It is widely believed that diversity of soil animals are poorer in the tropical zone than in the temperate zone. Is this right? Then, I compared Asian oribatid faunae of the following localities: a tropical lowland rain forest in Pasoh Forest Reserve (Peninsular Malaysia), a subtropical forest in Yunnan Province (China), warm temperate forest in Chiba, a cool temperate forest in Sapporo (Japan), and in a taiga in arctic zone in Siberia (Russia). Samplings in a primary forest and in a 40-year secondary forest, which were 2 ha each and adjacent to each other, showed about 100 oribatid species there. Total species number was estimated at 135 to 150 with Jackknife method. This shows that the species diversity of oribatids are rich in tropics as compared with that in the temperate Japan. Oribatid species richness was even lower in Siberia (Yakutsk) than in Japan. These indicate that oribatid diversity in tropics is higher than in other areas of higher latitudes. Analyses based on Motomura's geometric series rule showed that the inclination became steeper with latitude, also suggesting that a high species diversity in the tropics. Although the number of families did not change greatly with latitude, a DCA analysis showed that composition of families was related with latitude. It was shown that a low latitude area has many winged oribatid mites, such as Haplozetidae, Protoribatidae, and Galumnidae, with many primitive groups in a high latitude area, such as Brachychthoniidae and Hypochthoniidae.

• Kenji Fukuyama(Forestry and Forest Products Research Institute, Japan)