Karyotypic diversity in the Gobiidae: A comparative analysis of two Atlantic species.

Gobies (family Gobiidae) rank among the most diverse of all marine fish families. Although the cytogenetics of these small, ubiquitous fish is still a young field, studies on Atlantic species, despite their limited number, have already revealed a remarkable level of karyotypic variation. This karyotype diversity has provided critical evidence for discovering new species, uncovering population structures, identifying sex chromosomes, and pinpointing major shifts in repetitive DNA. This study presents the first chromosomal characterization of two Atlantic goby species, Coryphopterus glaucofraenum (Gill, 1863) and Evorthodus lyricus (Girard, 1858), using classical cytogenetics and base-specific fluorochrome staining. Our analyses revealed a striking divergence in their karyotypes. Evorthodus lyricus exhibited a karyotype of 2n = 46 (FN = 92), whereas C. glaucofraenum presented 2n = 40 (FN = 42), indicating significant differences in both chromosome and fundamental number (FN). These cytogenetic patterns, combined with existing data for the family, reinforce the high karyotypic diversity within Gobiidae and suggest a relationship between speciation processes and chromosomal modifications in the diversification of this family.