Isospora formarum McQuistion & Capparella, 1992

Type host: Pitylus grossus grossus (Slate-colored grosbeak)

Other Hosts: Pitylus grossus saturates

Type locality: SOUTH AMERICA: Ecuador, Provincia de Morona-Santiago, ca. 5 km SW of Taisha, elev. 425 m.

Geographic distribution: SOUTH AMERICA: Ecuador, Provincia de Morona-Santiago and Prov. de Esmeraldas.

Description of oocyst: Oocyst shape: spheroid to subspheroid; number of walls: 2; wall thickness: ~1.5; wall characteristics: smooth, colorless outer surface with darker, thinner inner layer; L x W: 24.6 x 23.5 (20-25 x 21-27); L/W ratio: 1.1 (1.0-1.1); M: absent; OR: absent; PG: absent. Distinctive features of oocyst: lack of M, OR, and PG.

Description of sporocysts and sporozoites: Sporocyst shape: ovoid; L x W: 15.7 x 11.3 (10-13 x 14-17); L/W ratio: 1.4 (1.2-1.5); SB: present as small, nipple-like body; SSB: present, large and triangular-shaped or large and conical with irregular lower edge; PSB: absent; SR: present; SR characteristics: large, ~7 in diameter, nearly spheroid, composed of fine, uniform granules; SP: elongate with oblong RB at 1 end and arranged randomly in sporocyst. Distinctive features of sporocyst: SP and SR appear to be enclosed in a thin membrane within sporocyst.

Prevalence: 2 of 2 (100%).

Sporulation: Exogenous. Oocysts were stored in 2.5% (w/v) aqueous potassium dichromate solution at ambient temp. prior to examination.

Prepatent and patent periods: Unknown.

Site of infection: Unknown. Oocysts found in feces.

Materials deposited: None.

Remarks: This species has not been reported since its original description.

Reference: McQuistion & Capparella (1992).