Caridina lumilympha, Richard & Clark, 2010

Richard, Jasmine & Clark, Paul F., 2010, Caridina H. Milne Edwards, 1837 (Crustacea: Decapoda: Caridea: Atyoidea: Atyidae) - freshwater shrimps from eastern and southern Africa *, Zootaxa 2372 (1), pp. 305-337 : 328-331

Caridina lumilympha sp. nov.

( Figs. 12–13 )

Material examined. Types: holotype male, Kenya Lumi River , pres. H. Copley, NHM 1939.6.6.1 ; paratypes 1 male, 4 females, 1 juv., 1 damaged specimen with abdomen only, NHM 1939.6.6.2–4.

Description. Total length: 20–30 mm. Carapace length: 4–5 mm.

Rostrum ( Figs. 12a–c ): Longer than antennal scale. 4.5–6 mm in length. 1.1–1.4 as long as carapace. 16–25 teeth arranged proximally leaving 0.5–0.6 of distal dorsal margin unarmed. Unarmed distal margin not interrupted by teeth. 2–3 post-orbital teeth present. 18–25 teeth are arranged from proximal end to tip on ventral margin. Formula (2–3) 16–25/18–25. Tip bifid or acute.

Antennular peduncle ( Fig. 12d ): 0.8–0.9 times as long as carapace. Stylocerite 0.7–0.8 of length of basal segment. Anterolateral teeth of basal segment 0.3–0.35 as long as second segment. 10–15 segments bearing aesthetascs.

First pereiopod ( Fig. 13a ): dactylus 1.1–1.2 of palm of propodus. Chela 2.50–2.7 as long as wide. Carpus 2.4–2.8 as long as wide with anterior excavation.

Second pereiopod ( Fig. 13b ): dactylus 1.1–1.3 as long as palm of propodus. Chela 3–3.3 as long as wide. Carpus 4.5–4.8 as long as wide. Brush-like setae at tip of chelae of first and second pereiopod.

Third pereiopod ( Figs. 13c–d ): dactylus 3–3.25 as long as wide. Spines on dactylus 9–12 (including terminal spines). Propodus 4.4–4.7 as long as dactylus and 12–13 as long as wide with 11–14 spines along inner margin. Carpus 0.6–0.7 as long as propodus, with 1 large spine and minute spines on inner margin. Merus 1.5–1.6 of carpus length. Merus with 3 large spines along posterior margin.

Fifth pereiopod ( Figs. 13e–f ): dactylus 4.3–4.7 as long as wide with 45–55 spines in comb-like arrangement on inner margin. Propodus 14–15 as long as wide and 4.5–4.7 as long as dactylus with 12–15 spines along posterior margin. Carpus 0.5–0.6 of propodus length and with minute spines along inner margin. Merus 1.7–1.9 of carpus length with 2 large spines and fine setae along posterior margin.

Setobranch: 2 setae on each pereiopod.

First male pleopod ( Figs. 13g –h ): endopod 0.22 of exopod length. Long setae present at tip of endopod turned down giving cobra head appearance. No appendix interna present.

First female pleopod ( Fig. 13i ): endopod 0.4–0.5 as long as exopod.

Second male pleopod ( Figs. 13j–k ): appendix masculina 1.5 as long as appendix interna, 0.3 of endopod length.

Sixth abdominal somite: 0.8–0.9 as long as carapace.

Telson ( Figs. 13l–n ): 1.0–1.1 as long as 6 th abdominal somite. Tapering distally. Dorsal spines 4–5 pairs (including sub terminal spine). 1 pair of lateral spines and 2–3 pairs or 7 sparsely plumose spines that increase in length towards centre, present at rounded posterior margin.

Uropod ( Fig. 13o ): 9–12 diaeresis spinules.

Preanal carina ( Fig. 13p ): armed with a spine.

Etymology. Named for the Lumi River; lympha from the Latin meaning clear river water.

Distribution. Known only from the type locality in Kenya.

Remarks. Caridina lumilympha sp. nov. is distinct from all African congeners in possessing a longer rostrum with dorsal teeth only arranged along the proximal end leaving the distal part unarmed, teeth arranged from the proximal end to the tip on the ventral rostral margin, endopod of the first male pleopod “cobra head like” with long setae at the tip and not bearing an appendix interna, posterior margin of the telson rounded bearing one pair of lateral spines and 2 or 3 pairs or 7 sparsely plumose spines that are increasing in length towards the centre.

Caridina lumilympha is similar to C. nilotica in having a rostrum longer than the antennal scale and in its proximal arrangement of teeth on the dorsal rostral margin. However, C. lumilympha differs from C. nilotica by the rounded posterior margin of telson where the inner spines increase in length towards the centre. In C. nilotica the posterior margin of the telson is mostly flat or slightly triangular, the spines on the posterior margin of the telson are mostly 1 pair of short spines and when more than 1 pair is present the outer pair is longer than the inner.

Examination of more samples including from the type locality with ovigerous females might provide differentiation based on the egg size. The distal unarmed margin of the rostrum is not interrupted in all the specimens examined. This character should be confirmed with more samples.

Figures

FIGURE 12. Caridina lumilympha sp. nov., NHM 1939.6. 1–4: a, habitus; b, anterior region of cephalothorax; c, anterior region of cephalothorax; d, antennular peduncle. a–c, female; d, male.

FIGURE 13. Caridina lumilympha sp. nov., NHM 1939. 6. 1–4: a, first pereiopod; b, second pereiopod; c, third pereiopod; d, dactylus of third pereiopod; e, fifth pereiopod; f, dactylus of fifth pereiopod; g, first male pleopod; h, endopod of first male pleopod; i, first female pleopod; j, second male pleopod; k, appendix masculina; l, telson; m, posterior margin of telson, n, posterior margin telson; o, uropod diaeresis spinules; p, preanal carina. a–h, j–m, male; i, n– p female.