Phylogenetic relationships among rodent Eimeria species determined by plastid ORF470 and nuclear 18S rDNA sequences.

Phylogenetic analyses for 10 rodent Eimeria species from different host genera based on plastid ORF470 and nuclear 18S rDNA sequences were done to infer the evolutionary relationships of these rodent Eimeria species and their correlation to morphology and host specificity. The phylogenies based on both data sets clearly grouped the 10 rodent Eimeria species into two major lineages, which reflect more their morphological differences than host specificity. Species in lineage A have spheroidal to subspheroidal sporulated oocysts, are similar in size (18-29 x 17-23; xbar = 22 x 20 microm), have an oocyst residuum and one-two polar granules; these include Eimeria albigulae (Neotoma), Eimeria arizonensis (Peromyscus, Reithrodontomys), Eimeria onychomysis (Onychomys) and Eimeria reedi (Perognathus). Species in lineage B, including Eimeria falciformis (Mus), Eimeria langebarteli (Reithrodontomys), Eimeria nieschulzi (Rattus), Eimeria papillata (Mus), Eimeria separata (Rattus) and Eimeria sevilletensis (Onychomys) have different shapes (ovoid, ellipsoid, elongated ellipsoid, etc.), differ greatly in size (10-27 x 9-24; xbar = 19 x 16 microm) and all lack an oocyst residuum. Thus, The oocyst residuum was the most determinant feature that differentiated the two lineages. The accession numbers of ORF470 of E. albigulae, E. arizonensis, E. falciformis, E. nieschulzi, E. onychomysis, E. papillata, E. reedi, E. separata, E. sevilletensis, E. langebarteli are AF311630-AF311639 and 18S rDNA of E. langebarteli, E. papillata, E. reedi, E. separata, E. sevilletensis are AF311640-AF311644.