HOMOLIDAE DE HAAN, 1839 AND HOMOLODROMIIDAE ALCOCK, 1900 (CRUSTACEA: DECAPODA: BRACHYURA) FROM THE PACIFIC NORTHWEST OF NORTH AMERICA AND A REASSESSMENT OF THEIR FOSSIL RECORDS

摘要

New material collected from Cretaceous and Tertiary rocks of the Pacific Northwest of North America has prompted a reevaluation of the fossil record of the Homolidae de Haan, 1839 and the Homolodromiidae Alcock, 1900. The fossil records of the homolid genera Homola Leach, 1815; Homolopsis Bell, 1863; and Hoplitocarcinus Beurlen, 1928 are restricted, and Latheticocarcinus Bishop, 1988, which is synonymous with Eohomola Collins and Rasmussen, 1992 and Metahomola Collins and Rasmussen, 1992, is reinstated as a distinctive genus. Thirteen new combinations resulted from reinstatement of Latheticocarcinus: L. adelphinus (Collins and Rasmussen, 1992), L. affinis (Jakobsen and Collins, 1997), L. atlanticus (Roberts, 1962), L. brevis (Collins, Kanie, and Karasawa, 1992), L brightoni (Wright and Collins, 1972), L. centurialis (Bishop, 1992), L. declinata (Collins, Fraaye, and Jagt, 1995), L. dispar (Roberts, 1962), L. pikeae (Bishop and Brannen, 1992), L. punctatus (Rathbun, 1917), L. schlueteri (Beurlen, 1928), L. shapiroi Bishop, 1988, L. spiniga (Jakobsen and Collins, 1997), and L. transiens (Segerberg, 1900). A new species, Latheticocarcinus ludvigseni, is described from Cretaceous rocks of British Columbia. The first fossil occurrence of the extant homolid genus Paromolopsis, P. piersoni new species, is recorded from Miocene rocks of Oregon. Paromola pritchardi Jenkins, 1977 is formally transferred to Dagnaudus Guinot and Richer de Forges (1995) as suggested by Guinot and Richer de Forges (1995). The extinct family Prosopidae von Meyer, 1860 is referred to the Homolodromioidea Alcock, 1900, following previous work. Palehomola gorrelli Rathbun, 1926 is transferred from the Homolidae to the Homolodromiidae, and the new genus Rhinodromia is erected to contain Homolopsis richardsoni Woodward, 1896, from Cretaceous rocks of British Columbia. A new terminology is suggested for describing the rostral area in homolodromiids, in an attempt to alleviate considerable confusion over that issue. The morphologic similarity of fossil and extant members in both the Homolidae and the Homolodromiidae suggest that these two brachyuran families are evolutionarily conservative, much as the lobsters are. In addition, the similar paleobiogeographic and evolutionary patterns seen in the two families suggests that either they are closely related or that brachyuran families exhibited similar evolutionary and dispersal trends early in their history.