Coccidia (Apicomplexa: Eimeriidae) Infecting Cricetid Rodents from Alaska, U.S.A., and Northeastern Siberia, Russia, and Description of a New <i>Eimeria</i> Species from <i>Myodes rutilus</i>, the Northern Red-Backed Vole

During the summers of 2000, 2001, and 2002, 1,950 fecal samples from 4 families, 10 genera, and 16 species of rodents in Alaska, U.S.A. (N1⁄41,711), and Siberia, Russia (N1⁄4239) were examined for coccidia (Apicomplexa: Eimeriidae). The 4 families sampled were Dipodidae (jumping mice), Erethizontidae (New World porcupines), Muridae (mice, rats), and Cricetidae (voles, lemmings). Nineteen oocyst morphotypes were observed, of which 10 were consistent with descriptions of known coccidia species from murid hosts, 8 were similar to oocysts described previously from other genera than those in which they are found here (and are called Eimeria species 1–8), and 1 is described as new. In the Dipodidae, all from Alaska, 0/15 Zapus hudsonius had coccidian oocysts in their feces when examined. In the Erethizontidae, all from Alaska, 0/5 Erethizon dorsatum had oocysts when examined. In the Muridae, all from Russia, 0/5 Apodemus peninsulae had oocysts when examined. In the Cricetidae from Alaska, we found the following infections: 15/72 (21%) Lemmus trimucronatus (Eimeria spp. 3, 4, 5); 10/29 (34%) Microtus longicaudus (Eimeria saxei, Eimeria wenrichi); 41/88 (47%) Microtus miurus (Eimeria coahiliensis, Eimeria ochrogasteri, Eimeria saxei, Eimeria wenrichi); 278/405 (68%) Microtus oeconomus (E. ochrogasteri, E. saxei, E. wenrichi); 116/159 (73%) Microtus pennsylvanicus (E. saxei, E. wenrichi); 9/52 (17%) Microtus xanthognathus (E. wenrichi); 218/699 (31%) Myodes rutilus (Eimeria cernae, Eimeria gallati, Eimeria marconii, Isospora clethrionomydis, Isospora clethrionomysis, and a new Eimeria species); 34/187 (18%) Synaptomys borealis (Eimeria spp. 6, 7, 8, Eimeria synaptomys). In the Cricetidae from Siberia, we found the following infections: 5/24 (21%) Alticola macrotis (Eimeria spp.1, 2); 0/5 Dicrostonyx torquatus; 1/11 (9%) Lemmus lemmus (Eimeria sp. 3); 30/48 (52%) Mi.oeconomus (E. saxei, E. wenrichi); 5/53 (9%) Myodes rufocanus (E. cernae, E. gallati, I. clethrionomydis, the new Eimeria sp.); 21/85 (25%) Myodes rutilus (E. cernae, E. gallati, E. marconii, the new Eimeria sp.); 0/8 Myopus schisticolor. Oocysts of the new species, found in both My. rutilus (Alaska, Siberia) and My. rufocanus (Siberia), are ellipsoidal with a striated outer wall and measured 30.6 3 20.5 (27–33 3 19–23) lm; micropyle and oocyst residuum absent, but a polar granule is present. Sporocysts are ellipsoidal, 14.5 3 9.1 (13–16 3 8–10) lm; Stieda body, sub-Stieda body and sporocyst residuum are present.