Description of the female, nymph and larva and mitochondrial genome, and redescription of the male, of Ixodes barkeri Barker, 2019 (Acari: Ixodidae) from the short-beaked echidna, Tachyglossus aculeatus, with a consideration of the most suitable subgenus for this tick

Background: Ixodes barkeri , a tick with a distinctive ventrolateral horn-like projection on palpal segment 1, was described in 2019 from two male ticks from the Wet Tropics of Far North Queensland, Australia. However, females lie at the core of the taxonomy and subgenus classification of Ixodes , hence we sought specimens of female ticks, successfully recovering females, plus nymphs and larvae. Mitochondrial genomes are also desirable additions to the descriptions of species of ticks particularly with regard to subgenus systematics. So, we sequenced the mt genomes of I. barkeri Barker, 2019 and the possible relatives of I. barkeri that were available to us ( I. australiensis Neumann, 1904, I. fecialis Warburton & Nuttall, 1909, and I . woyliei Ash et al. 2017) with a view to discovering which if any of the subgenera of Ixodes would be most suitable for I. barkeri Barker, 2019. Results The female, nymph, larva, and mitochondrial genome of Ixodes barkeri Barker, 2019 are described for the first time and the male of I. barkeri is redescribed in greater detail than previously. So far, I. barkeri is known only from a monotreme, the short-beaked echidna, Tachyglossus aculeatus (Shaw, 1792), from the highland-rainforests of Far North Queensland, Australia. Conclusions Our phylogeny from entire mitochondrial genomes indicated that I. barkeri , and indeed I. woyliei Ash et al. 2017, another tick that was described recently, are best placed in the subgenus Endopalpiger Schulze, 1935.