Australian Amphipoda: Melitae

J.K. Lowry, P.B Berents & R.T. Springthorpe

Elasmopus crenulatus Berents, 1983

Elasmopus crenulatus Berents, 1983: 113, figs 10-12.

Type material. HOLOTYPE: male, 3.5 mm AM P30095; PARATYPES: female, 4.8 mm, AM P30096; 2 specimens, AM P30097; 2 specimens, AM P30098; female, 3.8 mm, USNM 190702; male, 3.3 mm, USNM 190703; 3 specimens, BMNH 1981;623:3.

Type locality. Chinaman's Ridge, Watson's Bay, Lizard Island, Great Barrier Reef, (14º 40'S 145º 27'E), reef rock, 7 m depth.

Description. Based on Berents, 1983: 113, figs 10-12. Head with anteroventral notch or slit. Antenna 1 longer than antenna 2; peduncular article 1 not geniculate with article 2, subequal in length to article 2, with 1 robust seta on posterior margin; flagellum with 8 articles; accessory flagellum with 2 articles. Article 4 subequal to article 5; antenna 2 flagellum with 6 articles. Mandible palp present, well developed, article 3 strongly falcate, setose along concave medial margin, longer than article 1, article 2 longer than article 3, article 1 not produced, shorter than article 2, about twice as long as broad. Maxilla 1 inner plate with setae mainly terminal.

Pereon. Gnathopod 1 not sexually dimorphic; coxa anteroventral corner produced, rounded, coxa posteroventral corner notch absent; merus without posterodistal tooth; carpus about 2 x as long as broad; propodus without anterodistal projection, posterodistal margin not swollen, palm acute, straight, defined by posterodistal corner, defined by posterodistal robust setae. Gnathopod 2 sexually dimorphic; subchelate; left and right gnathopods subequal in size; coxa posteroventral corner notch absent; merus with sharp posteroventral tooth; carpus compressed; propodus without medial depression, setose, palm acute, straight, sculptured, with group of anterodistal robust setae, without posterodistal robust setae, without posteroventral corner; dactylus closing along palm, not reaching end of palm, apically acute/subacute. Peraeopod 5 basis posteroventral corner narrowly rounded or subquadrate. Peraeopod 6 coxa anterior lobe ventral margin slightly produced, truncated. Peraeopod 6 basis posterior margin straight. Peraeopod 6 propodus not expanded posterodistally. Peraeopod 7 basis posterior margin convex. Peraeopod 7 basis with posterior margin castelloserrate, posteroventral corner broadly rounded. Peraeopod 7 propodus not expanded posterodistally.

Pleon. Pleonite 1 without dorsal serrations, without dorsodistal spines, not dorsally bicarinate. Pleonite 2 without dorsal serrations, without dorsodistal spines, not dorsally bicarinate. Pleonite 3 without dorsal serrations, without dorsodistal spines, dorsally smooth. Epimeron 1 anteroventral corner without curved spine. Epimera 1-2 posteroventral margin without spines above posteroventral corner. Epimeron 3 posterior margin smooth, posteroventral corner with small acute spine, posteroventral margin smooth. Urosomite 1 without dorsal carina, without a small dorsal hump, without dorsal serrations, without spines or gape, not dorsally bicarinate. Urosomite 1 without posterodorsal spine. Urosomite 2 posterior margin smooth, without dorsolateral robust setae. Urosomite 3 without dorsal robust setae. Uropod 1 peduncle without distoventral spur. Uropod 3 subequal or slightly exceeding length of uropods 1 and 2; inner ramus shorter than outer ramus; outer ramus short (shorter than or subequal to peducle), 1-articulate. Telson cleft. Telson without robust setae on inner margins. Telson each lobe with 3 or more apical/subapical robust setae, apical conical extension reaching scarcely one third along longest seta.

Habitat. Marine; living on reef rock, dead coral and encrusting algae from 4 to 7 m depth.

Depth zone. Littoral.

Distribution. Queensland: Lizard Island, Great Barrier Reef (Berents, 1983). Western Australia: Cocos (Keeling) Islands, Indian Ocean (Berents, 1983).

Australian geographic areas. North-eastern Australia, or North-western Australia.

(Variant) Female (sexually dimorphic characters).

Not known.

Pereon. Gnathopod 2 convex, smooth, without robust setae, defined by posterodistal robust setae; reaching end of palm.

Pleon. Telson each lobe with 2 apical/subapical robust setae or each lobe with 3 or more apical/subapical robust setae.

Cite this publication as: 'J.K. Lowry, P.B Berents & R.T. Springthorpe (2000 onwards). Australian Amphipoda: Melitae Descriptions, Illustrations, Identification and Information Retrieval. Version: 2 October 2000.'.