Petrolisthes cf. donanensis Osawa, 1997

Werding, Bernd & Hiller, Alexandra, 2007, The Porcellanidae (Crustacea: Decapoda: Anomura) of the Red Sea with description of a new species of Petrolisthes, Zootaxa 1460, pp. 1-24 : 8-10

7. Petrolisthes cf. donanensis Osawa, 1997

( Fig. 7 )

Petrolisthes donanensis Osawa, 1997: 58 , figs. 1A–H, 2A–G.

Material examined. 1 ɗ ( SMNS part of ZIa 3365), Egypt, Red Sea, Koseir, 1883, leg. Klunzinger. Measurements. 3.1 x 2.9 mm.

Description. Carapace with two epibranchial spines and a conspicuous supraorbital spine. Infraorbital angle accentuated, but without spine, no mesobranchial spines; surface of carapace smooth, except for faint striations on the posterior branchial region. Front broad, extending beyond eyes. First movable segment of antennae with a forwardly projected, spine-tipped, lamellar lobe.

Chelipeds slender, merus with two forwardly projected spines on anterior margin, inner distal angle tapered. Carpus with a longitudinal ridge, composed of scale-like granules, anterior margin armed with 4 irregular teeth, distal edge almost right-angled; posterior margin with a row of curved spines, increasing in size distally. Manus with a longitudinal ridge, composed of a row of scales, extending over the dactylus; outer margin armed on proximal half with irregular, massive spines, the distal half irregularly serrated. Outer margin of dactylus armed with a fine serration. Only two walking legs (L2, L3) present, merus with 6 spines on anterior margin, dactylus armed with four movable spines.

Remarks. Among the Indo-West Pacific species of Petrolisthes the combination of two epibranchial spines and absence of mesobranchial spines corresponds to P. donanensis Osawa , P. bispinosus Borradaile , P. decacanthus Ortmann and P. eldredgei Haig & Kropp. This combination of features is also found in P. c o l u m - biensis Werding and P. rosariensis Werding from the western Atlantic and in P. glasselli Haig from the eastern Pacific. All species, except P. donanensis , bear characteristic transverse ridges on carapace and chelipeds. The specimen examined here corresponds to P. donanensis in its general characters, but is distinguished from the two described P. donanensis type-specimens by the formation of the front region, which is less produced and more triangular in P. donanensis . Also, P. donanensis has relatively smaller eyes. Because the only available specimen is very small and incomplete, a reliable identification seems impossible.

Distribution. Osawa (1997) reported P. donanensis from the Ryukyu Islands, Japan.

Figures

FIGURE 7. Petrolisthes c. f. donanensis, male, Egypt, Red Sea, Koseir (SMNS ZIa 3365). (a) Carapace, dorsal view. (b) Left cheliped, dorsal view. (c) Second walking leg, dorsal view. (d) Third walking leg, dorsal view.