Redescriptions of Ligophorus cephali Rubtsova, Balbuena, Sarabeev, Blasco-Costa & Euzet, 2006 and L. chabaudi Euzet & Suriano, 1977 based on original material from the Black Sea, the Mediterranean Sea and the Sea of Japan are presented. A comparison of samples of these two species from different regions was carried out with the aid of principal components analysis. The occurrence of L. chabaudi on Mugil cephalus in the Sea of Japan was confirmed. The functional morphology of the male copulatory organ was examined, and the use of the shape of this structure in the taxonomy of Ligophorus Euzet & Suriano, 1977 is discussed.