Dryophthorinae weevils (Coleoptera: Curculionidae) of the forest floor in Southeast Asia: Three-marker analysis reveals monophyly of Asian Stromboscerini and new identity of rediscovered Tasactes

摘要

The nominal genus Tasactes Faust, 1894, consisting of two originally included nominal species from Myanmar, is rediscovered for the first time since being erected. Adult weevils herein assigned to the taxonomically re-defined Tasactes were abundant in forest floor litter at five localities in China (Yunnan and Sichuan), plus one specimen is available from Shaanxi and three from Nepal. Phylogenetic analysis of a 2,275 bp matrix concatenated from one mitochondrial (COI) and two nuclear markers (ITS2 and 28S) revealed that the monophyletic Tasactes consists of eight evolutionary significant terminal clades, either allopatric (three) or sympatric (two on Cang Shan in Yunnan and three on Mount Emei in Sichuan). The genus Tasactes is nested within the monophyletic Stromboscerini, while the tribe is sister to monophyletic Dryophthorus . The two morphological diagnostic characters of Tasactes, which are unique within the tribe, are the transversely truncated antennal club and conically projecting velvety apex of the club. So defined, Tasactes renders the genus Orthosinus paraphyletic. Considering the taxonomic neglect and uncertainties surrounding nominal Stromboscerini, all herein reported members of this tribe, including the Tasactes , are not assigned to Linnaean species. This paper illustrates the "clogging taxonomy" phenomenon, in which obscure historical names render taxonomic assignment of newly sampled specimens precarious. All the data used herein (localities, sequences, specimen images) are available online in public datasets dx.doi.org/10.5883/DS-TASACT1 and dx.doi.org/10.5883/DS-TASACT2.