During September 2004, 4 adult northern myotis, Myotis septentrionalis, were collected from LeFlore County, Oklahoma (n  =  2), and Logan (n  =  1) and Yell (n  =  1) counties, Arkansas, and their feces examined for coccidian parasites. Three of 4 bats (75%) were passing oocysts of Eimeria spp. Oocysts of Eimeria tumlisoni n. sp. were subspherical, 17.6 × 16.8 (16–19 × 14–18) µm with a shape index of 1.0 (1.0–1.1). A micropyle and oocyst residuum were absent, although 1–2 bilobed polar granules were often present. Sporocysts were ovoidal, 10.5 × 5.9 (9–12 × 5–7) µm with a shape index of 1.8 (1.6–2.0). A Stieda body was present, but substieda and parastieda bodies were absent. A sporocyst residuum was present consisting of compact to dispersed granules between the sporozoites. The sporozoites were elongate, with subspherical anterior refractile body and spherical posterior refractile body; a nucleus was not discernable. This is the second coccidian reported from this host and the first instance of a bat coccidian reported from Oklahoma. We also document a new geographic record for Eimeria catronensis in Oklahoma and provide an emended description.