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Honors Project On-Campus Access Only

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Advisor: Dr. Sarah L. Boyer

Abstract

Neopurcellia is a monotypic genus of harvestmen endemic to New Zealand. These dispersal-limited organisms have a paradoxically widespread distribution across the West coast of the South Island, perhaps suggestive of multiple cryptic species within the lineage. Most morphological diagnostic characters of mite harvestmen are found on the ventral side of the body; therefore, little attention is typically given to dorsal morphology. This research analyzes the phylogeography of the genus, estimates its divergence and diversification dates, and describes a surprising level of within-species morphological variation in their dorsal anatomy not yet described in literature. We reconstructed the phylogeographic relationships between Neopurcellia salmoni populations using DNA sequence data from the fast-evolving mitochondrial locus COI and estimated divergence dates using BEAST. Phylogenetic analyses revealed two distinct and well- supported clades occupying distinct geographical regions without any overlap, with monophyletic groups of populations corresponding to similar or adjacent geographic regions. Dating estimates placed Neopurcellia divergence at 163 Ma and diversification events starting 80 Ma. SEM imaging of the dorsal anatomy revealed larger granules and pores on the sulci between different tergites for some but not all of the male specimens, serving as clear example of male dimorphism. There was not a significant geographic or phylogenetic signal apparent in the distribution of dorsal pores and larger granules, and they are hypothesized to have evolved as part of an alternative reproductive tactic. The presence of two male morphotypes in N. salmoni serves as evidence for the first case of male dimorphism observed in Cyphophthalmi.

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