Apicomplexa is a large monophyletic phylum of unicellular, parasitic organisms. Reptiles are hosts to both haemosporidian (Haemosporida) and hemogregarine (Eucoccidiorida) apicomplexan blood parasites. Within reptiles our understanding of their diversity remains limited, with a paucity of information from Australia, despite a high diversity of squamates (snakes and lizards). We provide a preliminary assessment of haemosporidian and hemogregarine diversity occurring in lizards across northern tropical Australia, building on existing data with results from a microscopy and genetic assessment. We screened total of 233 blood slides using microscopy and detected hemogregarines in 25 geckos, 2 skinks and 1 agamid, while haemosporidians were detected in 13 geckos. DNA sequencing of 28 samples of the hemogregarine 18S rRNA (∼900 bp) nuclear gene revealed five lineages of Australian lizard hemogregarines within heteroxenous adeleids. We sequenced 10 samples of Haemosporida mtDNA (cytb & coI: ∼1313 bp) and phylogenetic analysis with 30 previously published sequences revealed that the Australian Haemosporida grouped within the Haemoproteidae but were not supported as a monophyletic clade. Our results demonstrate that there is significant undocumented evolutionary diversity in Australian lizard haemosporidian and hemogregarine parasites, with preliminary evidence of significantly higher infection rates in geckos.

The Bellinger River snapping turtle (Myuchelys georgesi) is endemic to Australia and is confined to a highly restricted distribution in the Bellinger River in New South Wales. Routine veterinary health examinations of 17 healthy turtles were undertaken, along with the collection and analysis of blood samples, during conservation efforts to save the species following a catastrophic population decline. Microscopy analysis of blood films detected Haemoproteidae parasites that morphologically resembled Haemocystidium chelodinae inside turtle erythrocytes. Of the 17 turtles examined, 16 were positive for infection with H. chelodinae by both light microscopy and PCR. DNA sequencing of a partial fragment of the mitochondrial cytochrome b (cytb) gene and phylogenetic analysis identified two different H. chelodinae-like genotypes. The phylogenetic relationship of H. chelodinae-like to other Haemoproteidae species based on cytb sequences grouped H. chelodinae-like into the reptile clade, but revealed the Haemocystidium genus to be paraphyletic as the clade also contained Haemoproteus, thus supporting a re-naming of Haemoproteus species from reptiles to Haemocystidium species. This study reports for the first time the genetic characterisation of H. chelodinae-like organisms isolated from a new Testudine host species, the Bellinger River snapping turtle. As evidence grows, further research will be necessary to understand the mode of transmission and to investigate whether these parasites are pathogenic to their hosts.

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