Female morphology of Philometra hyderabadensis Rasheed, 1963 (Nematoda: Philometridae), a little-known parasite of the catfish Wallago attu Bloch & Schneider in India, as revealed by SEM observations.

The female morphology of the nematode Philometra hyderabadensis Rasheed, 1963 (Philometridae) is described based on subgravid specimens found in the abdominal cavity and intestine of the catfish (wallago) Wallago attu Bloch & Schneider from the Purna River and Yeldari Reservoir, Parbhani District, Maharashtra State, India collected in August 2010 and January 2011, respectively. Light and scanning electron microscopical examination made it possible to study in detail the morphology of this little-known species. In contrast to the original species description, the female cephalic end was found to bear 10 small cephalic papillae: four submedian double papillae of the external circle and six single papillae of the internal circle, of which two are lateral and four submedian. The anterior end of the oesophagus is only slightly inflated and there are three distinct oesophageal teeth protruding from the mouth. Previously, P. hyderabadensis had been known only from a single female specimen collected in Hyderabad, India and deposited in the Natural History Museum, London. Consequently, the present finding represents the second documented record of this species, 50 years after its original description. Philometra suraiyae Kalyankar, 1971 is considered a junior synonym of P. hyderabadensis.