FIRST RECORD OF EUCLINOSTOMUM HETEROSTOMUM FROM THE NATURALLY-INFECTED HERON “ARDEOLA RALLOIDES” IN EGYPT: A LIGHT & SCANNING ELECTRON MICROSCOPY STUDY

Four adult specimens of clinostomatid parasites were recovered from the buccal cavity and oesophagus of a naturally-infected male squacco heron, Ardeola ralloides (Aves: Ardeidae), collected in July 2019 from Giza Province, Egypt. The rate of natural infection was recorded as 10% (1/10). The parasite has the typical body plan organization of Euclinostomum heterostomum Rudolphi, 1809 (Digenea: Clinostomatidae) with minor differences in certain organs measurements. The body dimensions measure 5.57-6.71 × 2.29-2.97 mm (length × maximum body width). The oral sucker locates in the centre of the oral collar and measures 0.36-0.44 × 0.53-0.64 mm, while the ventral sucker locates in the anterior third of body and measures 0.65-1.10 × 0.63-1.27 mm. The right intestinal caecum gives rise to 11-14 diverticula, while the left intestinal caecum gives rise to 12-15 diverticula. The testes are tandem and lie in the posterior third of the body. The anterior testis is U-shaped and measures 0.61-0.70 × 0.85-1.26 mm, while the posterior testis is tripartite and measures 0.60-0.67 × 0.66-0.69 mm. The ovary is intertesticular, dextral to median body plan, and measures 0.22-0.25 × 0.33-0.37 mm. The uterus is pretesticular, intercaecal, filled with hundreds of eggs, and measures 1.54-2.13 × 0.59-1.32 mm. The uterine eggs are ellipsoidal; each measures 0.11-0.12 × 0.06-0.08 mm. The excretory pore is subterminal, intercaecal, and measures 0.12-0.14 × 0.12-0.14 mm. In addition, the surface topographies of the ventral and the dorsal surfaces of body were described.