Fossils in Hawaii? The importance of a sub-fossil assemblage for understanding the Hawaiian Blackburnia radiation (Coleoptera: Carabidae)

The Hawaiian Islands are home to over 5,000 described, indigenous insect species. Intense phylogenesis has resulted in species radiations that serve as models for evolutionary biology. The genus Blackburnia (Coleoptera: Carabidae) has been the subject of numerical cladistic analysis characterized by 1, inclusion of all known species, 2, comprehensive morphological character selection; and 3, a test for monophyly using multiple outgroups. Phylogenetic analysis of extant species can now be complemented via the characterization of a pre-Polynesian insect community recovered from Makauwahi Cave, south-coastal Kauai. This community included both subsequently extirpated and currently extant carabid beetle taxa. Inclusion of sub-fossil taxa in the cladistic analysis of Blackburnia improves phylogenetic resolution while leaving previous taxic relationships undisturbed. Phylogenetic placements of sub-fossil taxa are uniformly in accord with area relationships derived from items-of-error biogeographic analysis based on extant species. Presence of sub-fossils representing extant species in the Makauwahi Cave deposit allows an assessment of the changes to biotic distributions that have occurred during the history of Kauai’s human habitation.