Caridina okiamnis , Jasmine Richard & Paul F. 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, Zootaxa 1995, pp. 1-75: 54-57

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Caridina okiamnis

sp. nov.

Caridina okiamnis  sp. nov.

( Figs. 28 View Figure , 29 View Figure )

Material examined. Holotype: ♀ ovig. Cameroon Okia stream, 10.11.70, coll. R. H. L. Disney, NHMAbout NHM 1974.694. Paratypes: Okia stream, 14.11.68, coll. R. H. L. Disney, NHMAbout NHM 1974.693, 1♀ ovig., 2♀.

Description. Total length: 20–22 mm. Carapace length: 3.7–4 mm.

Rostrum ( Fig. 28a, b, c View Figure ): equal to antennal scale, 3.7–3.9 mm in length. 0.85–0.95 × carapace. 20–22 teeth on dorsal margin leaving 0.28–0.30 of length distally unarmed. 5 post-orbital teeth. 10–11 teeth on ventral margin arranged to tip. Tip pointed. Formula (5) 20–22/10–11.

Antennular peduncle ( Fig. 28d View Figure ): 0.75 × carapace. Stylocerite 0.6–0.9 × length of basal segment. Anterolateral teeth of basal segment 0.42 × second segment. 8–10 segments bearing aesthetascs.

First pereiopod ( Fig. 29a View Figure ): dactylus 1.2–1.3 × palm of propodus. Chela 2.2 × long as broad. Carpus 2–2.15 × long as broad with deep excavation.

Second pereiopod ( Fig. 29b View Figure ): dactylus 1.2–1.25 × long as palm of propodus. Chela 2.75–2.8 × long as broad. Carpus 4–4.25 × long as broad.

Third pereiopod ( Fig. 29c, d View Figure ): dactylus 2.1–2.2 × long as broad. Spines on dactylus varying from 6–8 (including terminal spines). Propodus 6.5–6.8 × long as dactylus and 13.5–14.5 × long as broad with 12–15 spines arranged along posterior margin. Carpus 0.56 × long as propodus, with minute spines on inner margin. Merus 1.9–2 × carpus length. Merus with 2 spines on posterior margin.

Fifth pereiopod ( Fig. 29e, f View Figure ): dactylus 3.4–3.5 × long as broad with 30–50 spines arranged in comb-like fashion on inner margin. Propodus 12–13 × long as broad and 4.1–4.2 × long as dactylus with 15–20 spines arranged along inner margin. Carpus 0.55–0.6 × propodus length and with minute spines along inner margin. Merus 1.4–1.5 × carpus length and with 1 spine along inner margin.

Setobranchs: 2 on all pereiopods.

First female pleopod ( Fig. 29g View Figure ): endopod 0.75 × long as exopod.

Eggs ( Fig. 29h View Figure ): 9–10, 1.05–1.13 × 0.55–0.68 mm in size.

Sixth abdominal somite: 0.57 × long as carapace.

Telson ( Fig. 29i, j View Figure ): 1–1.1 × long as sixth abdominal somite. Dorsal spines 5 pairs (including subterminal spine). Broad with flat posterior margin bearing 1 pair of longer lateral spines and 3 pairs of plumose processes increasing in length towards centre giving triangular appearance.

Uropod ( Fig. 29k, l View Figure ): 14–16 diaeresis spinules.

Preanal carina ( Fig. 29m View Figure ): peg-like and unarmed.

Remarks. Caridina okiamnis  sp. nov. is distinguished by the combination of: straight rostrum having the dorsal distal margin unarmed with a pointed tip; ventral margin of rostrum characteristically arched with 10 or 11 teeth evenly arranged up to the tip; the rostrum has 5 post-orbital teeth; overigerous females with few eggs (10 or 11); the telson is broad with a flat posterior margin possessing comparatively longer lateral spines and short plumose processes arranged on a flat posterior margin giving a triangular appearance; and the uropod diaeresis possesses 14–16 spinules. Unfortunately, the type series does not include males.

Etymology. The name, okiamnis  , is a combination of the name Okia, stream from which the type material was collected, and the Latin, amnis, meaning stream.


University of Nottingham