Zoogeography in southern Japan as revealed by ground-living arachnids

Abstract

In the past, primarily birds and butterflies, but also amphibians, reptiles and mammals, have been used for Zoogeographic studies in southern Japan. Meanwhile, taxonomic studies have also been carried out on arthropod groups living in and on the soil. Since it is quite unlikely that these ground-living organisms have crossed the sea, either actively or passively, they are ideal for Zoogeographie studies. The present investigations are based on four groups of ground-living arachnids: whipscorpions and spiders (Hexathelidae, Ctenizidae, Mesothelae). A close zoogeographical connection was found between the Yaeyama, Islands and nearby Taiwan. The central and northern parts of the Ryukyu Islands are faunistically closest to Kyushu. No distinct border between an Oriental and a Palaearctic fauna can be detected. Instead, only climatic and other ecological factors appear to be responsible for distributional boundaries of various organisms observed in different regions of southern Japan. Similarities to the fauna of continental China can be explained by land connections between the Ryukyus and the continent during the Pleistocene.