Tshekardocoleidae Explained

Tshekardocoleidae is an extinct family of stem group beetles, known from the Permian. They represent some of the earliest known beetles. They first appeared during the Cisuralian, before becoming extinct at the beginning of the Guadalupian.^[1] A claimed Jurassic record is doubtful.^[2] Like other primitive beetles, they are thought to have been xylophagous.^[1] The oldest known beetle, Coleopsis, was originally assigned to this family, but is now assigned to its own family Coleopsidae.

The Tshekardocoleidae are thought to have retained several plesiomorphies (ancestral characters) of Coleoptera in a broad sense. For instance, their elytra are flattened, lack epipleura (outer margins), cover the body loosely, and their tips extend beyond the apex of the abdomen. Their abdomens have a nearly cylindrical shape and are thought to have been flexible, apparently being able to strongly contract and expand. In extant beetles, the elytra are tight-fitting, forming a subelytral space which is absent in Tshekardocoleidae.^[3]

Taxonomy

thumb|right|upright|undescribed Tshekardocoleid larvae, Tshekarda siteKirejtshuk (2020) included the following genera in Tshekardocoleidae^[2]

• †Avocoleus – Obora site (Permian Sakmarian); Moravia, Czech Republic
  • †Avocoleus fractus (Type species)
  • †Avocoleus neglegens
• †Boscoleus – Obora site (Permian Sakmarian); Moravia, Czech Republic
  • †Boscoleus blandus (Type species)
• †Eocoleus – Obora site (Permian Sakmarian); Moravia, Czech Republic
  • †Eocoleus scaber (Type species)
• †Moravocoleus – Obora site (Permian Sakmarian); Moravia, Czech Republic
  • †Moravocoleus permianus (Type species)
• †Permocoleus – Midco Member (Permian, Artinskian); Noble County, Oklahoma, USA
  • †Permocoleus wellingtoniensis (Type species)
• †Prosperocoleus – Obora site (Permian Sakmarian); Moravia, Czech Republic
  • †Prosperocoleus prosperus (Type species)
• †Retelytron – Obora site (Permian Sakmarian); Moravia, Czech Republic
  • †Retelytron conopeum (Type species)
• †Sylvacoleodes – Tshekarda site (Permian Kungurian); Suksun, Perm Krai, Russia
  • †Sylvacoleodes admirandus (Type species)
• †Sylvacoleus – Tshekarda site (Permian Kungurian); Suksun, Perm Krai, Russia
  • †Sylvacoleus richteri (Type species)
  • †Sylvacoleus sharovi
• †Tshekardocoleus – Tshekarda site (Permian Kungurian); Suksun, Perm Krai, Russia
  • †Tshekardocoleus magnus (Type species)
  • †Tshekardocoleus minor
• †Umoricoleus – Obora site (Permian Sakmarian); Moravia, Czech Republic
  • †Umoricoleus perplex (Type species)
• †Votocoleus – Obora site (Permian Sakmarian); Moravia, Czech Republic
  • †Votocoleus submissus (Type species)

The genus Uralocoleus had been placed in the family by some authors, but the type species Uralocoleus splendens was considered incertae sedis by Kirejtshuk (2020) as a possible beetle or cockroach. The second species placed in the genus "Uralocoleus" ultimus was rejected from placement in Uralocoleus and listed as "genus incertus" ultimus .^[2] The genus Dictyocoleus, described from the Jurassic and containing only the type species Dictyocoleus jurassicus, was originally placed in the family but was excluded by Kirejtshuk (2020).^[2]

Notes and References

1. Zhao. Xianye. Yu. Yilun. Clapham. Matthew E. Yan. Evgeny. Chen. Jun. Jarzembowski. Edmund A. Zhao. Xiangdong. Wang. Bo. 2021-11-08. Perry. George H. Fikacek. Martin. Early evolution of beetles regulated by the end-Permian deforestation. eLife. 10. e72692. 10.7554/eLife.72692. 2050-084X. free. 34747694 . 8585485.
2. Kirejtshuk . Alexander G. . 2020-02-17 . Taxonomic Review of Fossil Coleopterous Families (Insecta, Coleoptera). Suborder Archostemata: Superfamilies Coleopseoidea and Cupedoidea . Geosciences . 10 . 2 . 73 . 2020Geosc..10...73K . 10.3390/geosciences10020073 . 2076-3263 . free.
3. Boudinot . Brendon Elias . Yan . Evgeny Viktorovich . Prokop . Jakub . Luo . Xiao-Zhu . Beutel . Rolf Georg . 2022-07-28 . Permian parallelisms: Reanalysis of †Tshekardocoleidae sheds light on the earliest evolution of the Coleoptera . Systematic Entomology . 48 . en . 69–96 . 10.1111/syen.12562 . 251171914 . 0307-6970. free .