Molecular characterization of and provides insight into the evolution and host specificity of avian piroplasmids.

There are 16 recognized species of avian-infecting spp. (Piroplasmida: Babesiidae). While the classification of piroplasmids has been historically based on morphological differences, geographic isolation and presumed host and/or vector specificities, recent studies employing gene sequence analysis have provided insight into their phylogenetic relationships and host distribution and specificity. In this study, we analyzed the sequences of the 18S rRNA gene and ITS-1 and ITS-2 regions of two species from South African seabirds: from African penguins () and from Bank and Cape cormorants ( and , respectively). Our results show that avian spp. are not monophyletic, with at least three distinct phylogenetic groups. and are closely related, and fall within the same phylogenetic group as (from herons ), (from boobies spp.) and (from murres ). The validity of and as separate species is corroborated by both morphological and genetic evidence. On the other hand, our results indicate that might be a synonym of , which in turn would be a host generalist that infects seabirds from multiple orders. Further studies combining morphological and molecular methods are warranted to clarify the taxonomy, phylogeny and host distribution of avian piroplasmids.