Leucisca halimedophila, Galil & Innocenti, 2019

Galil, Bella S. & Innocenti, Gianna, 2019, Rare and new East African leucosiid crabs, Zootaxa 4555 (1), pp. 139-145 : 140-142

Leucisca halimedophila n. sp.

( Figs 2A, B , 4 A–C)

Material examined. Holotype, male (9.2 x 11.8), MZUF-4446, Kenya, Watamu, reef, colls S. Cianfanelli, E. Talenti, G. Innocenti. Sept. 2000 . Paratypes, 1 male (10.4 x 7.8), 1 young female (6.5 x 8.1), MZUF-4930.

Description of holotype. Carapace transversely suboval in outline, about 1.3 times as wide as long, with greatly expanded branchial regions concealing ambulatory legs; dorsal surface smooth to the naked eye, margins lamellate, upcurved, closely and minutely granular, prominent conical protuberance medially ( Fig. 2A ). Front narrow, produced, upturned; margin slightly concave. Anterolateral margin rounded, continuous with posterior margins; posterior margin slightly wider than frontal margin, sinuous, bearing two flattened submedian lobes. Rounded median ridge running from front to conical gastrocardiac protuberance, culminating in cluster of flattened granules. Intestinal region with low protuberance medially. Epibranchial ridge rounded, inconspicuous, running obliquely from gastrocardiac protuberance to posterolateral margin.

Ocular peduncle very short. Antennule folded into oblique fossa. Infraorbital margin with orbital hiatus closed by basal segment of antenna, distally with granulate pit. Anterolateral margin of buccal region raised, granulate, running parallel to anterolateral margin distally, notched on anterior margin. Third maxillipeds with margins of exopod and endopod closely granulate; endopod merus nearly as long as ischium along mesial margin, distally granulate; exopod slightly arcuate. Surfaces of pterygostomial, sub-hepatic and sub-branchial regions smooth, sparsely punctate. Cheliped slender. Merus trigonal, margins prominently granulate. Carpus globular, granulate; upper margin carinate. Palm laterally compressed, elongate, margins carinate, boldly granular; inner surface bearing a curving row of pearliform granules extending to dactylar articulation. Fingers short, bearing rows of granules extending to tips, tips crossing when closed. Ambulatory legs granulate, laterally compressed, similar in shape, gradually decreasing in length from first to fourth, hidden by extended branchial regions of carapace in dorsal view when retracted; meri unicarinate, carpi, propodi bicarinate on upper margins, meri bicarinate, propodi unicarinate on lower margins. Pleon with proximal two somites narrow, yoke-shaped; distal somites fused, bearing large triangular denticle subterminally; telson subtriangular ( Fig. 2B ). G1 ( Fig. 4A,B ) stocky, sinuous, distally setose, tip claw like. G2 short, filiform, tip laciniate ( Fig. 4C ).

Colour (in life). Carapace, legs, bone colored; brown stripe running along median ridge from front to conic gastrocardiac protuberance, 3 brown dots on posterior margin (fide G. Innocenti).

Etymology. The specific epithet, halimedophila , alludes to the carapace shape of the new species, which convincingly resembles a segment of dead coralline algae ( Halimeda spp.). Used as an adjective.

Distribution. Known from specimens collected from the type locality – Watamu, Kenya.

Remarks. Leucisca halimedophila n. sp. resembles L. rubifera (Müller, l887) in the general outline of the carapace and chelipeds, and in possessing triangular denticle subterminally on male abdomen, but the present species is distinguished by a broader carapace, more prominent conic gastrocardiac protuberance, and less prominent intestinal protuberance than L. rubifera (Müller l887: tab. 4, fig. 4, 4a,b; Tirmizi & Kazmi 1979: fig. 3a,b; Naderloo 2017: fig. 14.20). The posterior margin is produced, bearing two flattened submedian lobes, rather than smoothly convex as in L. rubifera . The granulation on margins of the carapace, thoracic sternites, 3rd maxillipeds are much finer than in L. rubifera . Finally, G1 is stocky, sinuous, distally setose, and with a claw-like distal tip, rather than styliform as in L. rubifera ( Tirmizi & Kazmi 1979: fig. 3c; Naderloo 2017: fig. 14.21c).

Figures

FIGURE 2. Leucisca halimedophila n. sp.; holotype, male, 9.2 x 11.8 mm, (MZUF-4446) from Watamu, Kenya; A, carapace, dorsal view; B, carapace, ventral view.

FIGURE 4. A–C, Leucisca halimedophila n. sp.; A-C, holotype, male, 9.2 x 11.8 mm, (MZUF-4446) from Watamu, Kenya; D, Nobiliella margaritata sp. nov.; holotype, male, 7.2 x 8.0 mm, (MZUF-4450) from Massawa, Eritrea. A, D, right first male pleopod, external view; B, same, internal view; C, right second male pleopod, external view. Scale bar: 1 mm.