Giardia peramelis

Hillman, Alison, Ash, Amanda, Elliot, Aileen, Lymbery, Alan, Perez, Catherine & Thompson, R. C. Andrew, 2016, Confirmation of a unique species of Giardia, parasitic in the quenda (Isoodon obesulus), International Journal for Parasitology: Parasites and Wildlife 5 (1), pp. 110-115 : 114

4.1. Giardia peramelis taxonomic summary

Type host: I. obesulus- quenda (syn. southern brown bandicoot).

Mammalian additional hosts: unknown.

Type locality: Perth , Western Australia .

Additional locations: other locations in Western Australia ( Adams et al., 2004; Thompson et al., 2010).

Site of Infection: unknown; presumably small intestine, based on the known Giardia spp. site of infection in other mammalian hosts ( Monis et al., 2009).

Prepatent and patent periods: unknown.

Material deposited: A sample of formalin-preserved and ethanol-preserved G. peramelis cysts, and photomicrographs of G. peramelis cysts, were deposited at the Western Australian Museum (specimen registration no. WAM Z68785).

Etymology: The specific epithet peramelis is derived from the subfamily Peramelinae /family Peramelidae /order Peramelemorphia-taxonomic classifications of the quenda, the only confirmed host of G. peramelis . This is in line with current taxonomic nomenclature for Giardia spp. ( Monis et al., 2009).

This study confirms that G. peramelis (previously the ‘quenda genotype’ of Giardia ) is a unique species. Based on genotyping at 18s rRNA, all G. peramelis isolates in this study strongly aligned with the original ‘quenda genotype’ data, generated by Adams et al. (2004). We have further confirmed the genetic novelty of G. peramelis with genetic data obtained at ITS1-5.8S-ITS2, which identified G. peramelis as belonging to the genus Giardia but did not match any published sequences of Giardia spp. Phylogenetic analyses of both genes place G. peramelis external to the ‘ G. duodenalis species complex’ and external to G. microti . This supports the proposals of both Adams et al. (2004) and Thompson and Monis (2004, 2012) that G. peramelis is a novel lineage, distinct from described species.

The extreme mismatch observed between the G. peramelis 18S rRNA sequences reported here and in Adams et al. (2004), and the previously reported ‘quenda genotype’ (HQ398319) obtained from a calf ( Ng et al., 2011a), suggests that a partial ‘quenda genotype’ may have been sequenced from the calf, along with other genetic material.

As G. peramelis cysts are morphologically indistinguishable from several other species of Giardia , molecular characterisation is required to differentiate G. peramelis from other Giardia spp. Our results suggest that the 18S rRNA and ITS1-5.8s-ITS2 loci are the most successful target regions for this purpose.

The substantial number of quenda observed to be infected with G. peramelis , sampled across a large number of locations in this study, suggests that quenda are a natural host for G. peramelis .