NOR and C-heterochromatin characteristics of Ellobius lutescens Thomas, 1897 (Rodentia, Cricetidae) from Turkey

The genus Ellobius Fischer, 1814, adapted to subterranean life, consists of five species distributed in the Palaearctic region and only Ellobius lutescens Thomas, 1897 occurs in Turkey. Although karyological, morphological, and biological studies have been conducted on populations of this species in Turkey, there is no study focused on nucleolar organizer regions (NORs) or C-heterochromatin characteristics. Nine specimens (five females and four males) were collected from four different localities in Van and Hakkâri provinces in Eastern Anatolia in this study. Cytogenetic analyses on these specimens confirmed a conserved diploid number (2n = 17) and the unusual sex chromosome system (XO in both sexes). An interstitial NOR on chromosome 1 and numerous telomeric NORs on the other chromosomes were detected by silver nitrate staining. In addition, C-banding analyses detected no C-band heterochromatin in any of the chromosomes, including the X. These cytogenetic results, along with current morphometric and genetic data, indicate subspecies-level variation between Turkish and Iranian populations, emphasizing the influence of physical barriers on micro-evolutionary divergence. This study is the first investigation of NORs and C-heterochromatin in Turkish populations of the subterranean rodent E. lutescens to date. In addition, our study expands the southernmost distribution limit of this species up to Karabey village (Yüksekova-Hakkâri) in Turkey.