Abstract
The fossil beds of the Karabastau Formation in southern Kazakhstan, known as the "Jurassic Lake of Karatau", represent one of the richest Lagerstätten for Jurassic insects, with more than 800 described species. This year marks the centenary of the first fossil insect descriptions from Karatau, published by A.V. Martynov in 1925. Among the most prominent insect groups from this locality are the Anaxyelidae, a relict family of siricoid woodwasps. Here we report the first occurrence of the subfamily Syntexinae in Karatau, based on a newly discovered and described genus and species, Karasyntexis martynovi gen. et sp. nov., from the Galkino locality. This is only the second Jurassic record of Syntexinae globally. We provide a detailed morphological description of the new taxon and compare it with related syntexine genera. In addition, we reassess the current state of the four historically known fossiliferous localities of the Karabastau Formation (Galkino, Mikhailovka, Karabastau, and Chugurchak), all of which were revisited during a 2025 field expedition. A total of 22 anaxyelid species are now known from Karatau, highlighting the site's exceptional paleodiversity. Our findings suggest that the true diversity of Karatau's anaxyelids remains significantly underexplored and underscore the importance of renewed paleontological research in this classic locality.