The examination of gill parasites from P. mahakamensis Pouyaud, Gustiano & Teugels, 2002 (Siluriformes, Pangasiidae) in Southeast Asia revealed the presence of three species of Monogenea. One (Thaparocleidus caecus (Mizelle & Kritsky, 1969)) had been previously described. The other two, belonging to Thaparocleidus Jain, 1952 (Monogenea, Ancylodiscoididae) as defined by Lim (1996) and Lim et al. (2001), are considered new species: T. pouyaudi n. sp. and T. teugelsi n. sp.