A revision of the genus Parastacoides Clark (Crustacea : Decapoda : Parastacidae)

Abstract

Since the last revision of the genus Parastacoides, greatly extended collections, many from previously inaccessible areas, have become available. Some of the new specimens exhibited characteristics intermediate between pairs of the six recognized species. Some 418 specimens were examined for 27 attributes and a numerical classificatory strategy, MULTCLAS, was used to construct a phenetic classification which was expressed as a phenogram and interpreted with the aid of a diagnostic program, GROUPER. A high degree of morphological similarity and a substantial overlapping of ranges of attributes were common. Three groups, identified only by two qualitative attributes, were defined. Accordingly, only one species, P. tasmanicus (Erichson) is recognized, considered to comprise three subspecies corresponding to the three groups. P. pulcher Riek and P. leptomerus Riek are considered synonyms of the nominate subspecies P. tasmanicus tasmanicus (Erichson). P. inermis Clark and P. insignis Clark are retained as the subspecies P. tasmanicus inermis (Clark) and P. tasmanicus insignis (Clark) respectively. P. sternalis Riek is considered a synonym of P. tasmanicus inermis. Two possible patterns of evolution of the subspecies are briefly considered.