Cybaeus hatsushibai n. sp. (Araneae: Cybaeidae) from Mt. Odaigahara, Honshu, Japan, with notes on geographic distribution and body size of its closely related species.

Abstract

A new medium-sized species of the genus Cybaeus (Araneae: Cybaeidae) from Mt. Odaigahara, Honshu, Japan, is described under the name C. hatsushibai. The new species shows close similarities to C. aquilonalis inhabiting central to northern Honshu and the southwestern part of Hokkaido and C. aokii of central to eastern Hokkaido in external and genital morphology and they are allopatric in their distributions. Thus, they can be recognized as members of a single superspecies. It was found that in C. aquilonalis, the body size tends to be larger in populations in the northernmost Honshu and Hokkaido than those in the central Honshu. On the other hand, C. aokii, which seems to be allopatrically or parapatrically found in Hokkaido to the distributional range of C. aquilonalis, was much smaller than the latter.