CHAETOTAXY AND ARMATURE OF ICHTHYOCATYLURUS-ERRATICUS (RUDOLPHI, 1809) AND ICHTHYOCATYLURUS-VARIEGATUS (CREPLIN, 1825) CERCARIAE (DIGENEA, STRIGEIDAE)

The armature and chaetotaxy of Ichthyocotylurus erraticus (Rudolphi 18 09) and I. variegatus (Creplin 1825) cercariae were studied using scan ning electron microscopy (SEM) and silver staining of the argentophili c sensilla. This represents the first detailed investigation of the su rface structures of cercariae belonging to this genus. Both species ex hibited a similar armature, although differences were recorded in the number of spines comprising the pre-oral tuft and the number of rows o f spines in the post-oral collar. The number and the distribution of s ensilla were found to be identical for both species of cercariae. Four types of sensilla, common to both species, were identified that diffe red in cilia length and in the structure of the surrounding collar. Th e distribution of particular sensillary forms was found to be consiste nt in both species.