Cerapus Say, 1817

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 : 84-85

Cerapus Say

Cerapus Say, 1817: 49 .

Baracuma Barnard & Drummond, 1981: 31 .

Diagnosis. Antenna 1: peduncular article 1 with proximoventral swelling; without accessory flagellum. Mandibles: left incisor with 6 teeth; left lacinia mobilis with 5 teeth; left accessory setal row with 2­ 3 broad robust setae and 2-3 intermediate plumose setae; right incisor with 5-6 teeth; right lacinia mobilis with 1 large tooth and a minutely denticulate margin; right accessory setal row with 2 setae and 2 plumose setae; mandibular palp elongate, slender. Maxilla 1: outer plates each with 10 setal-teeth. Gnathopod 2: carpochelate in male, subchelate in 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 1-2 small accessory spines. Peraeopod 6: dactylus with large unguis and 2 small accessory spines. Peraeopod 7: dactylus with large unguis and 1-2 small accessory spines. Pleopod 2: inner ramus reduced, 1­ articulate. Pleopod 3: inner ramus reduced, I-articulate ramus. Uropod 2 with one ramus. Uropod 3 with one vestigial ramus bearing small recurved spines.

Type species. Cerapus tubularis Say, 1817 .

Species composition. Cerapus currently contains 11 species: C. 'alquirtus (Barnard & Drummond, 1981); C. benthophilus Thomas & Heard, 1979; Cerapus calamicola (Giles, 1885) ; C. cudjoe Lowry & Thomas, 1991 ; C. erae, Bulycheva, 1952; C. flindersi Stebbing, 1888; C. longirostris Shen, 1936; C. micronesicus Myers, 1995; C. oceanicus Lowry, 1985; C. pacificus Lowry, 1985; and C. tubularis Say, 1817 . Cerapus abditus Templeton, 1836 is considered to be an unrecognisable species.

Remarks. Lowry & Berents (1989) showed that the elongation of peraeonite 5 in the female is not a generic character among the Cerapus clade. They maintained Baracuma based on the sternal keel. Budnikova (19,89) has synonymised Baracuma with Cerapus . 佴戮繲 possible generic differences between these tightly 'defined species are: in C. erae, C. longirostris and C. oceanicus the dactyli of peraeopod 5 have two small accessory spines instead of one; and in C. alquirtus and C. oceanicus there is only one accessory spine on the dactylus of peraeopod 7.