Isospora daphnensis n. sp. (Apicomplexa: Eimeriidae) from the medium ground finch (Geospiza fortis) from the Galapagos Islands.

In March and April 1987 fecal samples from 237 nestling birds, including 199 from 85 nest sites of Geospiza fortis, 23 from 12 nest sites of Geospiza scandens, 6 from 2 nest sites of Geospiza magnirostris, and 9 from 2 nest sites of hybrids involving Geospiza fuliginosa and G. fortis, were collected from Daphne Major in the Galapagos archipelago and examined for coccidia. Only 3 of 4 nestlings from 1 nest site of G. fortis (1.5%) had oocysts in their feces. Two of the 3 infected nestlings had concurrent infections of Isospora temeraria, and all 3 nestlings were infected with a new species. Isospora daphnensis n. sp. Sporulated oocysts of I. daphnensis n. sp. are ellipsoidal, 27.3 x 23.6 (22-30 x 20-27) microns; a polar body is present, but no oocyst residuum or micropyle occurs. The oocyst wall, approximately 1.5 microns thick, is composed of a mammillated outer layer and thinner inner layer. Sporocysts are ovoid, 15.2 x 10.2 (15-16 x 9-11) microns and have a nipplelike Stieda body and a small substieda body. The sporocysts contain an irregularly shaped, smoothly contoured residuum with uniform granules and 4 sporozoites with a large refractile body at one end and lying randomly in the sporocysts.