Three genera removed from the synonymy of Pinnotheres Bosc, 1802 (Brachyura: Pinnotheridae)

— Three genera, Arcotheres Burger, 1895, Holothuriophilus Nauck, 1880, and Zaops Rathbun, 1900, are removed from the synonymy of Pinnotheres Bosc, 1802. Arcotheres contains only its type species from the IndoWest Pacific, A. palaensis (Burger, 1895). Holothuriophilus is represented by two species from the eastern Pacific, its type species H. trapeziformis Nauck, 1880 and H. pacificus (Poeppig, 1836), a senior synonym of if. silvestrii (Nobili, 1901), a species previously assigned to Pinnaxodes Heller, 1865. Zaops contains a western Atlantic species, Z. ostreum (Say, 1817), the American oyster pea crab; Z. ostreum is an adult and a senior synonym of the type species of Zaops, Pinnotheres depressum Say, 1817. Ongoing studies on some Atlantic species of Pinnotheres prompted me to review the status of its synonyms. As a result of this review, I believe that three genera synonymized with Pinnotheres Bosc, 1802 by Rathbun (1918), Schmitt et al. (1973), and Manning & Holthuis (1981), e.g., Arcotheres Burger, 1895, Holothuriophilus Nauck, 1880, and Zaops Rathbun, 1990, should be recognized as separate genera. Five other pinnotherid genera have been recognized since the summary of pinnotherid taxa was published by Schmitt et al. (1973), as follows: Indopinnixa Manning & Morton, 1987 [type species Indopinnixa sipunculana Manning & Morton, 1987] is a member of the Pinnothereliinae and is not considered further here; all of the other newly recognized genera listed here are members of the subfamily Pinnotherinae. Calyptraeotheres Campos, 1990 [type species Fabia granti Glassell, 1933] differs from Pinnotheres in having a two-segmented mandibular palp. Clypeasterophilus Campos & Griffith, 1990 [type species Dissodactylus rugatus Bouvier, 1917] resembles Dissodactylus Smith, 1870 and differs from Pinnotheres in having the dactyli of the walking legs bifid as well as in having the three segments of the mandibular palp placed end-to-end. Limotheres Holthuis, 1975 [type species Limotheres nasutusHolthuis, 1975] also differs from Pinnotheres in having the segments of the third maxilliped placed endto-end; it further differs in having a projecting, triangular rostrum and three longitudinal postfrontal grooves on the carapace. Tumidotheres Campos, 1989a [type species Pinnotheres margarita Smith, 1869; the genus also includes T. maculatus (Say, 1818)] differs from Pinnotheres in having (a) the dactyli of the walking legs dissimilar and unequal, that of the fifth leg much the longest, and (b) a spatulate dactylus on the palp of the third maxilliped, inserted near midlength of the propodus and not extending beyond the propodus. As pointed out by Campos (1989a:693) the dactylus of the third maxilliped in the type species of Pinnotheres, the European P. pisum (Linnaeus, 1767), is styliform and inserted basally on 524 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON the ventral margin of the propodus; the dactyli of the walking legs in P. pisum are similar and subequal. One genus previously considered to be a pinnotherid has been removed from the family. Mortensenella Rathbun, 1909 [type species Mortensenella forceps Rathbun, 1909] was transferred from the Pinnotheridae to the subfamily Camptandriinae of the Ocypodidae by Harminto & Ng (1991). The genus Orthotheres Sakai, 1969 [type species Orthotheres turboe Sakai, 1969], in which the segments of the palp of the third maxilliped are placed end-to-end, was reviewed by Campos (1989b); it contains some species previously assigned to Fabia and Pinnotheres. Judging from the accounts in Davidson (1968) of Cryptophrys concharum Rathbun, 1893, the type species of Cryptophrys Rathbun, 1893, and of Fabia subquadrata Dana, 1851, the type species of Fabia Dana, 1851, I believe that there may be grounds to consider these two genera as distinct, an action that is beyond the scope of this paper. Cryptophrys and Fabia are now regarded as synonyms (Schmitt et al. 1973:22). The diagnoses given below will distinguish each genus from Pinnotheres s.s. In the diagnoses, pereopods are indicated by their abbreviations, e.g., PI to P5 (PI is the cheliped, P5 the last leg or the fourth walking leg). In the legends, measurements are given as carapace length x carapace width, in millimeters. USNM is an acronym for the National Museum of Natural History, Smithsonian Institution, Washington. Arcotheres Burger, 1895 Fig. 1 A rcotheres Burger, 1895:361. Type species. —Pinnotheres palaensis Burger, 1895, by subsequent designation by Rathbun (1918:62). Gender masculine. Diagnosis. —Carapace subhexagonal. Third maxilliped with ischium and merus indistinguishably fused; exopod with flagellum; palp 3-segmented; propodus much longer than carpus; spatulate dactylus inserted proximally on ventral margin of propodus, not extending to apex of propodus. Dactyli of walking legs dissimilar, those of the third (P4) and fourth (P5) walking legs longer than and different from dactyli of first (P2) and second (P3) walking legs in both sexes. Abdomen of 7 segments in each sex. Remarks. —Arcotheres differs from Pinnotheres in having the dactyli of the last two walking legs longer than and different from the dactyli of the first two, and in having a spatulate rather than styliform dactylus on the third maxilliped. Known only from the type species from the Indo-West Pacific. In pelecypods. Holothuriophilus Nauck, 1880 Figs. 2-3 Holothuriophilus Nauck, 1880:66. Name no. 319 on Official List of Generic Names in Zoology. Type species. —Holothuriophilus trapezifor mis Nauck, 1880, by original designation and monotypy. Gender masculine. Diagnosis. —Carapace broader than long, subrectangular. Third maxilliped with ischium and merus indistinguishably fused; exopod with flagellum; palp 3-segmented; propodus shorter than carpus, conical; spatulate dactylus articulated basally on propodus, extending beyond end of propodus. Dactyli of walking legs similar and subequal, short. Abdomen of 7 segments in both sexes. Remarks. —-I consider Holothuriophilus to be a valid genus distinct from Pinnaxodes. It differs (a) in carapace shape, with the greatest width of the carapace anterior to the midlength in Holothuriophilus, posterior to the midlength in Pinnaxodes; (b) in the proportions of the walking legs which are short and stout, with very short dactyli VOLUME 106, NUMBER 3 525 Fig. 1. Arcotheres palaensis Burger, spent female, 7.8 x 11.1 mm, Philippines, USNM 256948. a, Dorsal view (walking legs of left side omitted; extent of abdomen indicated on both sides); b, Third maxilliped. in Holothuriophilus, slender and elongate in Pinnaxodes whereas these segments are with long dactyli in Pinnaxodes; and (c) in indistinguishably fused in Holothuriophilus. the structure of the third maxilliped, which Members of Pinnaxodes inhabit echinoids, has a suture between the ischium and merus whereas species of Holothuriophilus inhabit