Welcome to Ticks of Australia

Australasia has a special place in the history of hard ticks (Ixodidae). Indeed, the hard ticks (Dobson & Barker 1999; Barker & Murrell 2002, 2004; Barker et al. 2021), soft ticks and nutalliellid ticks (Barker & Walker 2014) may have first lived in Australia, or more accurately, that part of the super continent Gondwana that became Australia, perhaps as early as 362-409 million years ago in the Devonian era. Accordingly, six of the eight subfamilies of ticks are endemic to Australia: Argasinae, Bothriocrotinae, Amblyomminae, Haemaphysalinae, Ixodinae and the Ornithodorinae. 

Only the subfamilies Nutalliellinae (the nutalliellid ticks) and Rhipicephalinae are not endemic to Australia. We speculate that the Nutalliellinae may well have lived in Australia (Barker et al. 2014), or might still be here, but certainly the Rhipicephalinae evolved elsewhere (probably in Africa) and much, much later (Murrell et al. 2001a). Whereas the Australian tick fauna is rich in subfamilies, it is depauperate in species: only 72 of the 900 or so species of ticks of the world are endemic to Australia. 

Furthermore, the earliest diverging lineage of the subfamily Ixodinae, the Australasian Ixodes clade, is endemic to Australasia (Barker & Murrell 2004). The closest living relatives to the ticks, the sister-group, seems to be the free-living holothyrid mites (Murrell et al. 2005 and references therein). Two hypotheses have been proposed: (i) an ancient origin (c. 390 m. y. a.) and vicariant dispersal during continental breakup (Dobson & Barker 1999); or (ii) recent origin (c.120 m. y. a.) and dispersal after the breakup of continents was almost complete (Klompen et al. 2000).