The novel anaerobic fungus Buwchfawromyces eastonii gen. nov., sp. nov., belonging to order Neocallimastigales (phylum Neocallimastigomycota) is described. Morphologically similar to Piromyces but genetically quite distinct, this fungus (isolate GE09) was first isolated from buffalo faeces in west Wales and then subsequently isolated from sheep, cattle and horse in the same area. Phylogenetic analysis of LSU and ITS sequence confirmed that B. eastonii isolates formed a distinct clade close to the polycentric Anaeromyces spp. The morphology of GE09 is monocentric with monoflagellate zoospores. However, the sporangial stalk (sporangiophore) is often distinctly swollen and the proximal regions of the rhizoidal system twisted in appearance.