Australian Amphipoda: Eusiridae

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

Rhachotropis sp.

Type material. HOLOTYPE: male, 4.8 mm, AM P27294.

Type locality. east of Lady Elliot Island, Queensland (24º00'S 153º06'E), dredged from 500 m depth on fine grey ooze, sand with Pteropod shells.

Description. Based on holotype male, AM P27294. Head rostrum present, long; eyes present, eyes round. Body dorsally carinate. Antenna 1 shorter than antenna 2; accessory flagellum absent. Mandible molar conical, setose. Lower lip inner lobes present; outer lobes with broad gap. Maxilla 1 inner plate apically setose. Maxilla 2 inner plate much broader than outer; inner plate slender medial setae few or absent, without oblique row of slender setae.

Peraeon. Gnathopod 1 subchelate; subequal to gnathopod 2; coxa strongly produced anteroventrally; carpus not cantilevered, shorter than propodus, posterodistally lobed; propodus with robust setae along posterior margin (adults); dactylus narrowing distally, apically acute or subacute. Gnathopod 2 not sexually dimorphic. Gnathopod 2 subchelate; carpus not cantilevered, posterodistally lobed, shorter than propodus; propodus with robust setae along posterior margin (adults); dactylus narrowing distally, apically acute or subacute. Peraeopods 3-4 propodus simple, with distal slender setae.

Pleon. Pleonites 2 tricatinate. Epimeron 3 posteroventral margin serrate, corner subacute. Uropod 1 outer ramus shorter than inner. Uropod 3 peduncle with dorsal robust setae; rami subequal in length. Telson cleft, without large apical robust setae.

Habitat. Marine; dredged from 500 m depth on fine grey ooze, sand with Pteropod shells.

Depth zones. Continental slope (500 m).

Remarks. Rhachotropis sp. keys out to R. inflatus in J.L. Barnard (1957), but it differs from that species in the dorsal ornamentation of the pleonite and urosomite segments. Specimens of this species had the gnathopods reversed at the carpus, similar to species of trischizostomatid lysianassoids.

Distribution. Queensland: east of Lady Elliott Island (AM).

Geographic areas. North-eastern Australia.

Cite this publication as: 'J.K. Lowry, P.B Berents & R.T. Springthorpe (2000 onwards). Australian Amphipoda: Eusiridae. Version: 2 October 2000. https://crustacea.net'.