Isospora saimirae Lainson and Shaw, 1989.

Type host: Saimiri sciureus sciureus Linneaus, 1758, Squirrel monkey.

Other hosts: None reported to date.

Type locality: SOUTH AMERICA: Brazil, Pará State, Island of Tocantins (4º 49' S : 49º 49' W) ~75 km from Tucurui. Ironically, the type locality now lies beneath the waters of the Tucurui Reservoir, a man-made lake formed shortly after the discovery of this parasite by Lanison and Shaw (1989).

Geographic distribution: SOUTH AMERICA: Brazil, Pará State, Island of Tocantins.

Description of oocyst: Oocyst shape: subspheroid to ellipsoid; number of walls: 1; wall thickness: ~0.6; wall characteristics: smooth, colorless; L x W: 25.5 x 22.2 (24-27.5 x 19-24); L/W ratio: 1.1; M: absent; OR: absent; PG: absent. Distinctive features of oocyst: thin, 1-layered wall with OR and PG absent.

Description of sporocysts and sporozoites: Sporocyst shape: ellipsoid; L x W: 15.9 x 11.5 (15-16 x 11-12.5); L/W ratio: 1.4; SB: absent; SSB: absent; PSB: absent; SR: large, bulky compact mass composed of granules and spherules lying between SP; SP: elongate and curved within sporocyst. Distinctive features of sporocyst: SP without RB, that are longer than sporocyst and curved within it.

Prevalence: 2/12 (17%).

Sporulation: Exogenous. Oocysts sporulated within 24 hr at ~24ºC.

Prepatent and patent periods: Unknown.

Site of infection: Unknown. Oocysts recovered from feces.

Material deposited: None.

Remarks: The fate of the squirrel monkeys and all other fauna on Tocantins Island after the flooding is unknown. This species has not been seen since its original description.

Reference: Lainson and Shaw (1989).