# Unresolved haemosporidia of the Australian skink, Egernia stokesii

## TL;DR

This study investigates the haemosporidian parasites in the Australian skink Egernia stokesii, revealing conflicting results between molecular and morphological analyses.

## Contribution

The study highlights the challenges in identifying haemosporidian species due to conflicting molecular and morphological data.

## Key findings

- Molecular data clustered isolates with Haemocystidium, but morphology resembled Plasmodium.
- Limited sampling and indistinguishable nuclei/merozoites hindered species identification.
- Mixed infections may be present but cannot be confirmed with current data.

## Abstract

The Australian skink Egernia stokesii had been recognised as a host of two species of Plasmodium, Plasmodium mackerrasae and P. circularis; nevertheless, molecular data are available for only a single haemosporidian species of this host. Its sequences are labelled as “Plasmodium sp.” or “Plasmodium mackerrasae”, but morphological characteristics of this isolate are unavailable. Phylogenetic analyses of these sequences placed them into the clade of the genus Haemocystidium. In this study, blood samples of six E. stokesii were analysed by both, molecular and microscopic methods to clarify the haemosporidia of this lizard. Application of these approaches offered discordant results. Whereas sequence analysis clustered our isolates with lizard species of Haemocystidium, morphology of blood stages is more akin to Plasmodium than Haemocystidium. However, limited sampling, indistinguishable nuclei/merozoites and risk of possible hidden presence of mixed infection prevent reliable species identification of detected parasites or their description as new species of Haemocystidium.