We investigated the phylogenetic relationships of Stigmaeopsis spider mites (Acari: Tetranychidae) using sequence variation in the cytochrome oxidase subunit I (COI) region of mitochondria DNA. We sequenced a total of 32 samples including four samples of S. takahashii and ten of S. longus from Yamagata Prefecture. Phylogenetic analyses based on the neighbor-joining and the Bayesian method revealed that Stigmaeopsis consists of five monophyletic groups corresponding to each species. Among them, the monophyletic group of S. longus was further divided into two subgroups; one is the northern group composed of the samples from the Hokkaido and Tohoku districts, and the other is the southern group of the samples from the Tohoku, Hokuriku, Shikoku, and Kyushu districts. This suggests that the current distribution of this species has employed two routes of expansion. It is interesting that the samples of S. longus from Yamagata Prefecture were divided into the two groups. This implies that S. longus had multi-expanded patterns of distribution in this prefectur
