From Patagonia to the Himalayans: Protoptiline caddisfly diversity across oceans and continents

Protoptilinae is the most diverse of 3 subfamilies belonging to the saddle-, or tortoise-case making caddisfly family Glossosomatidae. These minute sized caddisflies have a very disjunct distribution: 1 genus is known from the East Palaearctic, Nearctic, and Oriental regions; the remaining 10 genera occur mostly in the Neotropics, including the Caribbean, with 2 of these also occurring in the Nearctic. Protoptilinae is the only glossosomatid subfamily to occur in the Neotropics with regional endemism occurring in the Greater Antilles, southeastern Brazil, and the southern Andes. Several alternative hypotheses regarding the historical biogeography of protoptiline caddisflies have been proposed including possible North American, Asian, or ancient Gondwanan origins. However, such hypotheses are only speculative since there has never been a modern phylogenetic analysis of Protoptilinae. Based on a phylogeny from both morphological and molecular data, we investigated the biogeographic history of Protoptilinae using a relaxed molecular clock analysis calibrated with fossil data, independent geologic evidence, and Bayesian dispersal-vicariance analysis. Minimum age estimates indicate that early diversification of Protoptilinae most likely occurred well after the Mesozoic break-up of Gondwanaland. However, the timing of many lineage divergences correlates with geologic events that would have facilitated movement between continents. Additionally, the current distribution of Protoptilinae is probably the result of a combination of both dispersal and vicariance events.