Dung beetle tribal classification (Coleoptera: Scarabaeidae: Scarabaeinae): Progress, problems, and prospects

Abstract

The subfamily Scarabaeinae has been traditionally divided into tribes on the basis of morphological similarity between groups of genera or, even, dissimilarity shown by a single genus. Although various tribal units have been described over the past 220 years, they had been recently reduced to a maximum of only 12 through synonymies within some tribes. However, following the advent of morphological and molecular cladistic systematics, it is clear that there are many discrepancies between phylogeny and phenetic tribal classification. As a result the number of tribes has now been expanded to 20 by revalidating some tribes or describing new groupings although this revision is incomplete. Thus, this study provides a comprehensive review of the current status of dung beetle tribal classification with regards to validity in terms of monophyly versus polyphyly or paraphyly. We discuss the systematic position of tribes among Scarabaeinae and provide a summary of the generic and species structure for each tribe. Given the enduring polyphyly or paraphyly in several tribes, it is clear that further tribal units will need to be described or revalidated to resolve the discrepancies. Therefore, we discuss how to use multiple lines of evidence (molecular, morphological, biogeographical, and paleontological) to build the tree of life for dung beetles and consequently provide stability in the tribal classification of the lineage.