Synonyms: E. dorsalis; E. morainensis; E. perforoides.

Type host:Eimeria adaensis.

Other hosts: Cynomys leucurus; C. ludovicianus; Marmota monax; Spermophilus mexicanus; S. townsendii; Tamias canipes; T. dorsalis; T. merriami; T. obscurus; T. striatus; T. townsendii.

Type locality: North America: USA, Wisconsin, Vilas County, Trout Lake.

Other localities: Central America: Mexico, Baja California; North America: USA, Arizona, California, Idaho, Illinois, Massachusetts, New Mexico, New York, Pennsylvania, Texas, Washington.

Description of oocyst: Oocyst shape: subspheroid to ellipsoid; wall thickness: 0.7-1.3; layers: 2; outer layer proportion of total thickness: ~3/4; outer layer colour: yellow-green; outer layer texture: smooth; inner wall characteristics: smooth, dark tan; micropyle: absent; OR: absent; PG: sometimes present; number of PGs: 0-6; PG shape: bilobed (in drawing); PG L x W: ~1.5; size: 17.6 x 14.3 (12-23 x 7-19); L/W ratio: 1.2. Distinctive features of oocyst: inner wall thins at one end; PGs distributed irregularly throughout oocyst; shadow at tapered end (Wilber et al., 1994; Hill & Duszynski, 1984).

Description of sporocysts and sporozoites: Sporocyst shape: ellipsoid; size: 10.1 x 5.6; SB: present; SB L x W: not given; SB characteristics: small, can be inconspicuous; SSB: absent; PSB: absent; SR: present; SR characteristics: well-defined, tight sphere or elongated mass of granules; SR size: not given; SP: posterior end slightly curled, clear RB in posterior end. Distinctive features of sporocyst: none.

Material deposited: USNPC No. 82931 (phototype).

Remarks: Eimeria vilasi was described from T. striatus by Dorney (1962). In 1965, Dorney found what he called E. perforoides in M. monax, but we believe the form he saw was E. vilasi because he did not observe an oocyst residuum, and the measurements and qualitative features are similar to those of E. vilasi (12-23 x 7-19 vs. 20-25 x 16-20). Fleming et al. (1979) and McQuistion & Wright (1984 later reported E. perforoides from M. monax, but they used Dorney (1965) to aid their identifications; thus, they probably saw E. vilasi. Hill & Duszynski (1986) described E. dorsalis (17-24 x 14-20) in several Tamias spp., but their photomicrographs and mensural data suggest it is best to synonymize that name with E. vilasi. Likewise, Wilber et al. (1994) described E. adaensis (18-26 x 16-22) from S. townsendii. However, E. adaensis and E. vilasi are so similar that the former should become a junior synonym. Wilber et al. (1994) suggested that the eimerian species described as E. morainensis by McAllister et al. (1991) was E. adaensis (= E. vilasi) because key features of E. morainensis were absent from the oocysts of McAllister et al. (1991). In summary, we suggest that E. adaensis, E. dorsalis, and E. perforoides (sensu Dorney, 1965) are the same as E. vilasi and should be considered junior synonyms because there is significant similarity in: 1) size of their oocysts and sporocysts; 2) wall characteristics (dark inner layer, thinning and shadow at tapered end; this was not reported in E. vilasi, but there was no photomicrograph and the drawing is of marginal quality); and 3) the sporocyst residuum (compact mass of granules).

References: Dorney (1962, 1963, 1965, 1966); Duncan (1968); Fleming et al. (1979); Hill & Duszynski (1986); McAllister et al. (1991); McQuistion & Wright (1984); Seville (1997); Wilber et al. (1994).