Elasmopus pectenicrus (Bate)

Chandani Appadoo, 2003, The Genus Elasmopus (Crustacea: Amphipoda: Melitidae) from Mauritius (Indian Ocean) with Description of Five New Species, Records of the Australian Museum 55, pp. 61-84 : 65-67

Elasmopus pectenicrus (Bate)

Fig. 4

Maera pectenicrus Bate, 1862: 192 , pl. 34(8).

Elasmopus pectenicrus .–K.H. Barnard, 1916: 197, pl. 28(33).– K.H. Barnard, 1940: 461.– Schellenberg, 1928: 647; 1938: 55.– Shoemaker, 1935: 238.– Pirlot, 1936: 312.– Ruffo, 1938: 162; 1969: 28.– Reid, 1951: 236, fig. 32.–J.L. Barnard, 1955: 8, fig. 4.–J.L. Barnard, 1970: 126, figs. 73, 74.– Nayar, 1959: 27, pl. 9(20–35).– Sivaprakasam, 1966: 103.– Griffiths, 1974a: 235; 1974b: 289; 1975: 121.– Ledoyer, 1982: 475, figs. 179, 180a.– Appadoo & Steele, 1998: 639.

Material examined. 13 from the alga Centroceras clavulatum, la Cuvette (20°00'S 57°34.2'E), 28 Aug. 1999. 333 from mixture of the algae Sargassum sp. , Ulva reticulata , Digenia simplex and Centroceras clavulatum, La Cuvette , 25 Jan. 2000.

Description. Male: length, 6.2 mm. Head, with subocular notch; eyes oval, with ring of clear ommatidia and a dark central core. Antenna 1, peduncle article 1 with few setae; article 2 subequal to 1; article 3, 0.7× article 1; accessory flagellum 2-articulate; primary flagellum 20-articulate. Antenna 2, peduncle articles 4 and 5 setose; article 5 slightly longer than article 4, flagellum 10-articulate. Mandible, palp article 2 twice as long as article 1, with setae on medial and lateral surfaces; article 3 falcate, 1.2× article 2, with comb-row of setae and 4 long apical setae. Maxilla 1, inner plate with 2 terminal plumose setae and several fine setae on inner margin. Labium, mandibular lobes rounded; outer plate with a small blunt stout seta on inner margin. Maxilliped, palp article 3 with a small protuberance at distal end. Gnathopod 1, coxa expanded anterodistally, 1.2× as long as broad, distal margin with very short setae; basis almost 3× as long as broad, posterior margin with patches of long setae; carpus 1.2× length of propodus with dense medial rows of long pectinate setae; propodus 1.5× as long as broad, anterior margin with 6 groups of setae, palm defined by a short robust seta. Gnathopod 2, coxa 1.2× as long as broad, distal margin with short setae; basis 3.4× as long as broad; carpus reduced, about 2.2× as broad as long; propodus 6× as long as carpus, palm short, almost transverse, posterior margin sinuous, with dense pectinate setae along almost entire length; dactylus slender, evenly curved. reaching about half length of propodus. Pereopods 3–4, basis slender, 4× as long as broad; propodus posterodistal margin with 1 long and 1 short straight robust seta; dactylus constricted subdistally. Pereopod 5, basis subovate, posterior margin weakly crenulate with short setae. Pereopod 6, basis posterior margin convex, produced into a subtriangular distal lobe, posterodistal margin deeply castelloserrate. Pereopod 7, basis posterior margin strongly convex, weakly castelloserrate with short setae. Epimera 1–2, with small posterodistal tooth. Epimeron 3, posterodistal margin weakly serrate, distal margin with row of robust setae in groups of 1– 3. Uropod 1, outer ramus 0.7× length of peduncle and slightly shorter than inner ramus. Uropod 2, peduncle subequal to outer ramus; outer ramus 0.8× inner ramus. Uropod 3, peduncle subequal to inner ramus; inner ramus 0.7× length of outer ramus; rami truncate with robust setae on lateral margins and on apices. Telson, cleft 75% its length, apically truncate with 4 robust setae on each lobe.

Female. Not found.

Remarks. This species can be distinguished from the other Elasmopus species in Mauritius by the following characters in combination: short setae on coxae of gnathopods 1 and 2, the shape of gnathopod 2 with a long slender dactylus, the castelloserrate and triangular process on the basis of pereopod 6 and the truncate and spinous telson.

Type locality. New Guinea (see Bate, 1862) .

Distribution. West Africa, South Africa, Madagascar, Mauritius, Red Sea, India, Indonesia, New Guinea, Australia, Hawaii, Caribbean.