Chaetotaxy and surface structures of the miracidia of Ichthyocotylurus erraticus (Rudolphi, 1809), I. variegatus (Creplin, 1825) and Apatemon gracilis (Szidat, 1928) (Digenea, Strigeidae)

Silver nitrate staining was used to investigate the number and arrangement of argentophillic structures (epidermal plates, sensilla, excretory pores) of three species of strigeid miracidia, Ichthyocotylurus erraticus (Rudolphi, 1809), I. variegatus (Creplin, 1825) and Apatemon gracilis (Szidat, 1928). The epidermal plates of all three species of miracidia were arranged in four tiers according to the formula (6 + 9 + 4 + 3) = 22, while the number and distribution of sensilla were also found to be identical. Modifications to the nomenclature of Dimitrov et al. (1989) for miracidial chaetotaxy are proposed. Scanning electron microscopy (SEM) was also employed to examine the surface structures of deciliated miracidia of Ichthyocotylurus spp., confirming the position and revealing the form of body sensilla.