An integrative taxonomic and phylogenetic approach reveals a new genus of Australasian Cycas-pollinating weevils (Coleoptera: Curculionidae: Cossoninae)

Abstract

Cycas is the second-largest genus of cycads in Australia and the sole cycad genus in Papua New Guinea. In contrast to the other Australian cycads, which are mainly pollinated by weevils of the Tranes group of Molytinae, the Australian Cycas species are pollinated by tiny weevils belonging to the subfamily Cossoninae but representing an unnamed genus. This study evaluates the taxonomic status of these weevils by combining morphological examination with molecular phylogenetic analyses and species delineation based on mitochondrial DNA. The results reveal that the Cycas-pollinating weevils in Australia comprise only one species, here described as Zimmiodes australis gen. et sp. nov., with another species in Papua New Guinea, described as Zimmiodes papuanus sp. nov. The phylogenetic analyses and morphological comparison reveal that Zimmiodes belongs in the tribe Pentarthrini of Cossoninae and that the related Tychiodes group includes not only Tychiodes Wollaston, Tychiosoma Wollaston and Nanoplaxes Heller but also Tyrpetes Heller and is also assignable to Pentarthrini. The conspecificity of Zimmiodes weevils from all Australian Cycas species sampled suggests the likely taxonomic oversplitting of the Australian Cycas species and thus provides new insights into the taxonomy of the Australian cycads.