Caridina malawensis, 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 : 69-72

Caridina malawensis sp. nov.

( Figs. 38 , 39 )

Material examined. Holotype: ♀ ovig. Malawi rocky shore of Lake Malawi, 20.9.– 20.11.1974, coll. P. Lamarque and C. Gosset, pres. Y. Therezien, RMNH D 30477 .

Description. Total length: 17 mm. Carapace length: 2.95 mm.

Rostrum ( Fig. 38a, b ): equal to antennular peduncle. 2.72 mm in length. 0.92 × carapace. 19 teeth on dorsal margin leaving 0.29 of length unarmed only interrupted by single tooth. 2 post-orbital teeth. 9 teeth on ventral margin leaving short unarmed distal end. Tip bifid. Formula (2) 19+1/9.

Antennular peduncle ( Fig. 38e ): 0.8 × carapace. Stylocerite 0.6 × length of basal segment. Anterolateral teeth of basal segment 0.36 × second segment. 9 segments bearing aesthetascs.

Mandible ( Fig. 38c, d ): asymmetrical, with long thin filament attached to the right mandible. (It is not clear whether filament on left mandible was lost).

First pereiopod ( Fig. 39a ): dactylus 1.6 × palm of propodus. Chela 2.2 × long as broad. Carpus 2–2.15 × long as broad with deep excavation.

Second pereiopod ( Fig. 39b ): dactylus 1.33 × long as palm of propodus. Chela 3 × long as broad. Carpus 4.6 × long as broad.

Third pereiopod ( Fig. 39c, d ): dactylus 2.6 × long as broad and with 8 spines (including terminal spines). Propodus 5.4 × long as dactylus and 12.5 × long as broad, with 9 spines along posterior margin. Carpus 0.5 × long as propodus, with minute spines on inner margin. Merus 2.4 × carpus length. Merus with 1 spine on posterior margin.

Fifth pereiopod ( Fig. 39e, f ): dactylus 2.6 × long as broad with 32 spines in a comb like fashion on inner margin. Propodus 13.3 × long as broad and 4.7 × long as dactylus with 6 spines along posterior margin. Car-

pus 0.46 × propodus length and with minute spines along inner margin. Merus 1.94 × carpus length and with 2 spines along inner margin.

Setobranchs: 1 on all pereiopods.

First female pleopod ( Fig. 39g ): endopod 0.55 × long as exopod.

Eggs ( Fig. 39h ): 55, 0.59 × 0.35 mm in size.

Sixth abdominal somite: 0.72 × long as carapace.

Telson ( Fig. 39i, j ): as long as sixth abdominal somite. Dorsal spines 4 pairs (including subterminal spine). Telson tapering towards triangular medial point. Three pairs of alternately short and long thinly plumose spines on posterior margin.

Uropod ( Fig. 39k, l ): 9 diaeresis spinules.

Preanal carina ( Fig. 39m ): unarmed.

Remarks. The single ovigerous female holotyope of C. malawensis , from Lake Malawi, Mozambique, is unique with many distinguishing characters. Among these, of considerable interest is a long filament from the right mandible ( Fig. 38c, d ) that protrudes out into the anterior region of the cephalothorax. However, it is not clear if a filament was originally also present on the left side, but which is now lost. This particular character requires further analysis being known only from a single specimen. It would be interesting to study the function and significance of the long filament ( Fig. 38a, c, d ), as it may provide clues on the feeding mechanism of the species.

The holotype of C. malawensis is unique in other characters: rostrum equal to the antennular peduncle; 19 teeth arranged on dorsal margin of the rostrum proximally, leaving the distal dorsal margin unarmed, interrupted by a single tooth; on the ventral rostral margin bears 9 teeth arranged up to the bifid tip; the dactylus of the fifth pereiopod has 32 spines; and the posterior margin of the telson is triangular with short spines that are alternatively short and long. The ovigerous holotype carries 55 eggs, of 0.59 × 0.35 mm size.

Etymology. Named malawensis , after Lake Malawi.

Figures

FIGURE 38. Caridina malawensis sp. nov., RMNH D 30477, ♀ ovig.: a) Entire; b) Anterior region of cephalothorax; c) Mandibles; d) Mandible right side enlarged; e) Antennular peduncle.

FIGURE 39. Caridina malawensis sp. nov., RMNH D 30477, ♀ ovig.: 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) Eggs; i) Telson; j) Posterior margin of telson; k) Uropod; l) Uropod diaeresis spinules; m) Preanal carina.