Geographic differentiation of the miyosii-group of Cybaeus (Araneae: Cybaeidae) in western Japan, with descriptions of two new species

Abstract

Four known species, Cybaeus miyosii Yaginuma 1941, C. okafujii Yaginuma 1963, C. kumaensis Irie & Ono 2001 and C. hibaensis Ihara 1994, and two new species, C. kunisakiensis and C. tsurugi are described as the miyosii-group in the genus Cybaeus (Cybaeidae). These six species are small to medium in size and pale in color compared to other species of each of the local species assemblages. The miyosii-group is distributed over western Japan, corresponding to the Chugoku district (western Honshu), Shikoku and Kyushu. Each species of the group occupies a fragment within an overall geographic range of the group. Since these six species show close similarities in external morphology and they are parapatric in their distribution, they can be recognized as a single superspecies.