GLANDS ASSOCIATED WITH THE ANTERIOR ADHESIVE AREAS OF THE MONOGENEANS, ENTOBDELLA SP. AND ENTOBDELLA-AUSTRALIS (CAPSALIDAE) FROM THE SKIN OF HIMANTURA-FAI AND TAENIURA-LYMMA (DASYATIDIDAE)

Using scanning and transmission electron microscopy, investigations we re carried out on the anterior adhesive areas of Entobdella sp. from t he skin of Himantura and Entobdella australis from the skin of Taeniur a lymma at Heron Island, Australia. All studies were of parasites deta ched from either host tissue or a substrate. Both species of monogenea ns have two characteristic anteroventral adhesive pads: one on either side of the head, subdivided to form a ''diadem''. Two types of gland cells are associated with the anterior adhesive areas in both species and each cell type produces a different secretion: a rod-shaped secret ion and a smaller, roughly spherical secretion. Each secretion type di ffers in electron-density, with those putatively in the process of for mation being less electron-dense. Both types of secretory bodies are m embrane-bound. Microtubules are evident around forming rod-shaped bodi es. The bounding membranes of the rods of both species show a periodic banding of approximately 12 nm. Both types of secretion are present a t the surface of the adhesive pads in specimens of Entobdella sp. fixe d when detached from the host. The secretory bodies observed in Entobd ella sp. and E. australis from rays show some differences to those rep orted from Entobdella soleae, a parasite of a flatfish teleost. Other ultrastructural differences also exist. We conclude that the types of adhesive secretory bodies may remain constant within genera providing the hosts are similar. (C) 1998 Australian Society for Parasitology. P ublished by Elsevier Science Ltd. All rights reserved.