Caribboecetes, Just, 1983

Just, Jean, 1998, Siphonoecetinae (Crustacea: Amphipoda: Ischyroceridae) 7: Australian Concholestids, Ambicholestes n. gen., with a Description of Six New Species, and a New, Restricted Diagnosis for Caribboecetes Just, 1983, Records of the Australian Museum 50 (1), pp. 27-54 : 28-29

Review of Caribboecetes

Caribboecetes Just, 1983 , differs from other concholestids by having a short, flattened inner ramus on uropod 1 and no ramus on uropod 3. Concholestes Giles, 1888 has a long and cylindrical inner ramus on uropod 1 and no ramus on uropod 3, while Africoecetes Just, 1983 has one ramus on uropod 3. Following the discovery of several new

concholestids from Australia and a re-evaluation of the Caribboecetes species described by Just (1983, 1984a) it has become clear that Caribboecetes must be divided into two groups based primarily on the structure of the lower lip and the setation on pereopod 7. Caribboecetes barbadensis (type-species of the genus), c. jenikarpae , and C. intermedius have the inner lobes of the lower lip simple, more or less ovoid, while C. crassicornis , C. magellani , and C. squamiferus have uniquely and complexly lobate inner lobes ( Fig. 2 ) with a proximolateral backward curving projection on each lobe and the proximal lobe margin produced and set at an angle of up to 45 degrees with the inner lobe plane. The three last mentioned species have a midlateral, longitudinal row of setae on article 2 of pereopod 7 in addition to the normal marginal setae. The densely setose anterior lateral surfaces of coxal plate 7 and article 2 of pereopod 7 in C. jenikarpae are considered independently derived autapomorphisms.

On this basis a new genus, Ambicholestes , is established for C. crassicornis , C. magellani , C. squamiferus and the Australian concholestids described below. Diagnostic differences between Caribboecetes and Ambicholestes are summarised in Table 1 (p. 53).

The structure of the lower lip in Caribboecetes pterycornis is not known (lost during original dissection). In spite of several autapomorphic attributes, which set this species apart from other Caribboecetes , I tentatively retain it in that genus on account of the lack of a midlateral row of setae on article 2 of pereopod 7.

Figures

Fig. 2. Lower lip of selected concholestid Siphonoecetinae. A, Concholestes omani Just, 1987; B, Africoecetes armatus (Griffiths, 1974); C, Caribboecetes barbadensis Just, 1983; D, Caribboecetes intermedius Just, 1984; E, Caribboecetes jenikarpae Just, 1984; F, Ambicholestes crassicornis (Just, 1984, n. comb.); G, Ambicholestes squamiferus (Just, 1984, n. comb.); H, Ambicholestes berentsae n.sp., lateral view. Not to scale