Revision of Mesozoic fossils of the helophorid lineage of the superfamily Hydrophiloidea (Coleoptera: Polyphaga)

Abstract: A revision of the Mesozoic fossils belonging to the helophorid lineage of the superfamily Hydrophiloidea is performed and an adapted classification is suggested based on the phylogenetic analysis combining modern and fossil taxa of the lineage. Three genera are revealed as basal extinct Mesozoic clades of the helophorid lineage: Hydrophilopsia Ponomarenko, 1987, Laetopsia gen. nov. (adult forms) and Cretotaenia Ponomarenko, 1977 (larval form). Mesosperchus Ponomarenko, 1977 stat. nov. is resurrected from synonymy with Zetemenos Bode, 1953 and established as a formal subgenus of Helophorus Fabricius, 1775 containing probable stem taxa of that genus. Mesohelophorus Ponomarenko, 1977, stat. nov., is downgraded to a subgenus of Helophorus. Two new species are described: Helophorus (Mesosperchus) inceptivus sp. nov. (Sharteg, Mongolia, late Jurassic) and H. (M.) yixianus sp. nov. (Yixian Formation, China, Jurassic-Cretaceous boundary). Mesohelophorus elongatus Ponomarenko, 1990, syn. nov., is synonymised with Mesosperchus tarsalis Ponomarenko, 1977. The latter species and Hydrophilopsia gracilis Prokin, Ren & Fikáček, 2010 are transferred to Helophorus (Mesosperchus), resulting in the following new combinations: Helophorus (Mesosperchus) tarsalis (Ponomarenko, 1977), comb. nov. and H. (M.) gracilis (Prokin, Ren & Fikáček, 2010), comb. nov. Mesohelophorus sibiricus Ponomarenko, 1977 is transferred to Helophorus (Mesohelophorus) and the resulting secondary homonymy with Helophorus sibiricus (Motschulsky, 1860) is removed by proposing a new substitute name Helophorus palaeosibiricus nom. nov. for the former taxon. Hydrophilopsia baissensis Ponomarenko, 1987, H. bontsaganica Prokin, 2009, H. hydraenoides Prokin, Ren & Fikáček, 2010, H. mongolica Ponomarenko, 1987 and H. shatrovskiyi Prokin, Ren & Fikáček, 2010 are transferred to Laetopsia gen. nov. The inclusion of the fossil taxa into the helophorid lineage of the Hydrophiloidea made the slight adaptation of the diagnosis of the genus Helophorus necessary. Six fossil species included previously into the genera Helophorus, Mesosperchus and Mesohelophorus are excluded from the helophorid lineage: Mesosperchus notatus Ponomarenko, 1977, and M. schultzi Ponomarenko, 1985 (both transferred to Polyphaga incertae sedis), Mesohelophorus mongolicus Ponomarenko, 1986 (transferred to Buprestoidea), Mesosperchus angulatus Ponomarenko, 1985 (confirmed as not belonging to the Hydrophiloidea), Tychon antiquum (Giebel, 1856) (confirmed as Coleoptera incertae sedis) and Helophoropsis brodiei (Giebel, 1856) (transferred to Coleoptera incertae sedis). The genus Zetemenos Bode, 1953 is transferred to Coleoptera incertae sedis based on the examination of its type species, Z. sexlineatus Bode, 1953.

Key words: Hydrophiloidea, helophorid lineage, Helophoridae, Helophorus, Buprestoidea, new genus, new species, fossil record, Mesozoic, Jurassic, Cretaceous, China, Germany, Mongolia, Russia, United Kingdom