New data on the morphology of Dichelyne hartwichi (Nematoda, Cucullanidae), a parasite of freshwater tetraodontid fishes (Tetraodon spp.) in Thailand

Parasitological examination of the freshwater fish Tetraodon palembangensis Bleeker (Tetraodontidae, Tetraodontiformes) (n = 19), imported along with other ornamental fishes from Thailand into the Czech Republic in October 1998, revealed the presence of male specimens of the nematode Dichelyne (Dichelyne) hartwichi Moravec, Wolter et Körting, 1999 (Cucullanidae) (prevalence 11%, intensity 1). Their detailed study using light and scanning electron microscopy (the latter used for the first time in this species) enabled the redescription of this hitherto little-known species and the recognition of considerable morphological and biometrical intraspecific variability. The finding of this species in T. palembangensis represents a new host record.