A new species of tick (Acari: Ixodidae) from seabirds in New Zealand and Australia, previously misidentified as Ixodes eudyptidis

Abstract

The tick Ixodes eudyptidis Maskell, 1885 has long been recognised as a parasite of penguins and a number of other seabird hosts and, despite a convoluted taxonomic history, there has been no disagreement as to its validity. The opportunity to examine a larger series of ticks from a wider range of hosts than previously available has led to the finding of a morphologically close and hitherto undescribed species, which is herewith described and named as Ixodes laridis sp.nov. The new species has a superficial similarity to its sibling, I. eudyptidis, but on close examination it displays a number of morphological differences that justify its taxonomic separation. Also, the hosts of the new species are principally gulls, gannets and cormorants, while I. eudyptidis is restricted to penguins. The recognition of this new species has implications for faunal lists in both New Zealand and Australia, as well for seabird health, as it appears that I. eudyptidis does not cause paresis as originally thought, but it is I. laridis that causes potentially fatal paralysis in its hosts. A taxonomic history and review of I. eudyptidis and keys to all stages of the species of Ixodes recorded from New Zealand, and from Australian seabirds are given. Reference to Ixodes kohlsi Arthur, 1955, a species currently restricted to Australia, is made for comparative purposes because of the similarity of both its morphology and host associations with the other species under consideration. Aspects of the distribution, zoogeography, hosts and ecology of all three species of ticks are discussed.

Tandem host‐parasite dispersal inferred from similarities in phylogeographical patterns among Little Penguins and their ‘terrestrial’ ectoparasites

“…Unlike Ixodes kohlsi, which has never been recorded from New Zealand, I. eudyptidis is found in both Australia and New Zealand (Roberts, 1970). Our mitochondrial and genomic data also provide the first evidence that I. kohlsi is present in western Australian colonies, as the penguins in the west were thought to be exploited by I. eudyptidis (Heath & Palma, 2017;Roberts, 1970).…”

“…Our mitochondrial and genomic data also provide the first evidence that I . kohlsi is present in western Australian colonies, as the penguins in the west were thought to be exploited by I. eudyptidis (Heath & Palma, ; Roberts, ).…”

“…In Australia, there are few flying seabird species that nest sympatrically with Little Penguins; the short‐tailed shearwater is, however, commonly found close to Little Penguins colonies, and also burrow‐nests, thus representing the best test of potential host specificity. Australian and New Zealand seabird tick taxonomy is poorly resolved (Heath & Palma, ), and so host records cannot be relied upon to resolve host range (McCoy, Léger, & Dietrich, ). Our results might further support a recent taxonomic revision that has described a new tick species ( I. laridis ) on flighted seabirds in New Zealand and Australia, which was erroneously recorded as I. eudyptidis (Heath & Palma, ).…”

“…Australian and New Zealand seabird tick taxonomy is poorly resolved (Heath & Palma, ), and so host records cannot be relied upon to resolve host range (McCoy, Léger, & Dietrich, ). Our results might further support a recent taxonomic revision that has described a new tick species ( I. laridis ) on flighted seabirds in New Zealand and Australia, which was erroneously recorded as I. eudyptidis (Heath & Palma, ). Ixodes laridis is known to occur on birds in Tasmania, and might be the species present on Wedge Island short‐tailed shearwaters.…”

“…If Little Penguin ticks are not host-species specific, their dispersal could be facilitated by flighted seabird hosts. Although some Little Penguin ticks have been recorded on non-penguin hosts (Roberts, 1970), new evidence suggests these records could be the result of poorly resolved taxonomy, and are likely to represent distinct species (Heath & Palma, 2017). Ixodes uriae, which parasitises diverse seabirds in the sub-Antarctic and Antarctic, has evolved host-specific races among different seabird species (McCoy et al, 2012;McCoy, Chapuis, et al, 2005) that can endure for long periods (Dietrich, Kempf, Boulinier, & McCoy, 2014), and is not found on other sympatric vertebrates such as marine mammals (Bergström, Haemig, & Olsen, 1999).…”