Revisiting the morphology and systematic placement of the enigmatic cretaceous ommatid beetle bukhkalius lindae (Coleoptera: Archostemata: Ommatidae)

Abstract

The systematic position of Bukhkalius lindae (Jarzembowski et al. 2017) from mid-Cretaceous Burmese amber is revised based on a re-examination of the type specimen. Our observations confirm that B. lindae lacks unique apomorphies of Tetraphalerus Waterhouse, in which it was originally placed, including complete antennal grooves and mushroom-shaped micro-tubercles. It is well justified to place it into a separate genus, i.e., Bukhkalius Kirejtshuk & Jarzembowski, 2020. The incomplete but distinct antennal grooves and the Tetraphalerus-like mouthparts of B. lindae suggest that it has a close affinity to Tetraphalerus. Therefore, B. lindae may represent a missing link bridging the morphological gap between extant ommatid subfamilies Tetraphalerinae and Ommatinae.