Elasmopus laminischia, Myers, A. A., 2016

Myers, A. A., 2016, Amphipoda (Crustacea) from Palau, Micronesia: Families Maeridae and Melitidae, Zootaxa 4170 (3), pp. 451-474 : 455-459

Elasmopus laminischia sp. nov.

( Figs 4–7 )

Type material. Holotype male, 3.5 mm (OUMNH.ZC. 2002-24 -144), Uchelbeluu Reef, rubble reef slope, from Galaxea fascicularis (Linnaeus, 1767) ( Scleractinia : Oculinidae ), - 3 m depth; 07°15.644'N 134°32.392'E; leg. S. De Grave & C. Burras, 25 May 2002. Paratypes. 3 females ( OUMNH.ZC. 2002-24 -145), same data as holotype .

Other material. 1 female (OUMNH.ZC. 2002-24 -146), Lighthouse Reef, outer side, from dead Acropora colony overgrown with red filamentous algae, - 25 m depth; 07°16.615'N, 134°27.606'E; leg. S. De Grave & C. Burras, 21 May 2002; 1 male, 1 female (OUMNH.ZC. 2002-24 -147), Lighthouse Reef, outer side, from rubble (mainly Acropora plates and bushy forms, heavily encrusted), - 5 m depth; 07°16.615'N, 134°27.606'E; leg. S. De Grave & C. Burras, 21 May 2002; 3 females (OUMNH.ZC. 2002-24 -148), Beluu Lukes Reef, eastern side, from consolidated rubble, 10 m depth; 07°17.530'N, 134°30.870'E; leg. S. De Grave & C. Burras, 19 May 2002; 1 male (OUMNH.ZC. 2002-24 -149), Beluu Lukes Reef, eastern side, from heavily encrusted loose rubble, - 5 m depth; 07°17.530'N, 134°30.870'E; leg. S. De Grave & C. Burras, 20 May 2002; 1 male, 1 female (OUMNH.ZC. 2002-24 - 150), Beluu Lukes Reef, drop off, - 15m depth; from Melophlus sarasinorum Thiele, 1899 (Porifera: Ancorinidae ); 07°17.530'N, 134°30.870'E; leg. S. De Grave & C. Burras, 2 June 2002.

Type locality. Uchelbeluu Reef , Palau, 07°15.644'N 134°32.392'E.

Etymology. From ‘ lamina’ (latin = blade) referring to the blade-like extension on the inner face of the ischium of the male gnathopod 2.

Description. Based on male holotype, 3.5 mm.

Head. Head with sub-ocular notch; eye round. Antenna 1 a little over half body length; peduncular articles 1 and 2 subequal in length; article 3 about half length of article 2; accessory flagellum with one article; primary flagellum subequal in length with peduncle, with 18 articles. Antenna 2 weak, less than half length of antenna 1; peduncular articles 4 and 5 subequal in length, flagellum subequal in length with peduncular article 5, with 6 articles. Mouthparts of typical Elasmopus form; mandibular palp articles 2 and 3 subequal; article 3 falcate.

Pereon. Gnathopod 1 coxa with anterodistal extension; basis stout, weakly expanded distally; carpus and propodus slender, sub-equal, palm very oblique; dactylus fitting palm. Gnathopod 2 coxa subquadrate; basis greatly expanded distally with rounded anterodistal lobes; ischium with large blade-like blunt and irregular-ended expansion on the anterior inner face; carpus very reduced, cup-shaped; propodus elongate, almost parallel-sided; palm with two acute spines separated by subquadrate excavation; dactylus overlapping palm. Pereopods 3–4 coxa subovate; propodus with serrate spine opposing dactylus; dactylus less than half length of propodus with protrusion on posterior margin. Pereopod 5 basis subquadrate, posterior margin with large weakly concave, weakly serrated, posterodistal corner expanded. Pereopod 6 basis posterior margin with large sub-straight, weakly serrated flange. Pereopod 7 basis posterior margin with large convex, serrated flange.

Pleon. Epimeron 1 with weak spine on posterodistal corner. Epimeron 2 with strong spine on posterodistal corner. Epimeron 3 posterodistal corner with 5 spines. Uropod 1 peduncle sub-equal in length with rami, with numerous robust setae and a long terminal stout robust seta; rami sub-equal in length, Uropod 2 peduncle shorter than rami; inner ramus stouter and longer than outer ramus. Uropod 3 inner ramus shorter and much more slender than outer ramus. Telson as broad as long, distal lobes rounded, each lobe with one long and one short robust seta.

Female (sexually dimorphic characters). Based on female, 3.6 mm. Gnathopod 2 basis relatively slender; carpus long sub-triangular; propodus longer than carpus; palm oblique, weakly convex; dactylus fitting palm.

Habitat. Coral rubble.

Remarks. This species resembles E. hooheno Barnard, 1970 , from Hawaii, but differs in the male gnathopod 2 in which the spine on the centre of the palm is acute (blunt-ended in E. hooheno ) and in the blade-like truncated projection of the inner face of the ischium. It also differs in the strongly scalloped posterior margin of the epimeron 3 (not or weakly scalloped in E. hooheno ).

Distribution. Known only from Palau.

Figures

FIGURE 4. Elasmopus laminischia sp. nov., male paratype, Uchelbeluu Reef, Palau.

FIGURE 5. Elasmopus laminischia sp. nov., male and female paratypes, Uchelbeluu Reef, Palau.

FIGURE 6. Elasmopus laminischia sp. nov., male paratype, Uchelbeluu Reef, Palau.

FIGURE 7. Elasmopus laminischia sp. nov., male paratype, Uchelbeluu Reef, Palau.