Australian Amphipoda: Melitae

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

Ceradocus (Denticeradocus) hawaiensis J.L. Barnard, 1955

Ceradocus hawaiensis J.L. Barnard, 1955: 5, figs 2-3. --J.L. Barnard, 1970: 115, fig. 65. --J.L. Barnard, 1971: 70, fig. 41. --Ledoyer, 1972: 207, figs 30-31. Ledoyer, 1978: 266. --Ledoyer, 1982: 436, fig. 163. --Barnard & Barnard, 1983: 615.

Ceradocus (Denticeradocus) hawaiensis. --Berents, 1983: 103, fig. 2.

Type material. HOLOTYPE: male, 4 mm, BMH 6032. PARATYPES: male, 5 mm, female, 5 mm.

Type locality. Hanauma Bay, Oahu, Hawaii Islands.

Description. Based on J.L. Barnard, 1955: 5, figs 2-3. Head lateral cephalic lobes broad, truncated, with anteroventral notch or slit, anteroventral corner with blunt tooth or subquadrate. Antenna 1 longer than antenna 2; peduncular article 1 not geniculate with article 2, subequal in length to article 2, with 2 robust setae along posterior margin; flagellum with 12-13 articles; accessory flagellum with 6 articles. Article 4 longer than article 5; antenna 2 flagellum with 9-10 articles. Mandible palp present, well developed, article 3 cone-like, setose on distomedial margin, subequal to article 1, article 2 longer than article 3, article 1 produced distally, shorter than article 2, about twice as long as broad. Maxilla 1 inner plate setose along entire inner margin.

Pereon. Gnathopod 1 not sexually dimorphic; coxa anteroventral corner produced, acute, 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, convex, defined by posterodistal corner. Gnathopod 2 sexually dimorphic; subchelate; left and right gnathopods unequal in size; coxa posteroventral corner notch absent; compressed; palm angle nearly transverse, straight, defined by posterodistal tooth, without robust setae; dactylus apically blunt; (smaller) merus with sharp posterventral tooth; long; palm convex, defined by posteroventral tooth. Peraeopod 5 basis posterior margin straight. Peraeopod 5 basis posteroventral corner with acute or subacute process. Peraeopod 6 coxa anterior lobe ventral margin not produced ventrally. Peraeopod 6 basis posterior margin straight. Peraeopod 6 basis posteroventral corner with acute or subacute process. Peraeopod 6 propodus not expanded posterodistally. Peraeopod 7 basis posterior margin straight. Peraeopod 7 basis with posterior margin smooth or minutely castelloserrate, posteroventral corner with acute or subacute process. Peraeopod 7 propodus not expanded posterodistally.

Pleon. Pleonite 1 with dorsal serrations, without dorsodistal spines, not dorsally bicarinate. Pleonite 2 with dorsal serrations, without dorsodistal spines, not dorsally bicarinate. Pleonite 3 with 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 serrate, posteroventral corner with strongly produced acute spine, posteroventral margin smooth or serrate. Urosomite 1 without dorsal carina, without a small dorsal hump, without dorsal serrations, with spines at midline, no conspicuous medial gape, not dorsally bicarinate. Urosomite 1 without posterodorsal spine. Urosomite 2 posterior margin with dorsal midline spine, without dorsolateral robust setae. Urosomite 3 without dorsal robust setae. Uropod 1 peduncle with basofacial robust seta, without distoventral spur. Uropod 3 exceeding uropods 1 and 2; inner ramus subequal in length to outer ramus; outer ramus medium length (1.1 to about 1.5 x longer than peducle), 1-articulate. Telson cleft. Telson without robust setae on inner margins. Telson each lobe with 2 apical/subapical robust setae, apical conical extension reaching scarcely one third along longest seta.

Habitat. Marine; living commersally with the hermit crab Dardanus megistos (according to Berents, 1983).

Depth zone. Littoral.

Remarks. The material of C. hawaiensis which Ledoyer (1972; 1978; 1982) recorded from Madagascar and Mauritius and which Berents (1983) recorded from north-eastern Australia appears to be different from the populations of C. hawaiensis described by J.L. Barnard (1955) from Hawaii. The palmar sculpturing on the larger gnathopod 2 is grosser, the posterior margin of epimeron 2 has minute serrations above the posteroventral corner. The telson has twice as many apical robust setae in the western Indian Ocean population, but not the Australian population. These are small, but significant differences which may indicate a closely related, but undescribed species in Australia and the western Indian Ocean.

Distribution. Queensland: Heron Island, Great Barrier Reef (Berents, 1983).

Extrinsic distribution. Hawaiian Islands; Madagascar; Mauritius.

Australian geographic areas. North-eastern Australia.

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. https://crustacea.net'.