抄録
A group of small-sized species of the genus Cybaeus in western Japan are reviewed and listed under the name Cybaeus hiroshimaensis-group on the basis of genital morphology, retreat type and geographic distribution. The species group contains eleven species, four of which are described as new:C. okumae, C. sasayamaensis, C. nagaiae and C. nagusa. New records of the other seven species are provided:C. hiroshimaensis Ihara 1993, C. gonokawa Ihara 1993, C. tsurusakii Ihara 1993, C. nojimai Ihara 1993, C. okayamaensis Ihara 1993, C. taraensis Irie & Ono 2001 and C. biwaensis Kobayashi 2006. The hiroshimaensis-group is distributed over western Japan, corresponding to the western part of Honshu and northern Kyushu. Distributional ranges of species in the group are parapatric one another, though sometimes they partially overlap. They show remarkable diversity in the genital morphology. This group is also characterized by having the silken tube-like retreat with three terminal openings, instead of two in most other Japanese species of Cybaeus. In addition, Dolichocybaeus Kishida in Komatsu 1968 and Heterocybaeus Komatsu 1968 are newly synonymized with Cybaeus.
