Identification tools of Diplostomum spathaceum Rudolphi, 1819 (Diplostomida: Diplostomidae), a trematode parasite of herring gull (Larus argentatus)

Abstract

Specimens of the genus Diplostomum von Nordmann, 1832 (Trematoda, Diplostomidae) were collected from the intestine of the herring gull, Larus argentatus (Laridae), from El-Manzala Lake (Port Said City, Egypt). This parasite species was morphometrically, morphologically, and molecularly studied using the internal transcribed spacer (ITS1-5.8S-ITS2) gene region. The presence of a trematode species of Diplostomum spathaceum Rudolphi, 1819 (Diplostomidae) was observed in 70 % of the examined gull species. This species has generic features of the genus Diplostomum. Distinct criteria that discriminated this species from congeners were the division for body parts, the egg-shaped forebody with a smaller length than the hind body, the ventral sucker being smaller in size than the oral one, the position of the ventral sucker being near to the holdfast, vitellaria was compact and rarely extend anteriorly to the holdfast organ, and smaller egg size. Partial ITS1-5.8S-ITS2 sequences from diplosomite recovered in this study showed that they grouped with members of the genus Diplostomum and formed a monophyletic group supporting the morphological description. Findings obtained from molecular analysis are consistent with data from morphological classification where the parasite recorded was morphologically similar to Diplostomum spathaceum with a first record in Egyptian gulls.