RESUMO
In 1999, a single specimen of the Tolai hare, Lepus tolai Pallas, 1778, from the Gobi region of Mongolia was examined and had a new species of eimerian parasite in its intestinal contents. Eimeria gobiensis n. sp. is relatively large; it possesses 2 oocyst walls and a very well-developed oocyst residuum. Oocysts of the new species possess a thick wall with a double layer, a massive 3-layered micropyle, and are ellipsoidal, with average length and width of the oocyst of 38.6 × 24.2 µm, respectively. The range in measurements of these oocysts extends from 27.3 to 49.2 µm in length by 18.8 to 32.5 µm in width, with a length/width ratio = 1.6; the oocyst residuumis is composed of a sub-spheroidal mass of small granules with an average size of 12.0 × 11.0 µm; sporocysts are ovoidal with an average length × width of 15.0 × 7.7 µm, respectively, and a range in length extending from 9.2 to 21.0 µm by 5.0 to 12.0 µm in width. In addition, each sporozoite has a large, medial, refractile body with an average size of 6.0 × 5.0 µm.