Taxonomic re-examination of Cambaroides (Decapoda: Cambaridae) with a re-description of C. schrenckii from Sakhalin Island Russia and phylogenetic discussion of the Asian cambarids based on morphological characteristics

Abstract

Within the freshwater crayfish genus Cambaroides, there has been taxonomic uncertainly as to the population from Sakhalin Island, Russia, represent Cambaroides schrenckii (Kessler, 1874) or whether it warrants full recognition as C. sachalinensis Birstein and Winogradov, 1934. Detailed morphological examination of specimens from Sakhalin, combined with molecular analysis of the mitochondrial 16S rRNA and COI genes, has shown that they can be regarded as C. schrenckii. We also provide detailed information on the geographic distribution, life history, and habitat of this little known species. Morphology of the epistome, merus of the third maxilliped, and the male second pleopod has phylogenetic importance for freshwater crayfishes in the Northern Hemispere (Astacidae and Cambaridae in Asia and North America). These morphological features are described and illustrated in detail for four species of Cambaroides (Asian Cambaridae), and compared with all representative genera in Astacidae and American Cambaridae. Members of Cambaroides share the same features, and the male second pleopod of Cambaroides has a unique character within Astacidea. This indicates the Asian Cambaridae are monophyletic, and separate from the American cambarid clade, which is consistent with previous molecular data.