Type host: Spermophilus lateralis.

Synonyms: Eimeria beldingii; E. larimerensis; E. sarseni; E. tuscarorensis; E. wisconsinensis.

Other hosts: Cynomys gunnisoni; C. leucurus; C. ludovicianus; M. baibacina; M. bobak; M. monax; Spermophilus armatus; S. beecheyi; S. beldingi; S. columbianus; S. elegans; S. richardsonii; S. spilosoma; S. townsendii; S. tridecemlineatus; S. variegatus; T. obscurus; Tamias striatus.

Type locality: North America: USA, Arizona, Point Imperial on the north rim of the Grand Canyon, Grand Canyon National Park.

Other localities: Asia: Kazakhstan; North America: Canada, Alberta; USA, Arizona, California, Colorado, Idaho, Illinois, Massachusetts, Montana, New York, Pennsylvania, Utah, Wisconsin, Wyoming; Central America: Mexico, Baja California.

Description of oocyst: Oocyst shape: ellipsoid to ovoid; wall thickness: ~2; layers: 2; outer layer proportion of total thickness: 3/4; outer layer colour: yellow-brown; outer layer texture: rough; inner wall characteristics: smooth, pale; micropyle: absent; OR: absent; OR characteristics: present only during sporulation; PG: present; number of PGs: 1-14; PG shape: rounded; PG L x W: 1 x 1; size: 35.1 x 26.8 (28-40 x 24-31); L/W ratio: 1.3 (1.0-1.5). Distinctive features of oocyst: large size, thick outer wall and an OR that disappears during the sporulation process.

Description of sporocysts and sporozoites: Sporocyst shape: ovoid; size: 16 x 10; SB: present; SB L x W: not given; SB characteristics: prominent; SSB: absent; PSB: absent; SR: present; SR characteristics: large; numerous granules throughout sporocyst; SR size: not given; SP: rod-shaped. Distinctive features of sporocyst: SR that surrounds and almost obscures SP.

Material deposited: USNPC No. 87251 (phototype).

Remarks: Eimeria lateralis was described by Levine et al. (1957) in S. lateralis. In 1962, Dorney described what he called E. wisconsinensis (25.9-35.3 x 20.2-27.4) from T. striatus and in 1965 he described E. tuscarorensis (30.2-36.4 x 24.8-30.2) from M. monax. The oocysts of both species are indistinguishable from each other and from E. lateralis, but were given different names because they occurred in different host genera. Given the structural unity of these forms and the knowledge that marmotine Eimeria spp. can cross host generic boundaries, we believe it prudent to make both E. wisconsinensis and E. tuscarorensis junior synonyms of E. lateralis. Nukerbaeva & Abenov (1979) described E. sarseni (38 x 35) from M. baibacina; however, their photomicrograph showed a sporulated oocyst more ellipsoid than indicated by their measurements and it closely resembled E. tuscarorensis (= E. lateralis, see above). Although they mentioned E. tuscarorensis in their introduction, they failed to compare it to their new species. The oocysts they measured were slightly larger than E. lateralis, but appear to be the same species. Veluvelo & Levine (1986) described E. beldingii (30-37 x 25-31) from S. beldingi, but it does not differ in any substantive way from E. lateralis and, in our opinion, also should become a junior synonym. Recently, Seville & Stanton (1993a) synonymised E. larimerensis with E. lateralis, a decision with which we agree.

References: Broda & Schmidt (1978); Dorney (1962, 1963, 1965, 1966); Duncan (1968); Fleming et al. (1979); Hill & Duszynski (1986); Hilton & Mahrt (1971); Levine et al. (1957); McQuistion & Wright (1984); Nukerbaeva & Abenov (1979); Seville (1997); Seville & Stanton (1993a, b); Seville & Williams (1989); Seville et al. (1992); Shults et al. (1990); Stanton et al. (1992); Thomas & Stanton (1994); Todd & Hammond (1968b); Veluvolu & Levine (1984); Vetterling (1964); Wilber et al. (1994).