Morphology of male genitalia and legs reveals the classification of Mesozoic Zoraptera (Insecta)

Zoraptera is a small insect order with less than 50 described species from mostly tropical and subtropical regions of the World. The current system of extant Zoraptera is based on the results of molecular phylogeny combined with the morphology of male genitalia, and supplemented by the characters on the male abdomen and a number of metatibial spurs. However, fossil representatives of Zoraptera have not yet been classified into the modern system and most of them remained in the collecting genus Zorotypus Silvestri, 1913, because the genitalia were not observable or examined in detail. In this study, for the first time, we describe and critically evaluate the male genitalia and other principal diagnostic characters of all available Mesozoic Zoraptera. Our results lead to the first proposal of the generic classification of Mesozoic Zoraptera. We describe two new genera, Cretozoros gen. nov. and Burmazoros gen. nov., reinstate Paleospinosus Kaddumi, 2005, stat. restit. from synonymy with the subgenus Octozoros Engel, 2003 (in Zorotypus), and elevate Octozoros Engel, 2003 to a genus level. Cretozoros gen. nov., Paleospinosus stat. restit. and Octozoros stat. nov. are classified in Spiralizoridae: Latinozorinae, while Burmazoros gen. nov. and Xenoburmiticus Engel & Grimaldi, 2002 are classified in Zorotypidae: Zorotypinae. Altogether, it was possible to classify nine out of the 11 currently recognized species of Mesozoic Zoraptera. Zorotypus hukawngi Chen & Su 2019 is synonymized with Cretozoros acanthothorax (Engel & Grimaldi, 2002), comb. nov. and Zorotypus hirsutus Mashimo, 2018 is synonymized with Octozoros robustus (Liu, Zhang, Cai & Li, 2018), stat. restit., comb. nov., which is simultaneously restituted from the synonymy with Octozoros cenomanianus (Yin, Cai & Huang, 2018), comb. nov. The classification of Mesozoic Zoraptera into the modern system enables us to better understand the diversity of their internal lineages during the early evolution of this enigmatic insect order.