Cretaceous Research 100 (2019) 126e133
Contents lists available at ScienceDirect
Cretaceous Research
journal homepage: www.elsevier.com/locate/CretRes
Short communication yCretohlezkus gen. nov. from Upper Cretaceous Burmese amber demonstrates ancient origins of suctorial mouthparts in Eucinetidae (Coleoptera: Scirtoidea)
Paweł Jałoszynski
Museum of Natural History, University of Wrocław, Sienkiewicza 21, 50-335 Wrocław, Poland article info abstract
Article history: Eucinetidae is a small beetle family comprising only ten extant genera. Five of them have unusually Received 14 January 2019 modified mouthparts with a strongly transformed labium, which shows features interpreted as adap- Received in revised form tations to suctorial feeding. Among the hyperdiverse Coleoptera, similar feeding adaptations are known 21 February 2019 only in several genera of Cerylonidae and Leiodidae. Fossils attributed to Eucinetidae or representing taxa Accepted in revised form 18 March 2019 presumably closely related to eucinetids are known from Lower Cretaceous of China and Upper Jurassic Available online 23 March 2019 of Mongolia, but none of them shows modified mouthparts. The first fossil of a ‘suctorial eucinetid’, yCretohlezkus alleni gen. et sp. nov., is reported in the present paper, based on a well-preserved specimen Keywords: y Fossil in Cenomanian Burmese amber. A preliminary phylogenetic analysis placed Cretohlezkus near base of ‘ ’ Beetle the monophyletic suctorial eucinetid lineage, but branch support was too low to present a robust Myanmar evolutionary hypothesis. The prementum of yCretohlezkus is modified as strongly as that of extant Cenomanian members of this group, demonstrating early origins of still only speculative feeding habits of the ‘suc- torial eucinetids’, which presumably use Myxomycetes or Basidiomycetes as the source of food. © 2019 Elsevier Ltd. All rights reserved.
1. Introduction The scirtoid family Eucinetidae is a small group that comprises less than 50 extant species classified in the extant genera Bisaya The huge order of Coleoptera or beetles is characterized by Reitter, 1884, Eucilodes Vít, 1985, Eucinetella Nikitsky, 1996, Euci- biting mouthparts, and exceptions from the groundplan are not netus Germar, 1818, Euscaphurus Casey, 1885, Jentozkus Vít, 1977, very common. However, some highly specialized modifications are Noteucinetus Bullians & Leschen, 2004, Nycteus Latreille, 1829, known, most notably a suctorial feeding apparatus, which has Proeuzkus Vít, 2000, and Tohlezkus Vít, 1977 (Leschen, 2016, and independently evolved in phylogenetically distant groups, as Myr- later additions). They can be readily distinguished by a fusiform micholeva Lea, 1910 (Staphylinoidea: Leiodidae), several genera of body form and large metacoxal plates that cover most of the met- Cerylonidae (Cucujoidea), e.g., Cautomus Sharp, 1885 and Rostror- aventrite (Leschen, 2016). Eucinetids are cryptic beetles, usually ylon Slipinski, 1991 (Cerylonidae), and several genera of scirtoid collected by sifting leaf litter, under bark of trees or in rotten wood; Eucinetidae (Leschen, 2016). Interestingly, even though these some species have been found in association with Myxomycetes or modifications are unusual and highly interesting, their morphology Basidiomycetes, on which the adults and larvae supposedly feed remains exceptionally poorly characterized, and almost nothing is (Leschen, 2016). Adults of some species can also be collected by known about actual function of structures that form the piercing- pitfall traps in sandy and relatively dry xerothermous habitats sucking apparatus. Even the source of food for these beetles has (Jałoszynski, pers. obs.). not been confirmed yet (e.g., Newton, 2016), and the question when The most unusual feature of eucinetid beetles is a high pro- such adaptations have originated remains open. portion of taxa with strongly modified adult mouthparts, with the anterior portion of the labium (i.e., the prementum) strongly elongate, subtriangular, and presumably functioning as a piercing device. Leiodidae with ~380 genera (Newton, 2016) have only one Abbreviations: cPJ, collection of Paweł Jałoszynski, Wrocław, Poland; MNHW, genus with piercing-sucking mouthparts, and among 52 genera of Museum of Natural History, University of Wrocław, Wrocław, Poland. Cerylonidae there are only six genera with a strongly elongate, E-mail address: [email protected]. https://doi.org/10.1016/j.cretres.2019.03.016 0195-6671/© 2019 Elsevier Ltd. All rights reserved. P. Jałoszynski / Cretaceous Research 100 (2019) 126e133 127