| Summary: | 碩士 === 國立中興大學 === 生命科學系所 === 100 === The freshwater crabs of the genus Geothelphusa are not easily separated morphologically, and almost are relied on the shape of male gonopod 1 with only small difference within and between species. Previous studies showed that most species can be supported by genetic evidence. However, species within the Geothelphusa olea complex from southwestern Taiwan and the G. tawu complex from southeastern Taiwan can not separated by the mitochondrial COI of 16S rRNA genes. This study attempts to understand the species identification for Taiwanese Geothelphusa by the mitochondrial COI, and nuclear ITS-1 and ITS-2 (internal transcribed spacer 1 and 2). The results show that, according to the COI tree, the Taiwanese Geothelphusa species can be divided into two clades. One is the G. miyazakii complex. Three gene trees support the Taiwanese G. miyazakii, and the Ryukyuan G. marginata and G. fulva as three clades. The other is the remaining Geothelphusa species in Taiwan, which can be divided into the western and eastern clades based on COI tree, although the ITS-1 and ITS-2 trees do not have this tendency. In the COI tree, the G. olea complex is an unsolved clade, but ITS-1 and ITS-2 analyses show G. caesia is monophyletic and support it is a valid species. G. tawu complex forms a clade with higher support in COI tree suggesting it is a single species; although the support is weak in the ITS-1 tree. For the G. eucrinodonta complex, G. eucrinodonta, G. aff. olea from Taoyuan, Hsinchu and Miaoli, and G. yangmingshan form three clades in the COI tree. Although ITS-1 tree does not support the results in COI tree, it shows G. eucrinodonta and G. siasiat form a large clades. In the G. pingtung complex, G. makotao and G. pingtung are two separate clades in COI tree, but both form an unsolved clade in ITS-1 tree. Some inconsistencies between nuclear mitochondrial markers are suggested to be caused by the effect from biparental or maternal inheritance, for ITS or COI genes, respectively. This study supports the ITS gene can help clarify the validity of some Taiwanese Geothelphusa species.
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