Eimeria maricopensis n. sp. (Apicomplexa: Eimeriidae) from the Arizona cotton rat Sigmodon arizonae Mearns (Rodentia: Cricetidae) in central Arizona, USA.

Eimeria maricopensis n. sp. (Apicomplexa: Eimeriidae) is described from 2 of 15 (13%) Arizona cotton rats Sigmodon arizonae Mearns in Arizona, USA. Sporulated oöcysts of this new species are ovoidal to ellipsoidal, 20-28 × 16-22 (24.9 × 19.2) µm, with a smooth, bi-layered wall; both micropyle and oöcyst residuum are absent, but fragmented polar granule material is present. Sporocysts are ellipsoidal, 11-14 × 6-8 (12.9 × 7.0) µm, with a Stieda body, sub-Stieda body, and sporocyst residuum; sporozoites are elongate with a spheroidal anterior refractile body and a subspheroidal posterior refractile body. In addition, sporulated oöcysts of Eimeria sigmodontis Barnard, Ernst & Dixon, 1974, Eimeria tuskegeensis Barnard, Ernst & Dixon, 1974 and Eimeria webbae Barnard, Ernst & Dixon, 1974 are described from S. arizonae. This is the first report on the coccidia of S. arizonae.