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 observation confirms 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.

Cretaceous beetles of the Jinju Formation (Coleoptera): Archostemata

“…Extensive studies have been conducted on the Mesozoic archostematan fossils from Asia in the past decades, especially on those from Central Asia (Ponomarenko, 1964(Ponomarenko, , 1966(Ponomarenko, , 1969, Mongolia (Ponomarenko, 1994(Ponomarenko, , 1997, Northeast China (e.g., Tan & Ren, 2009;Jarzembowski et al, 2013aJarzembowski et al, , b, 2015Yan et al, 2014;Cai & Huang, 2017), and Burmese (Myanmar) amber (e.g., Yamamoto, 2017Yamamoto, , 2021Li et al, 2019Li et al, , 2020bLi et al, , 2021cLi et al, , 2021dTihelka et al, 2020b;Li & Cai, 2021;Song et al, 2022). Most archostematan fossils discovered from the Cretaceous Jinju Formation in Korea belong to the common and widespread genera (Brochocoleus, Omma, and Notocupes/Zygadenia).…”

New species of Paraodontomma from mid-Cretaceous Burmese amber with muscle tissue preservation (Coleoptera: Archostemata: Ommatidae)

“…Yamamoto (2017) ruled out a close relationship of the extinct genus to fossils with wide epipleural rims assigned to Tetraphalerus, based on the lack of characteristic antennal grooves in Paraodontomma. However, no antennal grooves have been validly observed in any of the Mesozoic "Tetraphalerus" fossils (Li et al, 2021), and many of them have been transferred into genus Allophalerus Kirejtshuk just recently (Kirejtshuk, 2020). The overall shape of some Allophalerus is also similar to Paraodontomma.…”

Revisiting the morphology of the Cretaceous ommatid beetle Clessidromma palmeri (Coleoptera: Archostemata: Ommatidae)

“…However, Tetraphalerus is unique in Ommatidae (and differs from Clessidromma) in having antennomeres 5-11 without setae and mushroom-shaped tubercles (Beutel et al, 2008). The separate mentum present in Tetraphalerus and related fossils (Li et al, 2021b) is also not observed in Clessidromma. Considering the high morphological diversity found in fossil Ommatidae, the similarity between Clessidromma and Tetraphalerus might be merely homoplasious.…”