Comparative cytogenetics of three endemic gudgeons of Gobio Cuvier, 1816 (Ostariophysi: Cypriniformes: Gobionidae)

Karyotypes and chromosomal banding characteristics of Gobio fahrettini Turan, Kaya, Baycelebi, Aksu & Bektas, 2018, Gobio gymnostethus Ladiges, 1960 and Gobio insuyanus Ladiges, 1960, from Anatolia, Turkey, were examined using conventional cytogenetic techniques (Giemsa, C-banding and Ag-NOR). The species studied had invariably diploid chromosome number 2n = 50 and karyotype composed of one uniarmed and 24 biarmed chromosomes. The largest chromosome pair in the karyotypes was a submetacentric pair. C-positive heterochromatin located on the pericentromeres of most of the chromosomes. Also, heterochromatic blocks were located on two chromosome pairs in G. gymnostethus whereas in one chromosome pair in G. fahrettini. The nucleolus organizer regions were located terminally on the p arms of one submetacentric chromosome pair in all three species. Morphologically differentiated sex chromosomes were not detected. This study is the first chromosomal study of three endemic Gobio species from Anatolia.

Automated summary

This study examined the karyotypes and chromosomal banding characteristics of three endemic Gobio species from Anatolia, Turkey, revealing that all species had a diploid chromosome number of 2n = 50 and a karyotype composed of one uniarmed and 24 biarmed chromosomes. The C-positive heterochromatin was located on the pericentromeres of most chromosomes, with nucleolus organizer regions located terminally on the p arms of one submetacentric chromosome pair in all three species. No morphologically differentiated sex chromosomes were detected in the study.