A transcriptome-based phylogeny of Scarabaeoidea confirms the sister group relationship of dung beetles and phytophagous pleurostict scarabs (Coleoptera)

Abstract

Scarab beetles (Scarabaeidae) are a diverse and ecologically important group of angiosperm-associated insects. As conventionally understood, scarab beetles comprise two major lineages: dung beetles and the phytophagous Pleurosticti. However, previous phylogenetic analyses have not been able to convincingly answer the question whether or not the two lineages form a monophyletic group. Here we report our results from phylogenetic analyses of more than 4,000 genes mined from transcriptomes of more than 50 species of Scarabaeidae and other Scarabaeoidea. Our results provide convincing support for the monophyly of Scarabaeidae, confirming the debated sister group relationship of dung beetles and phytophagous pleurostict scarabs. Supermatrix-based maximum likelihood and multispecies coalescent phylogenetic analyses strongly imply the subfamily Melolonthinae as currently understood being paraphyletic. We consequently suggest various changes in the systematics of Melolonthinae: Sericinae Kirby, 1837 stat. rest. and sensu n. to include the tribes Sericini, Ablaberini and Diphucephalini, and Sericoidinae Erichson, 1847 stat. rest. and sensu n. to include the tribes Automoliini, Heteronychini, Liparetrini, Maechidiini, Scitalini, Sericoidini, and Phyllotocini. Both subfamilies appear to consistently form a monophyletic sister group to all remaining subfamilies so far included within pleurostict scarabs except Orphninae. Our results represent a major step towards understanding the diversification history of one of the largest angiosperm-associated radiations of beetles.

Contrasting results of multiple species delimitation approaches cause uncertainty in synecological studies: A case study on Sri Lankan chafers

“…Thirty‐three morphospecies (or 12 haplotypes out of 332) were represented from more than one locality, but no one was found in more than half of all localities. The resulting maximum likelihood tree (Figure 1) showed general agreement with subfamily and genus level classification (Ahrens et al, 2014; Dietz, Seidel, et al, 2023; McKenna et al, 2019). Monophyletic clades resulted for all tribes (Diplotaxini, Sericini, Rhizotrogini and Leucopholini) and most subfamilies (Rutelinae and Dynastinae), the latter two formed a monophyletic sister clade.…”

Evidence for the independent evolution of a rectal complex within the beetle superfamily Scarabaeoidea

“…A putative evolutionary distribution of rectal complexes is shown in Figure 1. Note that a more recent phylogeny based on transcriptomic data gave somewhat different relationships, for example placing Glaphyridae in a more basal position (Dietz et al, 2023). The current picture is complex, and may be explained by multiple gains and/or losses of rectal complexes in Scarabaeoidea, although the limited sampling and variable quality of previous reporting adds to the uncertainty.…”