On some hydroids (Cnidaria, Hydrozoa) from the Okinawa Islands, Japan

This paper gives a systematic account of 32 hydroid species identified in a small collection originating from the Okinawa Islands. While most species are well-known from Japanese waters, three new species and five new records for Japan were found. Some not well known species are redescribed. Taxonomically important features of nearly all species are depicted. The new species are: Schizotricha longinema new spec., Cladocarpus unilateralis new spec., and Macrorynchia crestata new spec. Zygophylax pacifica Stechow, 1920 is recognised as a new synonym of Zygophylax cyathifera (Allman, 1888). New records for Japanese waters are: Lytocarpia delicatula, Macrorhynchia fulva, Caminothujaria molukkana, Zygophylax rufa, Thyroscyphus fruticosus. The presence of Zygophylax cervicornis and Aglaophenia cupressina in Japanese waters are confirmed by new, fertile material.