Type host: Hyla arborea (L., 1758), European treefrog.

Other hosts: None reported to date.

Type locality: CAUCASIA.

Geographic distribution: CAUCASIA.

Description of oocyst: Oocyst shape: ovoidal to ellipsoidal; number of walls: 1 (line drawing); wall thickness: unknown; wall characteristics: not given; L x W: 21.4 x 17.6 (18-25 x 15-21); L/W ratio: 1.2; M: absent; OR: absent; PG: absent. Distinctive features of oocyst: none.

Description of sporocysts and sporozoite: Sporocyst shape: subspheroidal; L x W: 13 x 9; L/W ratio: 1.4; SB: absent; SSB: absent; PSB: absent; SR: present; SR characteristics: distinct (line drawing); SZ: elongate (8.9 x 4.4). Distinctive features of sporocysts: none.

Prevalence: Unknown.

Sporulation: Unknown, but Yakimoff (1930a) reported finding oocysts in a sporulated state in the intestinal contents.

Prepatent and patent periods: Unknown.

Site of infection: Unknown.

Endogenous development: Unknown.

Materials deposited: None.

Remarks: This is the only Isospora species described from a treefrog of the genus Hyla. Because most amphibian isosporans probably do not cross generic boundaries, we feel that Yakimoff’s (1930a, b) species is valid, but poorly described.