Type host: Lagostomus maximus (Plains vizcacha).

Type locality: SOUTH AMERICA: Argentina, La Pampa Province, Los Valles Ranch, 39º 11' 0.00" S, 63º 42' 31.9".

Geographic distribution: SOUTH AMERICA: Argentina.

Description of oocyst: Oocyst shape: ellipsoidal to subspheroidal; number of walls: 2; wall thickness: 1.5; wall characteristics: outer layer rough, yellowish-brown, ~1, inner smooth, colorless; L x W: 35.7 x 30.9 (26-36 x 30-41); L/W ratio: 1.2 (1.1-1.3); M: absent; OR: present; OR characteristics: round, consisting of many compact small granules, ~5.4-9; PG: absent. Distinctive features of oocyst: large size and distinct OR.

Description of sporocysts and sporozoites: Sporocyst shape: lemon-shaped; L x W: 14.2 x 10.2 (9-11 x 11-16); L/W ratio: 1.4 (1.2-1.7); SB: present, bluntly pointed; SSB: present as a broad extension of the inner membrane of sporocyst; PSB: absent; SR: present; SR characteristics: a few medium-sized granules lying horizontally along the middle of sporocysts; SP: fairly indistinguishable, but globular RB appear at each end of sporocyst. Distinctive features of sporocyst: none.

Prevalence: 17 of 163 (10%).

Sporulation: Probably exogenous. Oocysts sporulated within 1 wk in 2% aqueous (w/v) potassium dichromate solution at 24 C.

Prepatent and patent periods: Unknown.

Site of infection: Unknown. Oocysts recovered from feces.

Materials deposited: Photosyntypes of sporulated oocysts deposited in the U.S. National Parasite Collection (USNPC), Beltsville, MD, no. 90197.

Remarks: Only 1 other eimerian, E. chinchillae De Vos and Van der Westhuizen, 1968, has been described in the Chinchillidae from Chinchilla laniger. Sporulated oocysts of E. lagostomi differ from those of E. chinchillae by being larger, 25.7 x 30.9 versus 17.5 x 15.5, by having a rough outer wall, and by having a SSB that E. chinchillae lacks.

References: Couch et al. (2001).