A new species of Annulatascus, A. hongkongenszs, is described from freshwater habitats. This species differs from other Annulatascus species as ascospores are ellipsoidal, 3-septate, verruculose and are surrounded by a thick mucilaginous sheath. Annulatascus hongkongenszs is described and illustrated with light and transmission electron micrographs, and compared with other Annulatascus species.