To investigate the anaerobic fungal diversity in the rumen of gayals (Bos frontalis),Yunnan yellow cattle,yaks,and Tibetan yellow cattle,the ITS region of ruminal anaerobic fungi was sequenced.The anaerobic fungi found in four types of cattle could be divided into 16 groups (Neocallimastix,Anaeromyces,Orpinomyces,Caecomyces,Cyllamyces and unknown groups 1-11).There were 10 anaerobic fungal groups in the rumen of gayals,with three belonging to known genera (Orpinomyces,Neocallimastix,and Caecomyces),which accounted for 2.8％ of sequences of gayals.There were fewer known anaerobic fungi in gayals than in Yunnan yellow cattle (Orpinomyces),yaks (Anaeromyces,Orpinomyces,and Cyllamyces) and Tibetan yellow cattle (Anaeromyces,Orpinomyces,Caecomyces,and Cyllamyces),accounting for 30.7％,93.9％,and 35％ of each of the relevant cattle species.The other seven unknown groups (NG1,NG4,NG6,NG7,NG9,NG10,and NG11) accounted for 91.6％ of sequences from gayals,which was higher than Yunnan yellow cattle [69.3％ (NG2,NG8 and NG9)],Tibetan yellow cattle [35％ (NG4,NG5 and NG9)],and yaks [6.1％ (NG3)].Furthermore,NG1,NG6,NG7,NG10,and NG11 were only found in gayals,whereas NG3 and NG5 were found only in Tibetan yellow cattle and yak,respectively.Piromyces was not found in any of the four types of cattle.The anaerobic fungi abundance in the rumen of gayals was significantly higher than that of the other three types of cattle.The ruminal anaerobic fungi of gayals might have an important role in cellulose degradation,resulting in the ability of this species to successfully graze coarser fodder.