Abstract:
The 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 the Ectemnorhinus group 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 genera Palirhoeus, Bothrometopus and Ectemnorhinus. On the basis of this analysis
we find little support for separating the genus Palirhoeus from Bothrometopus, and little support for the
morphologically-based species groups currently recognized within Bothrometopus. 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 genera Bothrometopus and Palirhoeus during
the Pliocene/early Pleistocene, but reject the hypothesis that the genus Ectemnorhinus radiated following
the last glacial maximum. We show that Bothrometopus parvulus (C.O. Waterhouse) on the Prince Edward
Islands comprises two species that are not sister taxa.We name the second species Bothrometopus huntleyi n. sp.
and provide a description thereof.
