The first larval record of Migadopinae (Coleoptera: Adephaga: Carabidae) from mid-Cretaceous Kachin amber, northern Myanmar

Abstract

A new genus and species of Carabidae (Coleoptera: Adephaga), Cretomigadops bidentatus gen. et sp. nov., is described based on a well-preserved specimen from mid-Cretaceous Kachin amber from northern Myanmar. It is a first instar shortly after hatching, with distinct, elongate frontal eggbursters and a disproportionally large head. Cretomigadops bidentatus gen. et sp. nov. displays typical adephagan features and is classified as a larva of Carabidae based on a strongly sinuate frontal suture. It is assigned to Migadopinae based on characters of the head, especially the presence of two acute subapical mandibular teeth. It differs from other known genera of this small subantarctic subfamily by its long urogomphus, elongate legs with equal pretarsal claws and a long abdominal segment X. It is the first definite Mesozoic larval record of Carabidae from amber. Differences between C. bidentatus gen. et sp. nov. and four other fossil caraboid larvae are also discussed. The mandibles with a falcate apical tooth and two additional sharp subapical teeth indicate that C. bidentatus gen. et sp. nov. was a specialized active predator and good at grasping and piercing small arthropods. The elongate and articulated urogomphi, the long legs, the well-developed stemmata and the pigmented cuticle indicate that the larva was a surface runner, moving mostly on the soil surface and hunting more or less fast-moving prey. In contrast to the subantarctic distribution of Migadopinae, C. bidentatus gen. et sp. nov. preserved in Burmite shows that the distribution range of the subfamily was wider in the Mesozoic.