An extraordinary radiation of Hawaiian fancy-cased caterpillars (Lepidoptera: Cosmopterigidae: Hyposmocoma) with an emphasis on the purse-shaped cases

The spectacular Hawaiian moth genus Hyposmocoma includes 377 described species endemic to the Hawaiian archipelago. The total number of species may be greater than the radiation of Drosophila. Hyposmocoma has extraordinary life-histories and behavior, as some are known to be carnivorous, feeding on snails, while others are amphibious and can live under water. The genus is also unusual among Lepidoptera in that their larvae create protective “cases” in which they survive. An extraordinary morphological diversity of case types exist, which have tentatively been grouped into over ten different case morphotypes. The present study will examine the evolution of Hyposmocoma across the Hawaiian archipelago, and focus on the “purse case”, a group thought to be ancestral to other case types, such as the burrito and cone cases. Maximum likelihood and Bayesian molecular trees indicate that purse-cased Hyposmocoma evolved independently at least twice in the genus. Each purse-cased clade is monophyletic and strongly supported with high bootstrap values and posterior probabilities. We tentatively call these two monophyletic groups the “flat purse” and the “tubular purse” types, and postulate that the hard outer shell of purse cases allowed protection against parasitism and led to two independent radiations of purse cases.