Oncelytris esquamatus gen. et sp. nov. from mid-Cretaceous amber of northern Myanmar (Coleoptera: Lucanidae)

Abstract

Lucanidae, or stag beetles, represents a spectacular group of scarabaeoid beetles, with mandibles often remarkably enlarged in males (Mizunuma & Nagai 1994). The earliest fossil of Lucanidae was documented from the Middle-Late Jurassic Daohugou biota (Nikolajev et al. 2011). Recently three fossil genera have also been reported from the mid-Cretaceous Burmese amber (Cai et al. 2017;Qiu et al. 2017;Wu et al. 2022). Here we describe a new lucanid fossil, Oncelytris esquamatus Li & Cai gen. et sp. nov., from Burmese amber, which shares a similar protibial morphology with the extant tribe Ceratognathini. The tuberculate elytra of Oncelytris are unique within the family.Pronotal disc widest basally, slightly wider than elytra combined; surface simple; lateral sides smooth, subparallel in posterior half and converging anteriorly in anterior half; anterior angles slightly produced; posterior angles right-angled. Prosternum with median longitudinal carina; prosternal process narrow, with procoxae subcontiguous. elytra 1.6 times as long as combined width, nearly parallel-sided in anterior three-fifths; lateral sides serrulate (at least in posterior half); punctures on surface likely not forming distinct rows; distinct tubercles present in posterior half of elytral surface. Mesocoxal cavities likely narrowly separated. Posterior intercoxal process of metaventrite apically with two acute points. Metacoxae transverse, subcontiguous.Protibia with one large apical spur; outer protibial edge with one large apical spine, one large postmedial spine, one moderately enlarged premedial spine, and numerous equal-sized small tooth-like spines. Mesotibia with paired apical spurs. Tarsi 5-segmented. Pretarsal claws simple; empodium well developed and bisetose.Abdomen with five ventrites; ventrite 5 apically emarginate.