Abstract: Ectoparasitic gamasid mites associated with small mammals have long been suspected to be the vectors of some zoonoses such as hemorrhagic fever with renal syndrome (HFRS) and rickettsialpox. In this paper, the results of wild investigations of the gamasid mites associated with small mammals in 28 counties of Yunnan, China is reported. The characteristics of community and describe the spatial distribution of gamasid mites along an environmental gradient are analyzed by using species richness, Shannon diversity index. In addition, the similarity of 18 mite infracommunities was compared by using hierarchical clustering analysis (SPSS 16.0). A total of 14 544 individuals of small mammals belonging to five orders (Rodentia, Insectivora, Scandentia, Lagomorpha and Carnivora), 10 families, 35 genera and 67 species were trapped, from which 80 791 individuals of gamasid mites representing 10 families, 33 genera and 112 species were collected. The results indicated that the dominant host species were Rattus tanezumi, Apodemus chevrieri, and Eothenomys miletus, while dominant gamasid mite species were Laelaps nuttalli, L. echidninus and L. guizhouensis. The mite infracommunities associated with A. chevrieri, N. confucianus and R. tanezumi exhibited the highest species richness, while mite infracommunities on Suncus murinus, Apodemus chevrieri and Crocidura attenuata presented the highest diversity. The results of cluster analysis showed that the similarity of most mite communities in accordance with the taxonomic relationship and the habitat of their corresponding small mammal hosts. The mite communities are clustered into the same group when their hosts are similar in zoological taxonomy and habitat selection. The horizontal patterns of gamasid mite species richness along a latitudinal gradient showed two peaks, the highest richness was recorded at the latitude 25°N to 26°N, while the vertical patterns presented a single-peak curve along the elevation gradient, peaking at the elevation of 2 000 m to 2 500 m. The diversity spatial distribution patterns of gamasid mites and their small mammal hosts showed the similar trends of single-peak curves which gradually increased and then decreased with increasing of latitude and elevation, peaking at the latitude 26°N to 27°N and the elevation of 2 000 m to 2 500 m. The results suggest that the community structure of gamasid mites in Yunnan Province has high species richness and diversity. The spatial distribution patterns of gamasid mites in Yunnan Province may be the results of the edge effect between the Oriental and Palaearctic realms.

Key words: Gamasid mites, small mammals, community structure, spatial distribution, cluster analysis, Yunnan