Abstract: Seirphidiumdominated desert, widely distributed in northern Xinjiang, bears grazing pressure in both spring and autumn. Due to the dry climate, the decomposition of feces of grazing livestock strongly depends on dung beetles. In this study, we recorded the seasonal variation and species diversity of dung beetles in the Seirphidiumdominated desert grassland. A total of 14797 dung-eating insects were captured, belonging to 19 species and 3 families, in which there were 10 species from Aphodiidae, 8 species from Scarabaeidae, 1 species from Geotrupidae. The species richness gradually increased from April to June. The dominant species was Aphodius sublimbatus. The beetle abundance in spring and autumn grazing season (April to May, September to October) was greater than that in summer (July to August). The species richness was the lowest in October, but the abundance of the dominant species Aphodius rectus was significantly higher than that of all other species. The results of 16S rRNA based classification were consistent with morphological classification. The established evolutionary tree was divided into two distinct branches. The first branch contained 10 Aphodiinae species, which belonged to Dweller. The fecal disposal of species has obvious convergence. The second branch included nine species of Scarabaeidae and Geotrupidae. From the perspective of functional groups, there are seven Tunnelers and two Rollers. Although Onthophagus gibbulus, Onthophagus nuchicornis,Gymnopleurus mopsus, andGymnopleurus flayellates have close genetic relationship, they were belonged to two functional groups and showed interspecific divergence in fecal disposal.

Key words: dung beetle, species diversity, functional group, genetic relationship.