Examining Species Boundaries and Evolutionary Relationships of New Zealand's Mite Harvesters in the Genus Rakaia (Arachnida; Opiliones; Pettalidae)

Mite harvesters (Suborder Cyphophthalmi, Order Opiliones) are small terrestrial arachnids that reside in leaf litter habitats and caves worldwide. Three genera of these animals are endemic to New Zealand, including Rakaia, the genus of focus in this study. Mite harvesters are a very interesting system for taxonomic study because they are incredibly dispersal-limited and morphologically conserved. This presents a unique challenge in terms of species classification that necessitates the application of an intensive integrative approach, a process which had not been fully completed for the genus Rakaia. In this study, I perform species delimitation analysis using an integrative approach in the hopes of further understanding the species structure within Rakaia. Based on this work, I present descriptions of two new species: R. n. sp. Kaikoura and R. n. sp. antipodiana clade 2 and validate existing species boundaries within Rakaia. This increased knowledge on a species level allows for further investigation of broader evolutionary relationships within Rakaia, specifically patterns of isolation-by-distance. An analysis of isolation by distance trends on a species level revealed that a widespread North Island species, R. media, has a weaker relationship between genetic distance and geographic distance than widespread South Island species, perhaps reflecting the impacts of Post-Pleistocene expansion. Overall, this study contributes to the larger goal of elucidating species relationships within Rakaia and engages with early analysis of broader evolutionary patterns and how they are impacted by geologic history.