Comparison of the ITS1 and ITS2 rDNA in Eimeria callospermophili (Apicomplexa:Eimeriidae) from sciurid rodents.

The taxonomy of the coccidia has historically been morphologically based. The purpose of this study was to establish if conspecificity of isolates of Eimeria callospermophili from 4 ground-dwelling squirrel hosts (Rodentia: Sciuridae) is supported by comparison of rDNA sequence data and to examine how this species relates to eimerian species from other sciurid hosts. Eimeria callospermophili was isolated from 4 wild-caught hosts, i.e., Urocitellus elegans, Cynomys leucurus, Marmota flaviventris , and Cynomys ludovicianus . The ITS1 and ITS2 genomic rDNA sequences were PCR generated, sequenced, and analyzed. The highest intraspecific pairwise distance values of 6.0% in ITS1 and 7.1% in ITS2 were observed in C. leucurus. Interspecific pairwise distance values > 5% do not support E. callospermophili conspecificity. Generated E. callospermophili sequences were compared to Eimeria lancasterensis from Sciurus niger and Sciurus niger cinereus and to Eimeria ontarioensis from S. niger. A single, well-supported clade was formed by E. callospermophili amplicons in neighbor joining and maximum parsimony analyses. However, within the clade, there was little evidence of host or geographic structuring of the species.

Species of Eimeria (Apicomplexa: Eimeriidae) from tree squirrels (Sciurus niger) (Rodentia: Sciuridae) and analysis of the ITS1, ITS2, and 5.8S rDNA.

During the winter of 2004, 48 fecal samples were collected from live-trapped fox squirrels (Sciurus niger) from central Wyoming (Natrona County) and examined for species of Eimeria. Two species, Eimeria lancasterensis (prevalence, 65%) and Eimeria ontarioensis (prevalence, 27%), were identified. Genomic DNA sequences ITS1 and ITS2 were amplified, cloned, and sequenced. Additional sequences from E. lancasterensis isolated from a Delmarva fox squirrel (Sciurus niger cinereus) collected on Chincoteague Island, Virginia, were also identified. Comparison of pairwise distances suggests that E. lancasterensis from Wyoming and Virginia are conspecific. Maximum Parsimony tree construction identified 2 lineages, one E. ontarioensis and one E. lancasterensis; and both lineages had a strong bootstrap support (100%). The Maximum Parsimony analysis was unable to resolve the Wyoming and Virginia strains.