The genus Pseudophoxinus Bleeker, 1860 is found in a wide range of habitats in central Anatolia, but it is not well known from a cytogenetic aspect. In this study the first karyotypic description of the spring minnows Pseudophoxinus crassus (Ladiges, 1960) and Pseudophoxinus hittitorum Freyhof & Özulug, 2010 by means of conventional methods (Giemsa staining, C-banding, silver nitrate impregnation (Ag-NORs)) was performed. Both species are endemic and have restricted distributions in Central Anatolia. Pseudophoxinus crassus and Pseudophoxinus hittitorum have the same diploid chromosome number, 2n = 50, patterns of distribution of constitutive heterochromatin (CH), and localization of nucleolus organizer regions (NORs), but differ in their karyotypic formulae (KFs). The C-banding technique revealed clear pericentromeric blocks of CH in many chromosomes; Ag-NORs treatment revealed consistent positive signals at the end of the short arms of a submetacentric chromosome pair, likely homologous in both species. The karyotypic differences found between these species can be used for their taxonomical study.

Salmonids are extremely important economically and scientifically; therefore, dynamic developments in their research have occurred and will continue occurring in the future. At the same time, their complex phylogeny and taxonomy are challenging for traditional approaches in research. Here, we first provide discoveries regarding the hitherto completely unknown cytogenetic characteristics of the Anatolian endemic flathead trout, Salmo platycephalus, and summarize the presently known, albeit highly complicated, situation in the genus Salmo. Secondly, by outlining future directions of salmonid cytogenomics, we have produced a prototypical virtual karyotype of Salmo trutta, the closest relative of S. platycephalus. This production is now possible thanks to the high-quality genome assembled to the chromosome level in S. trutta via soft-masking, including a direct labelling of repetitive sequences along the chromosome sequence. Repetitive sequences were crucial for traditional fish cytogenetics and hence should also be utilized in fish cytogenomics. As such virtual karyotypes become increasingly available in the very near future, it is necessary to integrate both present and future approaches to maximize their respective benefits. Finally, we show how the presumably repetitive sequences in salmonids can change the understanding of the overall relationship between genome size and G+C content, creating another outstanding question in salmonid cytogenomics waiting to be resolved.

This study was carried out on the chromosomal features of two populations (Kızılırmak and Sakarya Rivers) belonging to Luciobarbus escherichii (Steindachner, 1897). Metaphase chromosomes were obtained from kidney cells. The diploid chromosome number was 2n=100, consisting of 7 pairs of metacentric, 22 pairs of submetacentric and 21 pairs of subteloacrocentric chromosomes. The arm number (NF) was 158. Constitutive heterochromatin regions with C-banding were determined on the centromeres of chromosomes. NOR was observed on the short arms of 2 pairs of submetacentric chromosomes. This study is a contribution to cytogenetics of Anatolian cyprinids.

Diploid chromosome number, chromosome morphologies and chromosomal band properties (with C-banding and Ag-NOR staining) of endemic Oxynoemacheilus atili Erk'akan, 2012 were revealed out from Beyşehir Lake Basin, Turkey. Metaphase chromosomes were obtained from kidney cells. Diploid chromosome number was found as 2n = 50 and chromosome morphologies were as follows: five pairs of metacentric, nine pairs of submetacentric and 11 pairs of subteloacrocentric chromosomes. Fundamental arm number was calculated as 78. Constitutive heterochromatin regions were determined on the centromeres of chromosomes. NORs were detected on one pair of chromosomes. The obtained results may contribute to nemacheilid chromosomal studies.