Abstract: | Fecal samples of 36 ground squirrels, Spermophilus beldingi, from Tioga Pass (elev. ca. 3315 m) in the Sierra Nevada, California, yielded oocysts of Eimeria beckeri in nine squirrels, E. citelli in four squirrels, E. beldingii n. sp. in two squirrels, and degenerated, unidentifiable oocysts in ten squirrels. Eimeria beldingii n. sp. oocysts are ellipsoidal, 30–34 × 24–30 (mean 32 × 26) μm with a two-layered, rough, striated wall, without a micropyle or residuum, with polar granules; they contain ellipsoidal or ovoid sporocysts 11–15 × 9–12 (mean 13 × 10) μm with a Stieda body and residuum. |