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)

摘要

This paper reports discovery of a new genus Lupangus gen. n. with three new flightless weevils endemic to the forests of the Eastern Arc Mountains in Tanzania: L. asterius sp. n. (East Usambara; the type species), L. jason sp. n. (Uluguru) and L. orpheus 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 Lupangus (3 terminals) and Typoderus (3 terminals), with all three clades strongly supported. Phylogenetic analysis of 32 COI-5’ sequences recovered Lupangus species as reciprocally monophyletic, with L . orpheus being the sister to the rest. Internal phylogeny within both L. jason and L. orpheus are geographically structured, while that of L. asterius is not. Temporal analysis of Lupangus evolution using COI-5’ data assessed under slow and fast substitution rate schemes estimated separation of mitochondrial lineages leading to three Lupangus 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 Lupangus 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.