Evidence of co-specificity between Tetranychus evansi and Tetranychus takafujii (Acari: Prostigmata, Tetranychidae): comments on taxonomic and agricultural aspects

ABSTRACT

Using a combination of the cytochrome oxidase subunit I gene (COI) and internal transcribed spacer (ITS) sequence information, cross-breeding, and morphological criteria, the taxonomic status of Tetranychus takafujii was reassessed. Described from Japan and very close to Tetranychus evansi, only the male empodium II separated the two species. Six T. evansi samples collected in Brazil, France, Kenya, Spain (including the Canary Islands), Taiwan, and two samples from Japan previously species-identified as T. takafujii, were examined. DNA sequences consistently divide the samples into two groups: group I held the mites from Brazil and France and group II contained the remaining samples of T. evansi together with the two mites collected in Japan. Likewise, cross-breeding experiments detected the same two groups that were reproductively partially incompatible. However, the Japanese samples were completely compatible with the rest of the group II T. evansi samples. The empodium II shape failed to distinguish consistently between the T. evansi and T. takafujii samples, but rather highlighted its variability, questioning its utility for separating these taxa. Congruent results support the co-specificity of the two taxa. It is concluded that T. takafuji is a junior synonym of T. evansi.

Key words:

• Acari
• systematics
• Tetranychidae, new synonym
• reproductive compatibility
• genetic distance
• morphology

ACKNOWLEDGEMENTS

We are very grateful to Pr. Carlos H. W. Flechtmann for suggesting these investigations. We are also grateful to K. Ohashi and Y. Kitashima (Japan), A. Pallini (Brazil), M. Knapp (Kenya), E. Hernandez Suarez (Spain), and C.-C. Ho (Taiwan) for kindly collecting mites and to P. Auger (France) for his advice and help in the morphological study. This work was supported in part by Grant-in-Aid for Scientific Research (B) (no. 19380032) from Japan Society for the Promotion of Science and by the Project for Agricultural Technology in the Ministry of Agriculture, Forestry, and Fisheries of Japan (no. 18057).