Sub-tegumental ventral fibres surrounding the vaginal opening of Entobdella soleae (van Beneden et Hesse, 1864) Johnston, 1929 (Platyhelminthes: Monogenea: Capsalidae).

The distribution of F-actin in the monogenean Entobdella soleae (van Beneden et Hesse, 1864) Johnston, 1929 (Platyhelminthes: Capsalidae) was revealed by staining paraformaldehyde-fixed specimens with FITC-labelled phalloidin. On the ventral surface on the left side of the body, just posterior to the pharynx, a concentrically arranged array of fluorescent fibres was observed, following a circular path around the tiny ventral opening of the vagina. It is assumed that this asymmetrically placed array of actin fibres is contractile and the possible role of these fibres in the assimilation of sperm from an attached spermatophore into the vagina is discussed.