A new eimerian (Apicomplexa: Eimeriidae) from southern short-tailed shrews, Blarina carolinensis (Bachman) (Soricimorpha: Soricidae: Soricinae) from southeastern Oklahoma, USA.

A new species of Eimeria Schneider, 1875 (Apicomplexa: Eimeriidae) is described from faecal samples of two of three southern short-tailed shrews, Blarina carolinensis (Bachman) (Soricidae) from southeastern Oklahoma, USA. Oöcysts of Eimeria tkachi n. sp. are subspheroidal to ovoidal with a rough-pitted, tan colored, bi-layered wall, measure 16.5 × 15.2 µm, and have a length/width (L/W) ratio of 1.1; both micropyle and oöcyst residuum are absent, but polar granule(s) are present. Sporocysts are ovoidal, 9.5 × 6.5 µm, L/W 1.4; a distinct button-like Stieda body is present, but the sub-Stieda and para-Stieda bodies are absent and the sporocyst residuum is composed of large globules distributed throughout the sporocyst. Sporozoites have a spheroidal anterior refractile body, a subspheroidal posterior refractile body, and one centrally-located nucleus. This is the smallest eimerian described thus far from the Soricidae, the initial description of a coccidian from B. carolinensis, and the first from any shrew from Oklahoma.