Molecular systematic analysis of nihoa Hyposmocoma reveals cryptic diversity

Despite their ability to colonize and speciate across the current high islands, few Hawaiian endemic lineages trace their origin up the archipelago to islands that rose before the emergence of Kauai approximately 5 million years ago (m.y.a). The moth genus Hyposmocoma is an exception, with many of its more than 400 described species restricted to diminishing peaks and atolls of the Northwest Hawaiian Islands (NWHI). Previous work has dated the origin of the genus to more than 15 m.y.a, with ancestral species dispersing down the island chain in accordance with the progression rule as volcanic activity generated new islands. Molecular data for a series of recently collected Hyposmocoma from the NWHI of Nihoa is combined with the pre-existing dataset to assess how these new collections fit into the broader phylogeny of the genus. Phylogenies were generated using a total of 3993 nucleotide characters from one mitochondrial gene (cytochrome oxidase I) and four nuclear genes (elongation factor 1α, carbomoylphosphate synthase, ribosomal protein S5 and cytosolic malate dehydrogenase) for 101 individuals from at least 95 taxa. These phylogenies reinforced monophyly by case type among all individuals, including those from Nihoa, and revealed an undescribed species of Nihoa cone-case. Furthermore, they supported unexpected placement of Nihoa burrito-cases with regards to the main islands.  These results have implications regarding the evolutionary history of Hyposmocoma diversity on Nihoa. Deviations from expected biogeographic patterns call for collection efforts to bridge anomalous evolutionary gaps to clarify dispersal patterns across the archipelago.