Biogeography and speciation of arthropods across the Tasman Sea: Craterostigmus tasmanianus (Chilopoda: Craterostigmomorpha: Craterostigmidae), Monoscutidae (Opiliones: Eupnoi; Phalangioidea), and Triaenonychidae (Opiliones: Laniatores)

The geological history of Oceania is ancient and complex, starting with the breakup of Gondwana about 80 mya. Biogeographers since Wallace have been hypothesizing about the origin of New Zealand's remarkable fauna, and questions about the possible submersion of the Zealandia plate during the Oligocene. Here I study three arthropod taxa distributed across the Tasman sea and test hypotheses about the population structure, species delimitation, phylogenetics, and the timing of divergence events: the relict Tasmanian endemic centipede Craterostigmus tasmanianus (Chilopoda: Craterostigmomorpha: Craterostigmidae), and the harvestman families Monoscutidae (Opiliones: Eupnoi: Phalangioidea) and Triaenonychidae (Opiliones: Laniatores) of New Zealand.;Using statistical measures of population structure based on mitochondrial molecular markers, I found little genetic variation (9.42% on average) within populations of Craterostigmus tasmanianus, with the remaining 90.58% between populations. I found no evident effect of genetic isolation by distance. Estimated population clusters broadly correlated with gene networks and geology, although there was no correlation between the borders of these clusters and genetic distance, nor other putative barriers.;The family Monoscutidae constitutes one of the most charismatic soil arthropods in New Zealand, and a striking example or sexual dimorphism and male dimorphism, with non-descript females but colorful males with exaggerated chelicerae. Using the General Mixed Yule Coalescent-based method, and phylogenetic trees under maximum likelihood and parsimony criteria, I inferred a limited number of species for the endemic genera Forsteropsalis and Pantopsalis. I corroborated the monophyly of all genera, although the deeper relationships remain uncertain.;With extensive sampling in New Zealand for Triaenonychidae, a harvestman family of Gondwanan distribution, along samples from the genus Nuncia from Chile, I tested the monophyly of the current interfamilial phylogenetic divisions. Results place Soerensenellinae as paraphyletic with respect to Triaenonychinae, and call for the division of the Chilean and New Zealand Nuncia into distinct genera. Monophyly of all New Zealand genera is confirmed, except for the trans-Pacific Nuncia, and Pristobunus, the latter suggesting a case of trans-Tasman distribution. Time of divergence estimates suggest a pre-Oligocene presence of the genera in New Zealand.;This work sets a firm foundation for three new model groups of organisms to test hypotheses about the possible submergence of New Zealand, New Zealand as cradle of diversity, and population structure across the Tasman Sea.