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

Abstract

Background and AimsRhabdias sp. (Rhabdiasidae) is a nematode parasite of family Rhabdiasidae infecting the lung of amphibians. The present study provides new morphological details for Rhabdias bufonis isolated from the lungs of the African common toad, Amietophrynus regularis based on observations of light and scanning electron microscopy (SEM).MethodsForty specimens were collected from its natural habitat: the damp, moist fields and gardens at Giza governorate, Egypt. Worms were isolated from the lungs, fixed and then preserved. They were examined using light and SEM with further line drawings.ResultsFourteen specimens (35%) were found to harbor Rhabdias with an intensity of three to five worms per host. Bodies 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) wide at mid-length. Buccal capsule was with cylindrical lumen and sclerotized walls. Ovaries were almost straight. The uteri were located anterior and posterior to the vulva. Uterus were filled with a large number of eggs (17–42). Eggs were oval in shape and some of them were with fully developed larvae inside. The tail was comparatively short, gradually tapered. SEM showed that worms possessed an oval anterior end with a simple, slit like oral opening. The lipless edges of the mouth opening were bordered with tiny cuticular elevations, radiated outwards. Two pairs of submedian cephalic papillae were observed around the oral opening as well as two amphids.ConclusionThe current study presents new morphological details for R. bufonis isolated from the African common toad. Also, 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 were investigated.

New host record, Sclerophrys regularis (Bufonidae), for Rhabdias africanus (Rhabdiasidae, Kuzmin, 2001) based on molecular and morphological evidence

“…The entity and number of papillae on R. africanus follows the template of circumoral structures in some free-living Rhabditidae ( Chitwood and Chitwood, 1938 ). This arrangement has been reported in several Rhabdias species, e.g., R. bufonis ( Morsy et al, 2018 ), R. picardiae ( Svitin et al, 2018 ), and R. ranae ( Tkach et al, 2006 ). Difference in the circumoral structure could be explained by the growth of adult worms and migration at the cephalic end resulting in the relocation of the apical features ( Baker, 1979 ).…”

“…Rhabdias africanus differs from Rhabdias bufonis described from Sclerophrys regularis in Egypt ( Morsy et al, 2018 ) by the shape and length of the body (greater than9.86 mm in R. bufonis ), the rounded oral opening, lateral amphibs, labial papillae with tapered tips, pre-equatorial vulva, and overlapping ovaries.…”

“… R. aegyptiaca Rhabdias sp. R. bufonis R. bufonis R. africanus Rhabdias species El–Garhy and Garo Saad et al (2009) Moravec et al (1987) Morsy et al (2018) Present study Author −2006 –– N = 30 N = 10 N = 28 N = 40 No. of worms 8–10 5.2–12.5 2.99–13.02 5.64 ± 0.03 9.67 ± 2.97 body length (mm) (3.22–9.86) (6.61–13.96) –– 225–400 –– –– 291.4 ± 105.8 body width oesophago-intestinal junction (200.3–444.1) 300–500 200–700 136–476 230 ± 20 311 ± 97.6 Body width at vulva (90–480) (210.3–470.9) –– –– –– –– 228.8 ± 44.6 Body width at anus (177.6–258.8) –– 10–32 15 18 ± 2 34.4 ± 7.9 buccal cavity length (13–31) (22.5–34.4) –– –– 21 24 ± 2 17.3 ± 4.4 buccal cavity depth (16–27) (10.8–20.2) 550 250–500 288–510 180 ± 20 503.9 ± 40.5 oesophagus length (270–630) (442.9–542.7) ––...…”

“…Globally, about 40 species of Rhabdias infect the lungs of amphibians and reptiles ( Tkach et al, 2014 ). In Egypt, Rhabdias species have been reported from bufonids in subtropical areas ( Moravec et al, 1987 , Morsy et al, 2018 ). In the present study, we provided a morphological description of R. africanus , as a new record from Egypt, with molecular characterization based on the 18S rRNA gene and ITS-28S region.…”

“…Only three species of Rhabdias have been described in Egypt based on light microscopy: R. bufonis ( Moravec et al, 1987 , Morsy et al, 2018 ), Rhabdias aegyptiaca ( Elgarhy and Garo, 2006 ), and Rhabdias sp. ( Saad et al, 2009 ).…”