Caridina gaesumi , 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: 57-60

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Caridina gaesumi

sp. nov.

Caridina gaesumi  sp. nov.

( Figs. 30 View Figure , 31 View Figure )

Material examined. Holotype: ♀ ovig. Nigeria Osse River (Ovia River) near Gilli Gilli, Midwest State, 6°9.5'N 5°21'E, 16.5.1975, coll. & pres. C. B. Powell, RMNHAbout RMNH D 30480. Paratypes: Lagune of Ogba River, S of Ogba, Midwest State, 6°17'N 5°35'E, 16 and 22.5.1975, coll. & pres. C. B. Powell, RMNHAbout RMNH D 30479, 7♀ ovig., 3♀; Osse River (Ovia River) near Gilli Gilli, Midwest State; 6°9.5'N 5°21'E, 16.5.1975, coll. & pres. C. B. Powell, RMNHAbout RMNH D 30480, 5♀ ovig., 3♀. Republic of Zambia Irrigation ditch, Nakambala Sugar estate, Mazabula, 29.6.1981, pres. J. Pollock, NHMAbout NHM 1982.139, 1♂.

Description. Total length: 14–23 mm. Carapace length: 2.9–3.2 mm.

Rostrum ( Fig. 30a, b, c View Figure ): reaching apex of antennal scale. 2.4–2.8 mm in length. 0.8–0.9 × carapace. 10–20 teeth on dorsal margin leaving 0.3–0.4 of length distally unarmed sometimes interrupted by 1–2 teeth. 1–3 post-orbital teeth. 3–9 teeth on ventral margin arranged to tip. Tip pointed or bifid. Formula (1–3) 10–20/ 3–9.

Antennular peduncle ( Fig. 30d View Figure ): 0.65–0.75 × carapace. Stylocerite 0.7–0.9 × length of basal segment. Anterolateral teeth of basal segment 0.25–0.4 × second segment. 5–9 segments bearing aesthetascs.

First pereiopod ( Fig. 31a View Figure ): dactylus 1.3–1.4 × palm of propodus. Chela 2.4–2.5 × long as broad. Carpus 2.3–2.5 × long as broad with anterior excavation.

Second pereiopod ( Fig. 31b View Figure ): dactylus 1.1–1.2 × long as palm of propodus. Chela 3.1–3.3 × long as broad. Carpus 6.5–7.1 × long as broad.

Third pereiopod ( Fig. 31c, d View Figure ): dactylus 2.5–3 × long as broad.4–9 spines on dactylus (including terminal spines). Propodus 5–5.2 × long as dactylus and 13.5–15 × long as broad with 7–10 spines along posterior margin. Carpus 0.5–0.6 × long as propodus, with minute spines on inner margin. Merus 1.5–1.7 × carpus length. Merus with 4 spines on posterior margin.

Fifth pereiopod ( Fig. 31e, f View Figure ): dactylus 2.4–2.6 × long as broad with 25–45 spines arranged in comb-like fashion on inner margin. Propodus 13–14 × long as broad and 3.5–4.0 × long as dactylus with 9–12 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 along inner margin.

Setobranchs: 2 on all pereiopods.

First male pleopod ( Fig. 31g, h View Figure ): endopod 0.4 × exopod; appendix interna absent. Short setae present on margin.

First female pleopod ( Fig. 31i View Figure ): endopod 0.5–0.6 × long as exopod.

Eggs ( Fig. 31j View Figure ): 10–15, 0.9–1.1 × 0.5–0.6 mm in size.

Second male pleopod ( Fig. 31k View Figure ): appendix masculina 1.3 × appendix interna. 0.35 × endopod. Several stalked spines along posterior margin.

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

Telson ( Fig. 31m, n, o View Figure ): 1–1.1 × long as sixth abdominal somite. 4–5 pairs of dorsal spines (including sub terminal spines). Broad with pair of longer lateral spines almost reaching 0.6–0.9 of inner plumose process. 1–3 pairs or 3 or 5 stalked plumose processes present at posterior margin.

Uropod ( Fig. 31p View Figure ): 7–10 diaeresis spinules.

Preanal carina ( Fig. 31q View Figure ): Sharp with spine or unarmed.

Remarks. Caridina gaesumi  sp. nov. is distinguished by the following characters: rostrum straight, reaching apex of antennal scale, dorsal teeth 10–20, arranged up to the tip or leaving the 0.3–0.4 of the dorsal distal margin plain, which is interrupted by teeth; 3–9 teeth on the ventral margin of the rostrum arranged from the proximal end up to the tip; tip of the rostrum pointed or bifid; 20–45 spines on the dactylus of the fifth pereiopod; few eggs in ovigerous females (10–15); and longer lateral spines on the posterior margin of the telson.

Caridina gaesumi  is similar to C. togoensis  in the arrangement of teeth on the dorsal margin of the rostrum, either compactly arranged up to the tip or with a short distal unarmed margin, and in bearing plumose processes at the posterior margin of the telson. However, the unarmed dorsal distal margin, when present, could be interrupted by teeth in C. gaesumi  sp. nov. whereas it is plain in C. togoensis  . Also the tip of the rostrum could be either pointed or bifid in C. gaesumi  sp. nov. whereas it is pointed in C. togoensis  . Caridiana gaesumi  sp. nov. differs from C. togoensis  in possessing comparatively longer lateral spines on the posterior margin of the telson.

Etymology. The specific name is derived from g aesum, Latin, meaning a long heavy javelin, referring to the distinguishing character of this species, namely the long lateral spines on the posterior margin of the telson.


National Museum of Natural History, Naturalis


University of Nottingham