Determination of the biological diversity and infection dynamics of myxozoa (cnidaria) parasites infecting merluccius merluccius (linnaeus, 1758) in the sea of Marmara

The aim of this study was to determine the biological diversity and parasitological characteristics of Myxozoa fish parasites infecting Merluccius merluccius L., 1758 (European hake) distributed in the Sea of Marmara. For this purpose, 47 hake specimens were obtained from the eastern coasts of the Sea of Marmara, covering the offshore areas of Yalova and İzmit Bay, and subjected to parasitological examination. The initial examination revealed the presence of two different Myxozoa species in the gallbladders of 12 hake hosts. Based on myxospore morphology, morphometric measurements, and molecular phylogenetic analyses using 18S rDNA nucleotide sequences, one of these parasites was identified as Pseudalataspora vanderlingeni. The other Myxozoa species was always observed in mixed infections with the first species, and therefore, genetic data could not be obtained. However, its myxospore morphology indicated that it belonged to the genus Ceratomyxa. Furthermore, the myxospore morphology and morphometric measurements revealed that Ceratomyxa sp.-1 differed from all Ceratomyxa species previously reported from Turkish marine waters. The data also indicated that this species was distinct from all currently described Ceratomyxa species worldwide, suggesting it may represent a new species. Nevertheless, this assumption requires confirmation through molecular phylogenetic analyses. Parasitologically, Ceratomyxa sp.-1 exhibited an infection prevalence of 10.6% and a parasite intensity of 3+, while P. vanderlingeni showed an infection prevalence of 14.8% and a parasite intensity of 3+. In conclusion, this study provides the first record of Myxozoa fish parasites from M. merluccius L., 1758 in Türkiye. In addition, it reports the presence of a Ceratomyxa species in the Sea of Marmara that differs from all Ceratomyxa species previously reported from Turkish waters. Moreover, this study represents the first record of both the genus Pseudalataspora and the species P. vanderlingeni from Turkish marine waters.