| Abstract |
1. The Chrysomelid fauna of the Ryukyu Archipelago and the island of Yakushima is analysed by some quantitative methods. 2. Indices used for the comparison of faunas are the following three indices. i...) Nomura-Simpson’s Coefficient (= Nomura’s Standard Common Ratio, 1939 & 1940, = Simpson’s Coefficient, 1943). ii) Harnomity Index of Subfamilies (CA formula). iii) Harnomity Index of Genera (C, formula). 3. Islands treated in this paper are classified into three fauna1 groups, according to their fauna1 similarities. i) Yakushima. ii) Amami-Oshima and Okinawa Is. iii) Ishigaki and Iriomote Is. 4. The fauna of Tokara Is. is characteristic. According to the number of common species (Nomura-Simpson’s Coefficient), Tokara Is. is related to Amami-Oshima and Okinawa Is. By contrast, the fauna of Tokara Is. is different from the other islands of the archipelago, in accordance with relative representation of subfamilies and genera, and represents a characteristic disharmonic fauna in having dominant Alticids and inferior Galerucids. 5. Though the fauna of Tokara Is. is disharmonic, this should be considered as Subordinate Fauna of Amami-Oshima, in having high persentage of common species with Amami-Oshima. 6. Origin of the disharmonic fauna of Tokara Is. is resulted by sea-invasions of the Ryukyu and Kunigami Periods of Pleistocene. 7. After the regression of ocean, the immigrants to Tokara Is. probably invased from Amami-Oshima and its southern islands, because of the high figures of the Nomura-Simpson’s Coefficient with Amami-Oshima and its southern islands.show more
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