Phylogeography and sister group of Lupangus, a new genus for three new flightless allopatric forest litter weevils endemic to the Eastern Arc Mountains, Tanzania (Coleoptera: Curculionidae, Molytinae)

Abstract

This paper reports discovery of a new genus <em>Lupangus</em> gen. n. with three new flightless weevils endemic to the forests of the Eastern Arc Mountains in Tanzania: <em>L. asterius</em> sp. n. (East Usambara; the type species), <em>L. jason</em> sp. n. (Uluguru) and<em> L. orpheus</em> sp. n. (Udzungwa). Maximum Likelihood phylogenetic analyses using parts of mitochondrial (COI), nuclear ribosomal (28S) genes, as well as the nuclear spacer region (ITS2) from 46 terminals grouped together the reciprocally monophyletic <em>Lupangus</em> (3 terminals) and <em>Typoderus</em> (3 terminals), with all three clades strongly supported. Phylogenetic analysis of 32 COI-5’ sequences recovered <em>Lupangus</em> species as reciprocally monophyletic, with <em>L</em>. <em>orpheus</em> being the sister to the rest. Internal phylogeny within both <em>L. jason</em> and <em>L.</em> <em>orpheus</em> are geographically structured, while that of <em>L. asterius</em> is not. Temporal analysis of <em>Lupangus</em> evolution using COI-5’ data assessed under slow and fast substitution rate schemes estimated separation of mitochondrial lineages leading to three <em>Lupangus</em> species at about 7–8 Ma and about 1.9–2.1 Ma, respectively. Temporal analyses consistently failed to suggest correlation between the timing of <em>Lupangus</em> evolution and the late Pleistocene climatic fluctuations, thus rejecting the hypothesis of faunal interchanges during the wettest periods of the last million years. Applicability of flightless weevils for dispersal-vicariance analysis is reviewed, and their mostly undocumented and taxonomically entangled diversity in the Tanzanian Eastern Arc Mountains is briefly highlighted.