A specialised group of chytrids grow in the rumen of herbivorous animals, where they degrade cellulose and thus play a primary role in the complex microbial ecology of the rumen.

N. frontalis
N. hurleyensis
N. joyoni
N. patriciarum
N. variabilis

Neocallimastix is a genus of obligately anaerobic rumen fungi in the family Neocallimastigaceae.