Elasmopus menurte J.L. Barnard, 1974

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 : 62

Elasmopus menurte J.L. Barnard

Figs. 1, 2

Elasmopus menurte J.L. Barnard, 1974: 21 , figs. 14, 15. Elasmopus ecuadorensis hawaiensis .–Appadoo & Steele, 1998:

639.

Material examined. 1 juvenile from mixture of red coralline algae and the alga Gracilaria salicornia, Balaclava (20°3.7'S 57°30.7'E), 10 Sep. 1998. 1♀ from the alga Enteromorpha flexuosa , Flic-en- Flac (20°16.5'S 57°21.7'E), 9 Nov. 1998. 1♀, 1 juv., from Gracilaria sp. , Souillac (20°31'S 57°30.7'E), 25 Mar. 1999. 333, 1♀, 2 juv., from mixture of the algae Digenia simplex , Laurencia papillosa , Centroceras clavulatum , Padina sp. and Gracilaria salicornia, Roches Noires (20°6.2'S 57°44.5'E), 9 Apr. 1999. 3♀♀ from mixture of Padina sp. and the alga Halimeda sp. , Grand Baie (20°0.5'S 57°34'E), 5 May 1999. 1♀ from Digenia simplex , Padina sp. and the alga Jania adherens, Roches Noires , 21 Jun. 1999. 333, 4♀♀, 6 juv., from mixture of the algae Laurencia papillosa , Padina sp. , Digenia simplex , Dictyota divaricata and Jania adherens, Trou D’eau Douce (20°14.5'S 57°47'E), 21 Jun. 1999. 13, 1 juv., from Digenia simplex , Padina sp. and Jania adherens, Roches Noires , 6 Aug. 1999. 233, 3♀♀ from Ulva lactuca, Palmar (20°13.5'S 57°48'E), 6 Aug. 1999. 13, 1♀ from the alga Sargassum sp. , La Cuvette (20°00'S 57°34.2'E), 12 Oct. 1999. 733, 28♀♀, 12 juv. from mixture of Digenia simplex , Padina sp. and globose brown algae, Roches Noires, 15 Oct. 1999. 1♀ from mixture of Padina sp. , Sargassum densifolium , the alga Pocockiella variegata and globose brown alga, Bain Boeuf (19°59'S 57°36'E), 13 Dec. 1999. 13, 4♀♀, from mixture of Padina sp. , Digenia simplex , Sargassum sp. , globose brown alga, Roches Noires, 16 Dec. 1999.

Description. Male: length 6.7 mm. Head, lateral cephalic lobes rounded, with subocular notch, eyes large and subround with ring of clear ommatidia surrounding a dark core. Antenna 1, peduncle article 1 with robust seta and a few slender setae on posterior margin; article 2 subequal to 1; article 3, 0.6× length of article 1; accessory flagellum 3- articulate, the third article vestigial; primary flagellum 21- articulate. Antenna 2, peduncle articles 4 and 5 setose; article 5, 0.8× length of article 4; flagellum 7-articulate. Mandible, palp article 2, 1.5× article 1, with several medial and several distal setae; article 3 falcate, subequal to article 2, with comb row of setae, 2 long apical setae and 2 shorter setae on anterior margin. Maxilla 1, inner plate with 2 terminal plumose setae and several fine setae on inner margin. Labium, with rounded mandibular lobes; outer plate with blunt stout seta on inner margin. Maxilliped, palp article 3 with a small distal protuberance. Gnathopod 1, coxa produced anterodistally, rounded, 1.6× as long as broad, distal margin with very short setae; basis twice as long as broad; propodus slightly longer than carpus, with 2 distinct semicircular comb rows of setae on inner medial face, palm defined by a robust seta. Gnathopod 2, coxa about 1.5× as long as broad, distal margin with short setae; basis 3× as long as broad; merus posterodistal margin weakly produced, carpus twice as broad as long; propodus about 5× as long as carpus, posterior margin densely setose, distal part of palm with robust setae on a shallow protuberance; inner medial face of propodus with a small ridge carrying robust setae; dactylus about half length of propodus, inner margin weakly crenulate. Pereopods 3–4, coxa distal margin with short setae; propodus 1.2× as long as carpus, posterodistal margin with 1 long and 1 short straight robust seta; dactylus subdistally constricted. Pereopods 5–7, ba sis weakly serrate with short setae. Pereopods 5–6, basis posterior margin weakly convex, posterodistal margin produced into a rounded lobe. Pereopod 7, basis posterior margin strongly convex, posterodistal corner subtriangular. Epimera 1–3, with weakly developed posterodistal tooth, distal margin with a single row of 1 to 3 robust setae. Epimeron 3 subquadrate. Pleon and urosomite 1, with short fine dorsal setae. Urosomite 1, with a low, triangular, dorsal hump. Uropod 1, peduncle 1.2× length of inner ramus; outer ramus subequal in length to inner ramus. Uropod 2, peduncle subequal to inner ramus; outer ramus 1.2× length of inner ramus. Uropod 3, peduncle subequal to inner ramus; outer ramus 1.2× length of inner ramus; both rami with robust setae on lateral margin; outer ramus truncate, with terminal robust setae and 1 long slender seta. Telson, cleft to about 75% its length; telsonic lobes notched and with two to three robust distal setae.

Female sexually dimorphic characters: length, 4.7 mm (with oostegites). Gnathopod 1, similar to that of male but basis more slender, 3× as long as broad; propodus subequal to carpus. Gnathopod 2, coxa subquadrate 1.6× as long as broad, posterior margin with short robust setae; basis 3× as long as broad; propodus 1.8× as long as carpus, twice as long as broad, posterior margin with long slender setae, palmar border with stout robust setae interspersed between long slender setae.

Variation. The telson apices are asymmetrical (inner tooth more produced than the outer) in large males (e.g., 6.7 mm) but symmetrical in juveniles (e.g., 4.3 mm).

Remarks. This is the first record of E. menurte from Mauritius. Present material agrees closely with the description of J.L. Barnard (1974). The species is distinguished from all other Elasmopus species in Mauritius by the following characters in combination: the short setae on the coxal plates of gnathopods 1 and 2, the presence of robust setae on a protuberance on the palm of the male gnathopod 2, the simple robust setae on the posterodistal margin of the propodus of pereopods 3 and 4, the shape of the telson and the presence of a small hump on urosomite 1.

Type locality. Western Australia, west of Bunker Bay, Cape Naturaliste .

Distribution. Western Australia; Mauritius.