ntegrative morphological and molecular assessment of Mediterranean dragonets (Callionymidae) from Anatolian coasts

The family Callionymidae comprises a taxonomically challenging group of benthic marine fishes, mainly due to pronounced sexual dimorphism, ontogenetic variation, and the limited reliability of some diagnostic morphological characters. In the present study, six dragonet species occurring along the Turkish coasts, Callionymus filamentosus, C. lyra, C. pusillus, C. risso, Synchiropus phaeton, and S. sechellensis, were examined using morphological and molecular approaches. Specimens were collected from the Black Sea, Sea of Marmara, Aegean Sea, and Levantine Basin. Morphometric and meristic characters, coloration patterns, sexual dimorphism, and preopercular spine morphology were evaluated. In order to complete morphological identification and provide an independent molecular assessment of species differentiation, mitochondrial COI sequences were analysed using DNA barcoding and phylogenetic approaches. A Principal Component Analysis (PCA) based on 14 morphometric ratios from all 35 individual specimens was used to evaluate morphological variation among the examined taxa. The first two principal components accounted for 55.0% of the total variation, with the two Synchiropus species showing comparatively distinct distributions in morphometric space, whereas greater overlap was observed among the four Callionymus species. COI sequences were obtained from 22 individuals. Intraspecific genetic divergence ranged from 0 to 1.1%, whereas interspecific distances ranged from 11.9% to 24.7%. Maximum Likelihood analysis recovered distinct clusters corresponding to the morphologically identified species, while the position of C. filamentosus sequences indicated that phylogenetic relationships within the examined callionymids warrant further investigation. Overall, the combined morphological and molecular results support the complementary use of traditional diagnostic characters and DNA barcoding for the identification of Mediterranean dragonets. The present study also contributes additional COI barcode data for poorly represented Mediterranean Callionymidae and provides baseline information for future systematic and phylogenetic studies.