Septiventeridae, a new and ancestral fossil family of Scarabaeoidea (Insecta: Coleoptera) from the Late Jurassic to Early Cretaceous Yixian Formation

Abstract

Morphologically, Scarabaeoidea is one of the best-studied groups of beetles. However, the incomplete preservation of presently known fossils is a fundamental problem in the interpretation of extinct species of the superfamily. Wing venation has long been recognized as a valuable character system in taxonomic and phylogenetic analyses. However, to date hind wing features of scarab fossils have not been analysed using geometric morphometrics. A new genus and a new species, Septiventer quadridentatus gen. et sp. nov., is described and illustrated and assigned to a new scarabaeoid family Septiventeridae fam. nov., based on one well-preserved specimen from the Yixian Formation of Liaoning Province, China. The phylogenetic position of Septiventer is inferred based on 68 morphological characters using a cladistic approach. Additionally, based on a geometric morphometric analysis of the hind wing of Septiventer, the structural affinities of 161 scarabs and six outgroup species is analysed, using 261 wing landmarks. Septiventeridae is identified as the sister group of the remaining Scarabaeoidea, with Glaresidae and Trogidae as the next branches. Consequently, it is crucial for an understanding of the early diversification of the superfamily, and for the reconstruction of early evolutionary transformations in the group. Septiventeridae differs strongly from most ‘modern’ lineages in wing shape. However, the structural affinity of the hind wings of Septiventeridae, Glaresidae and Trogidae are robustly supported by the results from morphometrics. This fits well with the phylogenetic hypothesis based on the general character set and strongly suggests that this wing pattern is closest to the scarabaeoid groundplan. The morphological features suggest good flying abilities of Septiventer, that it might have been active during the daytime, processed soft food, and was less active in digging tunnels than extant, more specialized dung beetles.

http://zoobank.org/urn:lsid:zoobank.org:pub:B0076219-3F4C-4E3D-8054-7DA855E0D8A4

Keywords:

• Septiventeridae
• Septiventer
• phylogeny
• geometric morphometrics
• new family
• fossil

Acknowledgements

We gratefully acknowledge the assistance of Dr Frank-Thorsten Krell (Denver Museum of Nature and Science, USA) for discussion and helping with the phylogenetic analyses. Maxwell V. L. Barclay and Malcolm Kerley strongly supported the first author when he visited the Natural History Museum, London. Dr Si-Qin Ge and Huai-Jun Xue (Institute of Zoology, Chinese Academy of Sciences) gave us many valuable comments on the first version of the manuscript. Ke-Qing Song and Xiao-Yan Hu (Institute of Zoology, Chinese Academy of Sciences) helped us with the photography of hind wings. This research was supported by the National Basic Research Program of China (973 Program) (No. 2011CB302102, 2012CB821906), the National Natural Science Foundation of China (Nos. 30900144, 31071964 and 31010103913), and the Knowledge Innovation Program of Chinese Academy of Sciences (Nos. KSCX2-EW-G-4 and KSCX2-EW-Z-8).