Prior to this study, only three ichthyoparasitological investigations had been conducted on the Sakarya chub, Squalius pursakensis (Hankó, 1925), an endemic cyprinid fish species in Türkiye. The present study aimed to determine the occurrence and infection parameters of caryophyllidean tapeworms naturally parasitizing this host species. A total of 98 specimens of S. pursakensis were seasonally collected throughout four seasons in 2023 from Sarısu Stream (Eskişehir, Türkiye). Seventeen individuals (17.34%) were found to be infected with one or more caryophyllidean cestodes. Only a single species, Caryophyllaeides fennica , was identified from the intestinal tract. Seasonal variation in infection parameters, as well as differences related to host length and sex, were analyzed. In addition, this study provides the first global description of histopathological alterations caused by C. fennica in a cyprinid fish species. Histopathological examination revealed erosion and degeneration of the intestinal mucosal epithelium at the scolex attachment site, characterized by close contact between the parasite and host epithelial cells, localized tissue destruction, and infiltration of inflammatory cells. The parasites were predominantly located in the anterior to middle regions of the intestine. Furthermore, S. pursakensis is reported as a new host record for C. fennica , thereby expanding the known host range and geographical distribution of this caryophyllidean cestode species.
Nurten Aydoğdu (Tue,) studied this question.