A new species of Isospora (Apicomplexa: Eimeriidae) from eastern coachwhip, Coluber flagellum flagellum (Reptilia: Ophidia) from Oklahoma.

Between June 2013 and August 2014, four eastern coachwhips, Coluber flagellum flagellum were collected from Arkansas (n = 2) and Oklahoma (n = 2) and their faeces examined for coccidian parasites. One (25%) harboured an isosporan that we describe here as new. Oocysts of Isospora kiamichiensis sp. n. were spheroidal to subspheroidal with a uni-layered wall and measured (length × width, L × W) 25.0 × 22.2 μm, with an L/W ratio of 1.1. A micropyle, oocyst residuum and polar granule were absent. Sporocysts were ovoidal, 13.9 × 9.4 μm, with an L/W ratio of 1.5. A pronounced, button-like Stieda body was present as well as a substieda body. A sporocyst residuum was present as dispersed granules. This is the first isosporan and fourth coccidian reported from eastern coachwhip snakes. In addition, a single oocyst of an unknown choleoeimerian was recovered from this host.