Rhabdias bufonis (Rhabdiasidae) from the lung of the African common toad, Amietophrynus regularis (Bufonidae) in Egypt. New data on the basis of light and scanning electron microscopic study

Background and Aims: Rhabdias bufonis (Rhabdiasidae) is a nematode parasite of family Rhabdiasidae infecting the lung of amphibians. The present study provides new morphological details for R. bufonis isolated from the lungs of the African common toad, Amietophrynus regularis based on observations of light and scanning electron microscopy. Methods: Forty specimens were collected during the period from March to August 2017 from its natural habitat; the damp, moist fields and gardens at Giza governorate, Egypt. Nematode worms were isolated from the lungs, fixed and then preserved. They were examined using light and scanning electron microscopy with further line drawings. Results: 14 specimens (35%) were found to harbor a large number of Rhabdias. Body of the gravid females were elongated, slender, measured 3.22–9.86 (5.64±0.03) long and 0.09–0.48 (0.23±0.02) mm wide at mid–length. Buccal capsule was with cylindrical lumen and sclerotised walls 13–31 (18 ± 2) long and 16–27 (24 ± 2) mm wide. Ovaries were almost straight. The uteri were located anterior and posterior to the vulva. Uterus filled with large number of eggs (17-42). Eggs were oval in shape, 0.120–0.132 (0.126±0.002) × 0.039–0.812 (0.517±0.02) mm and some of them were with fully developed larvae inside. The tail was comparatively short, gradually tapered, tail length 0.131–0.435 (0.320±0.02) mm long. SEM showed that worms possessed an oval anterior end with a simple, slit like oral opening. The lipless edges of mouth opening bordered with tiny cuticular elevations, radiated outwards. Two pairs of submedian cephalic papillae were observed around the oral opening as well as two amphids. Conclusion: The current study introduced new morphological details for R. bufonis isolated from the Egyptian frog, which was not reported in the previous studies, of them, the morphology of the slit–like mouth opening, the two pairs of cephalic papillae, two amphids and the three pairs of cuticular elevations supporting the area around mouth opening.