, 1859 has only two urosomites and uropod 2 without rami. The other genera of the family have biramous uropod 2. The diagnosis deviates from that of Barnard & Karaman (1991) in the pereonites 6, 7. They stated “partially fused”; however, the Leipsuropus species except for L. parasiticus have free pereonites 6, 7.