Three new species of Bychowskyella Achmerow, 1952 (Monogenea) from Peninsular Malaysia

Three new and one previously described species of Bychowskyella were collected from the gills of four species of freshwater catfish in Peninsular Malaysia. They are Bychowskyella teysmanni n. sp. from Clarias teysmanni, B. sisoris n. sp. from Glyptothorax major, B. baueri n. sp. from Silurichthys hasselti , and B. tchangi from Clarias macrocephalus . B. teysmanni n. sp. differs from B. tchangi in having two pairs of large marginal hooks. B. sisoris n. sp. is unique in possessing two onchia, while B. baueri n. sp. differs from previously described Bychowskyella species in the structure of the dorsal onchium. C. macrocephalus is a new host record for B. tchangi in Peninsular Malaysia.