Molecular phylogeny of the other tissue coccidia: Lankesterella and Caryospora

Nearly complete sequences were obtained from the 18S rDNA genes of Eimeria falciformis (the type species of the genus), Caryospora bigenetica, and Lan kesterella minima. Two clones of the rDNA gene from C. bigenetica varied sl ightly in primary structure. Parsimony-based and maximum likelihood phyloge netic reconstructions with a number of other apicomplexan taxa support 2 ma jor clades within the Eucoccidiorida, i.e., the isosporoid coccidia (consis ting of Toxoplasma, Neospora, Isospora [in part], and Sarcocystis spp.) and a second clade containing Lankesterella and Caryospora spp., as well as th e eimeriid coccidia (Cyclospora, Isospora [in part], and Eimeria spp.). Our observations suggest that Caryospora spp. may not belong in the family Eim eriidae but rather may be allied with the family Lankesterellidae with whic h they share molecular and life history similarities. This may be a third l ineage of coccidian parasites that has independently evolved a unique heter oxenous transmission strategy.