Mattesia is a genus of parasitic alveolates of the phylum Apicomplexa. Species in this genus infect insects (Coleoptera, Hymenoptera, Lepidoptera and Siphonaptera).
The genus was described in 1930 by Naville.
There are eight recognised species in this genus.
The type species is Mattesia geminata.
Coelogregarina Ghélélovitch, 1948 is a synonym of Mattersia.
Mattesia bombi has been moved to a new genus â Apicystis bombi.