Specialised subcortical cylindrical bark beetles from mid-Cretaceous Burmese amber (Coleoptera: Zopheridae: Colydiinae)

ABSTRACT

Cylindrical bark beetles (subfamily Colydiinae) are a group of mycophagous and predatory beetles placed in the family Zopheridae with a complicated taxonomic history and an unresolved phylogeny. We describe a new genus and two new species of strikingly cylindrical and elongate colydiid beetles from mid-Cretaceous Burmese amber mined in northern Myanmar (ca 99 Ma). Bifurderum minutum gen. et sp. nov. and B. donoghuei gen. et sp. nov. show a puzzling combination of characters including antennal and mandibular insertions concealed dorsally, 11-segmented antennae with a loose 2-segmented club, apical antennal segment not enclosed in the preceding antennomere, open procoxal cavities, prosternal process as wide as the maximum diameter of the procoxae and not expanding apically to close the procoxal cavities, narrowly separated metacoxae, and tarsi simple. The unusual body form of Bifurderum gen. nov. points towards a predatory life inside the galleries of wood-boring insects. The new fossils substantially expand the known range of morphological disparity in Mesozoic colydiid beetles and suggest that adaptation for life in the galleries of xylophagous insects in cylindrical bark beetles evolved by the mid-Cretaceous.

KEYWORDS:

• Colydiinae
• ironclad beetles
• Synchitini
• fossil
• Mesozoic
• Myanmar
• palaeodiversity

Acknowledgments

We thank two anonymous reviewers for their valuable comments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences [XDB26000000 and XDB18000000]; the National Natural Science Foundation of China [41688103 and 41672011]; and the Second Tibetan Plateau Scientific Expedition and Research [2019QZKK0706].