Taxonomic re‐examination of the two camptandriid crab species Deiratonotus japonicus (Sakai, 1934) and D. tondensis Sakai, 1983, and genetic differentiation among their local populations
Morphological and genetic characteristics were investigated for two allied brachyuran species, Deiratonotus japonicus (Sakai, 1934) and D. tondensis Sakai, 1983 (family Camptandriidae), occurring in upstream brackish water areas of western Japan. Our observations on over 400 crab specimens from 13 localities, including the types, revealed that there were many specimens that could not be identified morphologically as either species by their diagnostic characters indicated in original descriptions. We grouped specimens into three morphological types of “ D. japonicus ”, “ D. tondensis ” and species‐unknown. Specimens of three morphological types were often found even in the same localities. Moreover, there was no correspondence between the morphological types and mitochondrial DNA haplotypes (COI, 540 bp), which was revealed by phylogenetic analyses using maximum likelihood methods and a statistical‐parsimony haplotype network constructed with the TCS computer program. In addition, genetic distance between “ D. japonicus ” type and “ D. tondensis ” type (0–1.7%) were in the intraspecific range of Crustacea. Thus, D. japonicus and D. tondensis ought to be treated as the same species and the latter nominal species as a junior synonym of the former. Significant genetic differentiation was recognized among populations with a positive correlation between geographic and genetic distances, suggesting isolation by distance. In consequence, a redescription of the newly defined Deiratonotus japonicus is presented, taking into account the newly recognized morphological variability in this species.
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Document Type: Research Article
Affiliations: Department of Biological Science, Faculty of Science, Nara Women's University, Nara, Japan
Publication date: 01 January 2005