Two new species of coccidia, Eimeria leucuri and E. oreoecetes (Protozoa: Eimeriidae), in grouse from Colorado.

Eimeria leucuri is described from white-tailed ptarmigan (Lagopus leucurus), and E. oreoecetes from white-tailed ptarmigan and blue grouse (Dendragapus obscurus) from Colorado. Oocysts of E. leucuri are ellipsoidal, 26.6 by 17.7 micron, each bearing a micropyle, micropyle cap, up to 4 polar granules, but no oocyst residuum. The lemon-shaped sporocysts are 15.4 by 6.7 micron, and have Stieda bodies and large amounts of sporocyst residuum. The sporocyst contents are enclosed in a membrane. Oocysts of E. oreoecetes are subspherical, 26.0 by 22.6 micron, and have up to 4 polar granules. The lemon-shaped sporocysts are 14.6 by 8.8 micron, and have both Stieda bodies and substiedal bodies and a large amount of sporocyst residuum. The sporocyst contents are enclosed in a membrane. These are the first coccidia to be described from these tetraonids.