Morphology and molecular phylogeny of selected haemoprotozoan parasites of Australian wildlife

Current information on the identity and kinship of haemoprotozoan parasites in Australian wildlife is sparse and fragmentary. Relatively few hosts have been properlynexamined and the pleomorphy of blood stage parasites has confounded theirnidentification. The aims of this study were to diagnose haemoprotozoan infections innvarious wildlife assemblages, describe their morphological and ultrastructuralncharacteristics, and infer phylogenetic relationships between parasite groups bynsequence analyses of small subunit ribosomal RNA (ssrRNA).nn n A total of 535 native Australian animals belonging to 17 families werensurveyed for the presence of blood parasites by haematological examination of bloodnfilms. Animals examined included 293 reptiles (213 snakes, 53 tortoises and 27nlizards), 16 amphibians (frogs and toads) and 226 mammals (165 bandicoots, 22nmacropodids, 33 platypuses, 2 possums, 2 dasyurids and 2 echidnas). The overallnprevalence of blood parasites was 42%, with 72 animals being infected withntrypanosomes, 140 with haemogregarines, 9 with haemoproteids and 3 withnmicrofilariae. Morphometric studies facilitated the identification of 6 parasite speciesn(2 Trypanosoma spp., 1 Haemogregarina sp., 2 Hepatozoon spp. and 1 Haemoproteusnsp.), but considerable morphological variation was detected both within and amongnparasite species, and even genera.n n Transmission electron microscopy was conducted on representative taxa tonexamine subcellular features and determine membrane and organelle character statesnfor cladistic phylogenetic analyses. The analyses confirmed monophyly of macroassemblagesn(family and genus) but species relationships were confounded by a lacknof biological data, especially regarding the identity of vectors and sexual developmentnin these vectors. Consequently, genotypic characters were determined by sequencingnssrRNA from representative taxa, including Haemogregarina clelandi, Haemoproteusnchelodina and Trypanosoma chelodina from tortoises, Trypanosoma binneyi from anplatypus, and haemogregarines from brown tree snakes, slaty grey snakes, amythestinenpythons and black-headed snakes. Maximum parsimony and distance matrix methodsnindicated that snake haemogregarines were in fact Hepatozoon.n n Phylogenetic analyses on trypanosomes isolated from platypuses and tortoisesnin this study showed that these organisms had a close affinity with the leech-vectoredntrypanosomes parasitizing bony and cartilaginous fish. The probable vectors for bothntortoise and platypus trypanosomes are also leeches and, given the diversity of thenvertebrate hosts parasitized by these organisms, it is more likely that co-evolution ofntrypanosomes relates more to the vectors rather than to the vertebrate hosts.n