A preliminary molecular phylogeny of the Namib Desert darkling beetles (Tenebrionidae)

Abstract

A systematic classification of Namib Desert darkling beetles (Coleoptera: Tenebrionidae) based on morphological characters is complicated as strong selection pressures exerted by desert conditions have led to a suite of convergent morphological characteristics. Here we present a first and preliminary insight into the relationships within the tribes Zophosini, Eurychorini and Adesmiini using molecular methods. We analysed partial sequences of the mitochondrial genes cytochrome oxidase II and cytochrome b of 16 individuals comprising 12 species. Minimum Evolution, Maximum Parsimony, Maximum Likelihood and Bayesian inference were applied for analysing sequence data. The genus Pimelia was used as outgroup and for calibrating divergence time estimates. Overall, results supported phylogenies constructed on morphological characters. The proposed monophyly of the artificially defined tribe Zophosini did receive sufficient support. Speciation events in Namibian darkling beetles likely occurred during periods of aridification about 35 Mya, 16 Mya and 5–10 Mya. Those periods could be related to geological events and climate change due to the glaciation of Antarctica and the development of the Benguela current.