Abstract

DAWSON, Jessica  and  GRIFFITHS, Charles L.. Revision of the crown crabs, genus Hymenosoma (Crustacea: Hymenosomatidae), of South Africa. Afr. nat. history (Online) [online]. 2012, vol.8, pp.16-29. ISSN 2305-7963.

Recent genetic studies have shown that the South African crown crab, Hymenosoma orbiculare, in fact represents five distinct species, three of which are new to science and one of which needs to be resurrected. Three of these species occur in the southwestern Cape, the remaining two being found in estuaries on the South East and East coasts of South Africa. Based on genetic evidence and morphological analyses, H. geometricum Stimpson, 1858 is no longer considered a junior synonym of H. orbiculare, and is resurrected as a full species. A deeper-water species from False Bay, H. trilobatum sp. nov. as well as two East coast species, H. longicrure sp. nov. and H. projectum sp. nov., are described. The true H. orbiculare ranges from Walvis Bay in Namibia to the Gqunube Estuary near East London. H. geometricum and H. trilobatum sp. nov. are both found in deeper water and are currently known only from False Bay. H. longicrure sp. nov. is found from the Qolora Estuary to the Mngazi Estuary in the Eastern Cape and H. projectum sp. nov. along the east coast from the Mzimvubu Estuary to Lake Sibaya and Kosi Bay. The size and shape of the rostrum and ornamentation of the carapace are the main features distinguishing species. H. orbiculare has a smooth, simple rostrum and only two pairs of plain teeth on the carapace; H. geometricum has a very complex, long, trilobate rostrum and three pairs of complex, granulate teeth on the carapace; H. trilobatum sp. nov. has a less complex, extended, trilobate rostrum with smooth margins and granulate surface, with only two pairs of teeth on the carapace; H. longicrure sp. nov. and H. projectum sp. nov. both have a simple rostrum, little ornamentation on the carapace and unusual abdominal projections.

Keywords : Hymenosoma; new species; crown crab; South Africa; taxonomy.

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