MOLECULAR PHYLOGENETIC RELATEDNESS OF FRENKELIA SPP. (PROTOZOA, APICOMPLEXA) TO SARCOCYSTIS-FALCATULA STILES 1893 - IS THE GENUS SARCOCYSTIS PARAPHYLETIC

The coccidians Frenkelia microti and F. glareoli (Apicomplexa: Sarcocy stidae) form tissue cysts in the brain of small rodents (intermediate hosts) while oocysts are formed in the intestine of final hosts, buzza rds of the genus Buteo. The inclusion of the small subunit ribosomal R NA gene sequences (SSU rRNA) of both Frenkelia species into the SSU rR NA trees of other, tissue cyst-forming coccidia strongly supports para phyly of the genus Sarcocystis. Frenkelia spp. exhibit close relatedne ss to Sarcocystis falcatula Stiles 1893, a bird-opossum parasite, reco gnized under its junior synonym S. neurona Dubey et al. 1991, as the c ausative agent of equine protozoan myeloencephalitis on the American c ontinent. As the definition of the genus Frenkelia is based on a plesi omorphic character (affinity to the neural tissue) of supposedly low p hylogenetic value, the synonymization of the genus Frenkelia with Sarc ocystis is proposed. This renders the genus Sarcocystis monophyletic.