Renal myxosporidiosis by an unknown Bivalvulidan myxozoan parasite in Murray River turtles (Emydura macquarii) in Australia

This case series provides the first published record of a myxozoan parasite in Murray River turtles (<i>Emydura macquarii</i>) in Australia. Thirteen turtles were captured for an eco-toxicology study and underwent postmortem examinations. From these, three were found to have interstitial nephritis and spores within the affected renal tubules. Molecular characterisation was performed with PCR which yielded positive results for myxozoan DNA in the three infected samples. DNA sequencing and phylogenetic analysis of 18S rRNA sequences positioned the unknown species in a distinct clade, closely related to, but separate from, histozoic clades II and III. This discovery contributes significantly to the understanding of myxozoan diversity and ecology, highlighting a potential new threat to the health of Murray River turtle populations and possibly other aquatic reptiles. The discovery of this myxozoan species not only broadens the known host range of myxozoans but also raises concerns about the conservation of affected turtle populations due to its possible pathogenic nature.