Cryptocnemus grandidieri A. Milne-Edwards, 1865

Galil, Bella S. & Innocenti, Gianna, 2019, Rare and new East African leucosiid crabs, Zootaxa 4555 (1), pp. 139-145 : 140

Cryptocnemus grandidieri A. Milne-Edwards, 1865

( Fig. 1 A–C)

Cryptocnemus Grandidierii A. Milne-Edwards 1865: 155 , pl. 6, fig. 4; 1868: 72 (list).

Cryptocnemus grandidieri, Guinot 1967: 250 (list).

Material examined. Holotype, male (5.5 x 8.1), MNHN B-3987, Zanzibar, coll. A. Grandidier, 1864, preserved dry.

Other material. 1 female (7.8 x 12.4), MZUF-4447, Kenya, Mombasa, reef, colls S. Cianfanelli, E. Talenti, G. Innocenti, Sept. 2000 .

Description. Carapace transversely suboval in outline, 1.6 times wide as long, with strongly expanded branchial regions concealing ambulatory legs; prominent tribranched ridge; margins lamellate, upcurved, closely and minutely scalloped ( Fig. 1A ). Front narrow, very slightly produced, upturned, triangular. Anterior margin distinctly sinuous, minutely and irregularly scalloped; lateral and posterior margins continuous, rounded; posterior margin bearing two flattened submedian lobes. Postfrontal median ridge prominent, finely granulate, meeting at raised, prominently granulate gastrocardiac region with granulate ridges extending to posterolateral angles. The rest of the upper surface of carapace is smooth to the naked eye. Hepatic regions concave, sloping from postfrontal median ridge. Antennule folded into slightly diagonal fossa. Ocular peduncle short. Orbital hiatus on infraorbital margin closed by basal segment of antenna. Suborbital region granulate. Anterolateral margin of buccal region raised, granulate, running parallel to anterolateral margin distally. Third maxilliped with merus nearly as long as ischium along mesial margin, granulate; exopod slightly arcuate along lateral margin, granulate. Surfaces of pterygostomial, sub-hepatic and sub-branchial regions smooth, sparsely punctate. Cheliped slender. Merus trigonal, posterior, anterior margins finely scalloped. Carpus globular, upper margin carinate. Palm laterally compressed, elongate; upper and lower margins carinate. Fingers short, tips crossing when closed, upper margin of dactyl scalloped. Ambulatory legs smooth, laterally compressed, carinate, lamellate, gradually decreasing in length from first to fourth, hidden in dorsal view by extended branchial regions of carapace when retracted. Pleon strongly convex, dome-like, obsoletely granulate, telson laciniate ( Fig. 1B ). Sternopleonal cavity with prominent, granulate rim, deep, completely covered by pleon; sutures separating thoracic sternites medially interrupted, median part of cavity smooth; vulvae on anterior edge of sternite 6, pushing into sternite 5, opening circular, with round operculum, inner margin raised.

Colour (in life). Bone white, like bleached coral (fide G. Innocenti).

Remarks. Alfred Grandidier, a French explorer and naturalist, visited Zanzibar in 1864 collecting “… quelques espèces très curieuses” ( Grandidier 1868:5). Alphonse Milne Edwards (1868: 70), who described C. grandidieri from that material, remarked that the collection comprised a great number of samples the study of which seemed to him most interesting, because many belonged to new species, and some constitute forms distinct from all those known until then and impossible to place in any known genus. The species has not been reported since.

The present specimen differs slightly from the illustrations accompanying A. Milne-Edwards’ description (1865: pl. 6, fig. 4) e.g., the front is triangular rather than horizontal and the anterior margins are sinuous. However, these disparities may be due to the angle of viewing the specimen ( Fig. 1C ).

Geographical distribution. Known only from the type locality, Zanzibar, Tanzania ( A. Milne-Edwards 1865), and now also from Mombasa, Kenya.

Figures

FIGURE 1. Cryptocnemus grandidieri A. Milne-Edwards, 1865; A, B, female, 7.8 x 12.4 mm, (MZUF-4447) from Mombasa, Kenya; C, holotype, male, 5.5 x 8.1 mm, (MNHN B. 3987) from Zanzibar, Tanzania; A, C carapace, dorsal view; B, carapace, ventral view.