Evolution of the elytral venation and structural adaptations in the oldest Palaeozoic beetles (Insecta: Coleoptera: Tshekardocoleidae)

The oldest definitive beetle, Coleopsis archaica gen. et sp. nov., is described from the earliest Permian (Asselian or early Sakmarian) of Germany (Grügelborn/Saarland). Its elytral venation is typical of the Early Permian Tshekardocoleidae. The elytral venation pattern of the type of Moravocoleus permianus Kukalová, 1969 is reconsidered in order to clarify structural peculiarities of the type genus of Moravocoleidae Kukalová-Peck & Beutel, 2011, herein regarded as a junior synonym of Tshekardocoleidae. The new discovery allows reinterpretation of the elytral venation, abdominal laterosternites, and other structures, making it possible to identify a ‘subelytral space’. Tshekardocoleoidea and Labradorocolidae are confirmed as Coleoptera, while Umenocoleidae sensu nov. and Umenocoleoidea are restored to Holometabola as a potential sister group of all Coleoptera. The holotype of Umenocoleus sinuatus Chen & T’an, 1973 needs to be revised in more detail. ‘Moravocoleus’ perditus Kukalová, 1969, regarded by Ponomarenko as a member of the genus Avocoleus, is excluded from Tshekardocoleidae and preliminarily considered as Archostemata incertae sedis. Oborocoleidae is considered as a taxon of more dubious position (order uncertain for Oborocoleus Kukalová, 1969, while Liberocoleus Kukalová, 1969 probably belongs to Archostemata (family uncertain)). Protocoleoptera and Paracoleoptera are considered as synonyms of Protelytroptera, while Archecoleoptera is dismissed as a paraphyletic group. Adiphlebia lacoana Scudder, 1885, previously proposed as the oldest beetle, is not a member of Coleoptera, as confirmed by Kukalová-Peck & Beutel (2012). The composition of beetle suborders and the origin of the order, which probably took place concurrently with the initial diversification of other holometabolan insects, are briefly discussed.http://zoobank.org/urn:lsid:zoobank.org:pub:2044EEFE-B88B-4552-B1F9-983E6F7A583D