Hamatopeduncularia longiangusticirrata sp. nov. and H. petalumvaginata sp. nov. were collected from Arius maculatus and Nemapteryx caelata, respectively from Tanjung Karang, Peninsular Malaysia. Morphological and molecular investigations were carried out to ascertain the identity of the new species. The two new species differ from previously described Hamatopeduncularia species in the morphology of the male and female reproductive organs. Hamatopeduncularia longiangusticirrata sp. nov. possesses a long penis similar to H. elongata, H. longicopulatrix, H. brisbanensis, H. major and H. petalumvaginata sp. nov., but differs in having a thread-like tapering distal end and can be distinguished from H. brisbanensis and H. major in not having an accessory piece. Hamatopeduncularia longiangusticirrata sp. nov. is also unique in having an ornamented penis initial and a vaginal tube surrounded by fine hair-like structures. Hamatopeduncularia petalumvaginata sp. nov. possesses a simple penis without an accessory piece and a petaloid vaginal opening that resembles the arrangement of petals on a flower. Maximum likelihood trees were constructed from partial 28S and 18S rDNA sequences of the two new species and other ancylodiscoidids to reveal a strongly supported monophyletic branch consisting of the two new species for both markers. According to Lim's classification in 1996 of Hamatopeduncularia species penis type, H. petalumvaginata sp. nov. has been classified within the elegans-type and H. longiangusticirrata sp. nov. is proposed as the longiangusticirrata-type.
A total of 17 species of the genus Bifurcohaptor Jain, 1958 have been reported from two fish families namely Bagridae Bleeker, 1858 (Mystus vittatus (Bloch, 1794), M. tengara (Hamilton, 1822), M. keletius (Valenciennes, 1840), Hemibagrus nemurus (Valenciennes, 1840), Rita rita (Hamilton, 1822) and Sperata seenghala (Sykes, 1839)) and Sisoridae Bleeker, 1858 (Bagarius bagarius (Hamilton, 1822)). Out of these, only two species viz. B. indicus and B. giganticus are found valid in India, parasitizing gills of Mystus spp. and Bagarius sp. Taxonomic studies suggest, present specimen of B. indicus and B. giganticus, both are morphologically close to species described by Jain (1958), except morphometric variations and posses 7 pairs of marginal hooks instead of 6 pairs. Present manuscript delves with the characterization of B. indicus and B. giganticus reported from India, using molecular techniques. Partial mt COI nucleotide sequence based insilico protein analysis and partial 28S and ITS-1 rDNA based phylogenetic analysis, estimated by Neighbour-joining (NJ) and Minimum Evolution (ME) methods revealed that the species of the genus Bifurcohaptor are genetically distinct and valid. The grouping of Bifurcohaptor spp. with other representatives of family Dactylogyridae supports morphology based placement into family Dactylogyridae. Present and previous host-parasite information suggests both Bifurcohaptor spp. are species specialist however, the genus Bifurcohaptor is generalist at generic level.