PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 116(4):901-919. 2003. On two new genera of pea crabs parasitic in holothurians (Crustacea: Decapoda: Brachyura: Pinnotheridae) from the Indo-West Pacific, with notes on allied genera Peter K. L. Ng and Raymond B. Manning* (PKLN) Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 119260, Republic of Singapore, e-mail:
[email protected] sg; (RBM) Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560-0163 Abstract. — Two new genera of pea crabs of the family Pinnotheridae, Hol-otheres and Buergeres, members of which are parasites of sea cucumbers, are described from the Indo-West Pacific. Species of Holotheres are characterized by having all the dactyli of the walking legs of females short and subequal in length, with the spatuliform dactylus of the third maxilliped inserted very near or at the base of the propodus. Species of Buergeres are characterized by having the last dactyli of the walking legs of females elongate and longer than those of the other legs, with the subspatuliform dactylus of the third maxilliped inserted distinctly before the base of the propodus. Holotheres and Buergeres are compared to other genera whose members are associated with holothurians, Holothuriophilus Nauck, 1880, and Alain Manning, 1998 (obligate parasites); as well as Pinnaxodes Heller, 1865 (facultative parasites). In a synopsis of the Pinnotheridae, Man-ning (1993a: 127, 128) defined the genus Pinnotheres Bosc, 1802, sensu stricto as having a subhexagonal or subcircular cara-pace without any surface ornamentation or sculptures, a third maxilliped which has the ischium and merus completely fused (with-out any trace of a suture) and a three-seg-mented palp in which the dactylus is slen-der, inserted basally on the propodus; the dactyli of the first to fourth walking legs are subequal and similar, short and strongly curved, with the tips simple; and all the seven male abdominal somites are free. Manning (1993a), however, did not treat most of the species of Pinnotheres which live in holothurians, all of which have a third maxilliped in which the dactylus is not slender but spatuliform to subspatuliform. * Deceased 18 January 2000. In addition, the third maxilliped of most of these species has the inner margin usually angular, and the carpus of the third maxil-liped is distinctly shorter than the propodus that is relatively long and slender. In this combination of characters, these species are very different from almost all other taxa now classified in Pinnotheres sensu stricto or any of the other non-holothurian sym-biotic genera recognized or described by Manning (1993a, 1993b) and other work-ers. Manning (1993a: 128) did note briefly in his synopsis, however, that one genus parasitic in holothurians, Holothuriophilus Nauck, 1880, was valid, and subsequently elaborated more on this (Manning 1993b). Currently, 16 species of pinnotherid crabs are known to be parasites of holothu-rians, and of these, 13 occur only in the Indo-West Pacific (see Schmitt et al. 1973, Hamel et al. 1999). The eastern Pacific spe-
Specimen codes extracted from OCR text.
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