Cryptic species, biogeographic complexity and the evolutionary history of theEctemnorhinusgroup in the sub-Antarctic, including a description ofBothrometopus huntleyi, n. sp.

Abstract

AbstractThe biogeography of the South Indian Ocean Province (SIP) biotas has long been controversial. Much of the discussion has been based on interpretation of species distributions, based on morphological or anatomical delimitations. However, molecular phylogenetic approaches elsewhere have recently shown that interpretations based solely on morphological data may be misleading. Nonetheless, few studies have employed molecular phylogenetic approaches to understand the biogeography of the SIP biotas. We do so here for theEctemnorhinusgroup of genera, a monophyletic unit of weevils endemic to the region. We use mitochondrial cytochrome oxidase I DNA sequence data to reconstruct relationships among 13 species and 22 populations in the generaPalirhoeus,BothrometopusandEctemnorhinus. On the basis of this analysis we find little support for separating the genusPalirhoeusfromBothrometopus, and little support for the morphologically-based species groups currently recognized withinBothrometopus. Using a molecular clock we show that dispersal among islands probably took place against the prevailing wind direction. These data also support a previous hypothesis of radiation of the epilithic generaBothrometopusandPalirhoeusduring the Pliocene/early Pleistocene, but reject the hypothesis that the genusEctemnorhinusradiated following the last glacial maximum. We show thatBothrometopus parvulus(C.O. Waterhouse) on the Prince Edward Islands comprises two species that are not sister taxa. We name the second speciesBothrometopus huntleyin. sp. and provide a description thereof.