ABSTRACT
During the parasitological examination of molluscs Abra segmentum obtained from the Black Sea basin, parthenitae belonging to the family Faustulidae were found. The cercariae were obtained by natural emergence and were studied using differential interference contrast microscopy and scanning electron microscopy. Specimens resemble Cercaria pennata ex Tapes rugatus which was described from the Sevastopol area, in the shape and length of the body, tail length, location and shape of internal organs, suckers, pharynx, testicular rudiments, and the number and position of longitudinal lamellae on the tail finlets. To date, there are only limited descriptions of the parthenitae of C. pennata without detailed measurements, thus the taxonomic position of the individuals studied needs thorough revision and molecular verification. According to the molecular analyses, C. pennata was identical to that of published sequences of Pronoprymna ventricosa.