Re-examination of species in the Pacifastacus subgenus Hobbsastacus (Decapoda: Astacidae)

The genus Pacifastacus contains two subgenera, Pacifastacus and Hobbsastacus, the latter of which contains the following four extant species, Pacifastacus (H.) gambelii (Girard, 1852), P. (H.) nigrescens (Stimpson, 1857), Pacifastacus (H.) fortis (Faxon, 1914), and P. (H.) connectens (Faxon, 1914), and one fossil representative, P. (H.) chenoderma. Pacifastacus (H.) fortis and P. (H.) connectens were re-examined on the basis of the type specimens and additional materials collected from California (P. fortis) and Idaho, as well as Oregon (P. (H.) connectens), USA. Lectotypes of P. connectens and P. fortis were designated, and subsequently the two species were re-described and illustrated with their full synonymies. Brief diagnoses of P. (H.) gambelii (Girard, 1852) and P. (H.) nigrescens are also provided. Detailed distributions of these species are presented based on data from voucher specimens. Following new findings in this study, the generic diagnoses of the genus Pacifastacus and the subgenus Hobbsastacus were updated.