Cryptic species diversity in ticks that transmit disease in Australia

We report here the application of molecular methods to examine the species diversity of ixodid ticks at two sites in southern New South Wales, Australia. Our taxon sampling included six morphologically characterised adult stage voucher specimens of Ixodes trichosuri, Ixodes tasmani, Ixodes fecialis and Ixodes holocyclus (the paralysis tick) and ∼250 field collected specimens that were in the larva or nymph stage and thus not morphologically identifiable. One nuclear and two mitochondrial amplicons were sequenced using a combination of Sanger and Illumina MiSeq sequencing. Phylogenetic relationships were estimated using both maximum likelihood and Bayesian methods. Two clades with strong bootstrap and Bayesian support were observed across trees estimated from each of three markers and from an analysis of the concatenated sequences. One voucher specimen of I. trichosuri was located in one of these clades, while the other I. trichosuri voucher specimen was in a second clade with the remaining three identified species, suggesting these morphologically similar ticks may represent different cryptic species. Unidentified specimens were found across both clades, and molecular divergence of many of these is equal to or greater than that observed between identified species, suggesting additional unidentified species may exist. Further studies are required to understand the taxonomic status of ticks in Australia, and how this species diversity impacts disease risk for livestock, domes...
Source: International Journal for Parasitology: Parasites and Wildlife - Category: Parasitology Source Type: research