Chaetotaxy and armature of Ichthyocotylurus erraticus (Rudolphi, 1809) and I. variegatus (Creplin, 1825) cercariae (Digenea, Strigeidae).

The armature and chaetotaxy of Ichthyocotylurus erraticus (Rudolphi 1809) and I. variegatus (Creplin 1825) cercariae were studied using scanning electron microscopy (SEM) and silver staining of the argentophilic sensilla. This represents the first detailed investigation of the surface structures of cercariae belonging to this genus. Both species exhibited a similar armature, although differences were recorded in the number of spines comprising the pre-oral tuft and the number of rows of spines in the post-oral collar. The number and the distribution of sensilla were found to be identical for both species of cercariae. Four types of sensilla, common to both species, were identified that differed in cilia length and in the structure of the surrounding collar. The distribution of particular sensillary forms was found to be consistent in both species.