Caridina congoensis, Richard & Clark, 2009

Jasmine Richard & Paul F. Clark, 2009, African Caridina (Crustacea: Decapoda: Caridea: Atyidae): redescriptions of C. africana Kingsley, 1882, C. togoensis Hilgendorf, 1893, C. natalensis Bouvier, 1925 and C. roubaudi Bouvier, 1925 with descriptions of 14 new species, Zootaxa 1995, pp. 1-75 : 48-51

Caridina congoensis sp. nov.

( Figs. 24 , 25 )

Material examined. Holotype: ♂ Congo Paratypes: 3♂ Bakou, 12– 19.6.1984, in river, in total darkness, 30 m depth, coll. T. Montreille et al., pres. Dr. L. Deharveng, 2.1989, RMNH D 37639.

Description. Total length: 14–15 mm. Carapace length: 3.5–4 mm.

Rostrum ( Fig. 24a, b, c ): extending between middle of first to second segment of antennular peduncle. 1.4–1.5 mm in length. 0.4 × long as carapace. 13–16 teeth on dorsal margin arranged almost to tip. 3–5 postorbital teeth. 1–3 teeth on ventral margin leaving short distal end unarmed. Tip pointed. Formula (3–5) 13–16/ 1–3.

Antennular peduncle ( Fig. 24d ): 0.45–0.5 × carapace. Stylocerite 0.9–1 × length of basal segment. Anterolateral teeth of basal segment 0.4–0.45 × second segment. 11–12 segments bearing aesthetascs.

First pereiopod ( Fig. 25a ): dactylus 1–1.1 × palm of propodus. Chela 2–2.1 × long as broad. Carpus 1.5–1.6 × long as broad with anterior excavation.

Second pereiopod ( Fig. 25b ): dactylus 1.1–1.2 × long as palm of propodus. Chela 2.4–2.5 × long as broad. Carpus 5–5.5 × long as broad.

Third pereiopod ( Fig. 25c, d ): dactylus 1.7–1.8 × long as broad. Spines on dactylus varying from 4–5 (including terminal spines). Propodus 4.5–5 × long as dactylus and 7–8 × long as broad with 10–12 spines along posterior margin. Carpus 0.75–0.8 × long as propodus, with minute spines on inner margin. Merus 1.6–1.7 × carpus length. Merus with 2 spines on posterior margin.

Fifth pereiopod ( Fig. 25e, f ): dactylus 3–3.3 × long as broad with 50–55 spines arranged in comb-like fashion on inner margin. Propodus 10–11 × long as broad and 3.8–4 × long as dactylus with 16–18 spines along inner margin. Carpus 0. 5–0.6 × propodus length and with minute spines along inner margin. Merus 1.5–1.6 × carpus length, with 2 spines at posterior margin.

Setobranchs: 2 on all pereiopods.

First male pleopod ( Fig. 25g, h ): endopod long 0.6 × exopod length. Appendix interna absent. Several short stalked setae arranged along entire margin.

Second male pleopod ( Fig. 25i, j ): appendix masculina long, 2.1–2.2 × appendix interna. 0.5–0.55 × endopod.

Sixth abdominal somite: 0.4–0.5 × long as carapace.

Telson ( Fig. 25k, l ): 1.1 to 1.2 × long as sixth abdominal somite. Dorsal spines 5–6 pairs (including sub terminal spine). 1 pair of short lateral spines and 7 or 9 long sparsely plumose spines increasing in length towards centre, present at posterior margin of telson.

Uropod ( Fig. 25m, n ): 13–14 diaeresis spinules.

Preanal carina ( Fig. 25o ): Peg-like with bushy setae.

Remarks. Caridina congoensis sp. nov. is characterised by: the smaller size of the adult (14–15 mm); a short rostrum that is shorter than the first segment or extending to the middle of the second segment of the antennular peduncle; the stylocerite is 0.9–1.0 × the first segment, anterolateral tooth 0.40–0.45 × the second segment of the antennular peduncle; the dactylus of the third pereiopod bears 4–5 spines; the endopod of the first pleopod of male is longer, appendix masculina 2.1–2.2 × longer than the appendix interna; and the posterior margin of the telson bears long, sparsely plumose spines and the uropod diaeresis with 13–14 spinules. This combination of characters distinquishes C. congoensis sp. nov. from C. africana and C. togoensis .

At present, females of C. congoensis are not known and examination of more extensive collections from the type locality including females, would provide information on egg number and size, and add to the present findings.

Etymology. Named congoensis , after the Congo, the region from where the species is recorded.

Figures

FIGURE 24. Caridina congoensis sp. nov., RMNH D 37639, ♂1: a) Entire. ♂2: b) Anterior region of cephalothorax. ♂3: c) Anterior region of cephalothorax. ♂1: d) Antennular peduncle.

FIGURE 25. Caridina congoensis sp. nov., RMNH D 37639, ♂: a) First pereiopod; b) Second pereiopod; c) Third pereiopod; d) Dactylus of third pereiopod; e) Fifth pereiopod; f) Dactylus of fifth pereiopod; g) First pleopod; h) Endopod of first pleopod; i) Second pleopod; j) Appendix masculina; k) Telson; l) Posterior margin of telson; m) Uropod; n) Uropod diaeresis spinules; o) Preanal carina.