Bathypoma, Lowry & Berents, 1996

Lowry, J. K. & Berents, Penelope B., 1996, The Ericthonius group, a new perpective on an old problem (Crustacea: Amphipoda: Corophioidea), Records of the Australian Museum 48 (1), pp. 75-109 : 84

Bathypoma n.gen.

Diagnosis. Antenna 1: peduncular article 1 with dorsodistal flange partially overlapping article 2 and produced medially to form a operculum; without accessory flagellum. Mandibles: left incisor with 5 teeth; left lacinia mobilis with 4 teeth; left accessory setal row with 3 broad robust setae and 3 intermediate plumose setae; right incisor with 5 teeth; right lacinia mobilis with 1 small tooth and a minutely denticulate margin; right accessory setal row with 2 robust setae and 2 plumose setae; mandibular palp short, broad. Maxilla 1: outer plates each with 9 setal-teeth. Gnathopod 2: subchelate in male and female. Peraeopods 3 to 7: dactyli all directed posteriorly. Peraeopod 4: merus short, not expanded posteriorly. Peraeopod 5: coxa in female larger than in male, without fringe of long setae; dactylus with large unguis and 2 small accessory spines. Peraeopod 6: dactylus with large unguis and 2 small accessory spines. Peraeopod 7: dactylus with large unguis and 2 small accessory spines. Pleopod 2: inner ramus reduced, I-articulate. Pleopod 3: uniramous, I-articulate ramus. Uropod 2 with one ramus. Uropod 3 with one vestigial ramus bearing small recurved spines.

Type species. Bathypoma enigma n.sp.

Species composition. Bathypoma is monotypic.

Etymology. The name Bathypoma is derived from the Greek "poma" for lid and refers to the peduncle of antenna 1 which forms a lid to seal the tube, and "bathys" from the Greek for deep which refers to the depth distribution of the genus.

Remarks. Bathypoma is unique because the male has a subchelate gnathopod 2. The complex set of characters which makes up gnathopod 2 is considered important because the morphology of the carpus, propodus and dactylus is completely different from that of the carpochelate gnathopod of other males in the Cerapus clade. The major muscle mass of the gnathopod occurs in the propodus rather than carpus which indicates that the gnathopod functions in a different way. The overall morphology of the gnathopod does not suggest a neotenic condition, but it is remarkably similar to gnathopods in the genus Unciola .