Species of the genus Stigmaeus (Acariformes: Stigmaeidae) from the Karasu Valley (Türkiye): morphological examination and a taxonomic argument

In the present work, morphological characteristics of species of the genus Stigmaeus Koch collected from the Karasu Valley in the Munzur Mountains (Türkiye) were examined. A total of 11 species of the Stigmaeus were identified in this study. Among them, S. dokeri, S. maraghehiensis and S. purpurascens are recorded for the first time from Türkiye. The protonymph and deutonymph stages of S. bifurcus, as well as the larva, protonymph and deutonymph stages of S. dokeri, are described for the first time. Furthermore, morphological variations were observed for the first time in S. dokeri and S. pulumurensis. The names Stigmaeus africanus Soliman & Gomaa, 1986, S. banksi Gomaa & Hassan, 1986, S. triramus Soliman & Gomaa, 1986 and S. zaheri Gomaa & Hassan, 1986 are considered nomina nuda. This study also highlights the importance of maintaining the current concept of the genus Stigmaeus for taxonomic stability. While the available molecular data suggest that some species may form distinct clades, single-locus analyses based on limited data sets are not yet considered sufficient to justify clear divisions at the genus level. Therefore, it has been suggested that a more balanced approach would be to cautiously consider the idea of dividing Stigmaeus into separate genera and to restructure it based on subgenera or natural species groups, in accordance with the concept of Berlese (1910), and the aim is to open this systematic framework for discussion. In this context, the proposal to reinterpret certain taxa such as Ledermuelleriopsis Willmann and Villersia Kuznetsov not as independent genera but as subgenera within Eustigmaeus Berlese has also been opened for discussion within the scope of this unifying approach. In conclusion, this study contributes to the diversity of Stigmaeus in Türkiye with new records, documents different developmental stages and morphological variation, clarifies the nomenclatural status of some species-names, and advocates a taxonomic framework that prioritises subgeneric re-structuring over generic-level splitting within Stigmaeidae systematics.