Intraguild interactions between five congeneric species of Thaparocleidus (Monogenoidea) from the freshwater shark Wallago attu, Lucknow, India.

The fish host (Wallago attu) and monogenoid parasite (Thaparocleidus sp.) have been recorded during 2 years (2011 and 2012) to investigate intra/interspecific interactions among query species (T. sudhakari (Gusev, 1976) Lim, 1996; T. indicus (Kulkarni, 1969) Lim, 1996; T. gomtius (Jain, 1952) Lim, 1996; T. yogendraii Agrawal, 1981 and T. wallagonius Jain, 1952) in the light of parasitic worm burden, morphological and molecular data. Each species is highly host specific (oioxenous), with a specialized functional niche. Being niche specialists, they exhibit niche overlapping along with co-existence due to reproductive barrier. Furthermore, a molecular marker, affirming clear-cut genetic variation in spite of structural entities, provides evidence for infra-speciation as well as co-speciation.