Evolutionary dynamics of the chromosomal changes in the genus Cyphophthalmus (Arachnida: Opiliones) on the Balkan Peninsula

We investigated the genus Cyphophthalmus within the suborder Cyphophthalmi (Arachnida: Opiliones), focusing on its cytogenetic evolution in the Balkan Peninsula. Our comprehensive analysis of 21 species revealed a notable range in diploid chromosome numbers (2n = 24–30), challenging previous assumptions of genetic uniformity within this group. Using fluorescent in situ hybridization (FISH) with an 18S rDNA probe, we detected variability in the number of loci, with evidence of independent increases in this cluster (up to five pairs). This study combines the results of phylogenetic reconstruction based on analysis of mitochondrial gene cytochrome c oxidase subunit I (COI) (including karyotyped individuals) with standard and molecular cytogenetic techniques, making it the first of its kind in harvestman research. The findings reveal a significantly higher level of biodiversity in the Balkan Peninsula than previously recognized, suggesting complex differentiation within the genus Cyphophthalmus. Additionally, our results highlight the efficacy of cytogenetics as a tool for species’ delineation, enriching our understanding of the evolutionary history of the genus and emphasizing the intricate genetic diversity shaped by the unique geological and environmental history of the Balkan Peninsula.