Systematics of the Freshwater Crayfish Genus Cherax Erichson (Decapoda: Parastacidae) in Northern and Eastern Australia: Electrophoretic and Morphological Variation

Abstract

A study of electrophoretic variation amongst 15 putative species of Cherax from northern and eastern Australia supported the recognition of only eight species. Analysis of morphological variation within these crayfish was largely consistent with the taxa identified electrophoretically, although variation in taxonomic characteristics was found to be far more extensive than was previously realised. Of the species identified electrophoretically, only C. dispar Riek and C. rhynchotus Riek are entirely consistent with the most recent taxonomic review of Cherax. The delineation of C. depressus Riek and C. wasselli Riek, although only partially consistent with the accepted geographic distributions of these species, is otherwise similar to the most recent taxonomic treatment. The major taxonomic changes supported by this study involve the delineation of C. cairnsensis Riek, C. cuspidatus Riek, C. destructor Clark and C. quadricarinatus (von Martens). Cherax cairnsensis, which could not be distinguished from the putative C. gladstonensis Riek and, in paa, C. wasselli and C. depressus, is an electrophoretically variable species with an extensive distribution along most of the east coast of Queensland from just north of Calms to just north of Brisbane. The species C. cuspidatus and C. neopunctatus Riek could not be clearly separated from one another and so support a more broadly defined C. cuspidatus. The four species that make up the 'C. destructor' complex (C. albidus Clark, C. davisi Clark, C. destructor Clark and C. esculus Riek) and C. rotundus Clark appear to be part of a single, morphologically variable, species, C. destructor. The redefinition of the northern Australian species C. quadricarinatus to include C. bicarinatus (Gray) from the north-west and C. albertisii (Nobili) from New Guinea is also supported on the basis of both electrophoretic and morphological data. Two species, C. punctatus and C. robustus Riek are more tentatively recognised solely on the basis of morphological evidence.