Species of Coccidia (Apicomplexa: Eimeriidae) in Shrews From Alaska, U.S.A., and Northeastern Siberia, Russia, with Description of Two New Species

Fecal samples (n = 636) from 10 species of shrews collected in Alaska (n = 540) and northeastern Siberia (n = 96) were examined for the presence of coccidia (Apicomplexa: Eimeriidae). Five distinct oocyst morphotypes were observed. Three types were consistent with oocysts of previously recognized coccidia species from other shrew hosts. These were Eimeria inyoni, E. vagrantis, and Isospora brevicauda, originally described from the inyo shrew (Sorex tenellus), dusky shrew (S. monticolus), and northern short-tailed shrew (Blarina brevicauda), respectively. We found 5 new host records for E. inyoni, 3 for E. vagrantis, and 3 for I. brevicauda. The 2 additional oocyst morphotypes, both from the tundra shrew (Sorex tundrensis), are putative new species. Sporulated oocysts of Eimeria beringiacea n. sp. are subspheroidal, 17.7 × 15.6 μm (14–24 × 13–20 μm) with a length (L)/width (W) ratio of 1.1 (1.0–1.4); these lack a micropyle (M), an oocyst residuum (OR), and a polar granule (PG). Sporocysts are ellipsoidal, 10.3 × 6.1 μm (7–14 × 4–8 μm), with a L/W ratio of 1.7 (1.3–2.3) and have a Stieda body (SB), Substieda body (SSB), and sporocyst residuum (SR). Oocysts of Eimeria tundraensis n. sp. are spheroidal to subspheroidal, 24.8 × 23.5 μm (23–26 × 22–25 μm), with a L/W ratio of 1.1 (1.0–1.2); these lack a M and OR, but a single PG is present. Sporocysts are elongate ellipsoidal, 15.4 × 8.3 μm (13–17 × 7–9 μm), with a L/W ratio of 1.9 (1.4–2.1) and have a SB, SSB, and SR.