First spermatological data on the digenean genus Ityogonimus derived from the description of sperm characters of Ityogonimus ocreatus (Brachylaimidae: Ityogoniminae).

The present study describes the ultrastructural organization of the spermatozoa of the brachylaimid digenean Ityogonimus ocreatus (Ityogoniminae) by means of transmission electron microscopy (TEM). Live digeneans were collected from the digestive tract of an Iberian mole Talpa occidentalis (Eulipotyphla, Talpidae) captured accidentally during a vole pest control campaign in Priesca (Asturias, Spain). The TEM study reveals that the I. ocreatus sperm are filiform, tapered at both extremities, and have two 9+'1' trepaxonematan axonemes, external ornamentation of the plasma membrane associated with cortical microtubules, spine-like bodies, two bundles of parallel cortical microtubules and one mitochondrion overlapping the anterior part of the nucleus. The external ornamentation of the plasma membrane is located in the posterior part of the anterior region. The maximum number of parallel cortical microtubules (45) is located in the anterior part of the sperm cells. Our results are compared with the available data on the family Brachylaimidae, especially on the other Ityogoniminae studied to date (Scaphiostomum palaearcticum).