Two new coccidian parasites from the slate-colored grosbeak (Pitylus grossus) of South America.

In July and August 1990, fecal samples from 2 slate-colored grosbeaks were collected from the rain forest of Ecuador. Upon examination, 2 new species of coccidia were discovered. Oocysts of Isospora pityli n. sp. are spheroid or subspheroid, 20.1 x 18.8 (20-20.5 x 17-20) microns, with a shape index of 1.07 (1.0-1.18) but lacking a micropyle, oocyst residuum, and polar granules. Sporocysts are ovoid, 14.7 x 9.4 (12-17 x 8-11) microns, with small nipplelike Stieda bodies, no substieda bodies, and residua composed of an amorphous cluster of coarse, nonuniform granules. Sporozoites each possess a large refractile body at 1 end and appear to be enclosed in a thin membrane within the sporocyst along with the residuum. Oocysts of L. formarum n. sp. are spheroid or subspheroid, 24.6 x 23.5 (21-27 x 20-25) microns, with a shape index of 1.05 (1.0-1.09) but with no micropyle, oocyst residuum, or polar granules. Sporocysts are ovoid, 15.7 x 11.3 (14-17 x 10-13) microns, with small, nipplelike Stieda bodies and large triangular or conical-shaped substieda bodies with irregular lower edges. Sporozoites each possess an oblong refractile body at 1 end and appear packed together randomly and enclosed in a membrane along with a spheroid residuum composed of fine, uniform granules.