Caridina amnicolizambezi, 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 : 45-48

Caridina amnicolizambezi sp. nov.

( Figs. 22 , 23 )

Material examined. Holotype: ♀ ovig. Angola Rio Lucoge, branch of the Chicapu River, 7°36'S 20°31'E, 4.1964, coll. A. de Barros Machado, no. 6508. Paratypes: Rio Lucoge, branch of the Chicapu River, 7°36'S 20°31'E, 4.1964, coll. A. de Barros Machado, no. 6508. RMNH D 24469, 3♂, 20♀ ovig., 38♀; SE Angola, Rio Longa, tributary of the Zambesi, received 3.1963, pres. R. Bott, no. 4473, RMNH D 18639, 10♂, 9♀. Zambia Lake Tanganyika, Chilanga, coll. & pres. Dr. R. Huddart, 1971, NHM 2007.735–744, 3♂, 20♀.

Description. Total length: 15–30 mm. Carapace length: 3–4 mm.

Rostrum ( Fig. 22a, b, c, d ): straight, or tip turned up, tapering towards tip giving bulged appearnece subterminally; short, mostly reaching end of first segment of antennular peduncle or extending up to middle of third segment of antennular peduncle. 1.60–3.35 mm in length. 0.50–0.75 × long as carapace. 15–28 (mostly 20–25) teeth on dorsal margin arranged up to tip or with short unarmed distal end. 1–5 post-orbital teeth. 0–10 (mostly 2–8) teeth on ventral margin to tip or with short distal unarmed end. Tip pointed. Formula (1–5) 15–28/0–10, mostly (3–4) 20–25/2–8.

Antennular peduncle ( Fig. 22e ): 0.7–0.8 × carapace. Stylocerite 0.6–0.7 × length of basal segment. Anterolateral teeth of basal segment 0.25–0.35 × second segment. 5–6 segments bearing aesthetascs.

First pereiopod ( Fig. 23a ): dactylus 1.1–1.4 × palm of propodus. Chela 2.8–3.2 × long as broad. Carpus 2.4–2.7 × long as broad, almost no anterior excavation, anterior end flat.

Second pereiopod ( Fig. 23b ): dactylus 1.1–1.3 × long as palm of propodus. Chela 3.7–4.5 × long as broad. Carpus 5–6 × long as broad.

Third pereiopod ( Fig. 23c, d ): dactylus 4.2–4.6 × long as broad. Spines on dactylus varied from 9–14 (including terminal spines), mostly 11–13. Propodus 2.5–3.5 × long as dactylus and 11–12 × long as broad with 10–15 spines arranged along posterior margin. Carpus 0.5–0.7 × long as propodus, with minute spines on inner margin. Merus 1.5–1.8 × carpus length. Merus with 5 spines on posterior margin.

Fifth pereiopod ( Fig. 23e, f ): dactylus 4.5–5.9 × long as broad with 30–40 spines arranged in comb-like fashion on inner margin. Propodus 12–14 × long as broad and 2.5–3 × long as dactylus with 7–14 spines arranged along inner margin. Carpus 0.4–0.6 × propodus length and with minute spines along inner margin. Merus 1.4–1.7 × carpus length, with 2 spines at posterior margin.

Setobranchs: 2 on all pereiopods.

First male pleopod ( Fig. 23g, h ): endopod 0.3–0.4 × exopod length. Appendix interna absent. Short stalked setae arranged uniformly along entire margin.

First female pleopod ( Fig. 23i ): endopod 0.5–0.7 × long as exopod.

Eggs ( Fig. 23j ): 15–20, 1.2–1.3 × 0.7–0.9 mm in size.

Second male pleopod ( Fig. 23k, l, m, n ): length of appendix masculina varying. 1.0–1.1 × appendix interna, in specimens from Angola. In specimens from Lake Tanganyika, ( Fig. 22m ) longer, 1.5–1.6 × appendix interna, 0.2–0.33 × endopod.

Sixth abdominal somite: 0.6–0.7 × long as carapace.

Telson ( Fig. 22o, p ): 1.0 to 1.1 × long as sixth abdominal somite. 3 or 4 pairs of dorsal spines (including subterminal spine). 1 pair of plain lateral spines and 3 or 4 pairs of stalked plumose process present at posterior margin.

Uropod ( Fig. 23q, r ): 7–10 diaeresis spinules.

Preanal carina ( Fig. 23s ): unarmed.

Remarks. Caridina amnicolizambezi sp. nov. has the following distinctive characters: a shorter rostrum always with a pointed tip, turned upwards or straight with a slight bulge subterminally giving a spindle shape appearance; 15–28, mostly 20–25 teeth on dorsal margin of the rostrum, mainly arranged to the tip, rarely with a short distal unarmed margin; 0–10 ventral teeth (mostly 2–8) arranged with or without a short unarmed distal margin; the chelae are slender on the first and second pereiopods; the carpus of the first pereiopod has a flat anterior margin with almost no excavation; the dactylus of third pereiopod has 9–14 spines (including the terminal spine) (usually 11–13) and that of the fifth has 30–40 spines.

Ovigerous females carry 15– 20 eggs, 1.2–1.3 × 0.7–0.9 mm in size. The appendix masculina is either short being 1.0–1.1 × the appendix interna, or 1.5–1.6 × appendix interna. All of these characters are unique to Caridina amnicolizambezi sp. nov. It is similar to C. togoensis in having 3 or 4 pairs of stalked plumose processes on the posterior margin of the telson.

Etymology. The name amnicolizambezi is derived from the Latin meaning, native of the river, and refers to its capture in the Zambezi River and its tributaries.

Figures

FIGURE 22. Caridina amnicolizambezi sp. nov., RMNH D 24469, ♂: a) Entire. NHM. 2007.735–744, ♀: b) Anterior region of cephalothorax. RMNH D 18639, ♀: c) Anterior region of cephalothorax. RMNH D 24469, ♀ ovig.: d) Anterior region of cephalothorax. ♂: e) Antennular peduncle.

FIGURE 23. Caridina amnicolizambezi sp. nov., RMNH D 24469, ♂: 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. ♀ ovig.: i) First pleopod; j) Eggs. ♂: k) Second pleopod l) Appendix masculina; m) NHM 2007.735–744, ♂: Appendix masculina; n) Appendix masculina; o) Telson; p) Posterior margin of telson; q) Uropod; r) Uropod diaeresis spinules; s) Preanal carina.