Hosts: Sheep, Rocky Mountain bighorn sheep. This species was originally described from the bighorn sheep, but Hawkins (in Morgan and Hawkins, 1952) found it in domestic sheep.
Location: Unknown. Oocysts found in feces.
Geographic Distribution: North America (Wyoming, Michigan).
Morphology: The oocysts are spherical to broadly ellipsoidal to ovoid, colorless to faint pink or greenish, and are 17 to 23 by 17 to 22 u with a mean of 21.9 by 19.4 u. Their length-width ratio is 1.00 to 1.35 with a mean of 1.11. A micropyle and micropylar cap are present. The micropylar cap measures from a trace to 1.7 u high and 3.3 to 6.6 u wide with a mean of 0.8 u high and 4.9 u wide. The oocyst wall has a distinctly demarcated outer edge, a feature which Honess (1942) considered to distinguish this species from E. arloingi. The sporocysts are 8 to 11 by 5 to 8 u with a mean of 9.5 by 6.4 u. No information is available on oocyst polar granule, oocyst residuum or sporocyst residuum.
Lotze (1953) considered that this species was of doubtful validity, since its oocysts fall into the size range of E. arloingi, but Morgan and Hawkins (1952) accepted it, stating that Hawkins had found that its peak of infection in Michigan occurred at a different time from that of E. arloingi.
Life Cycle: Unknown.