Abstract

During an investigation on intestinal flukes of cattle egret, Ardeola ibis ibis excysted metacercaria and adult worms belonging to family Echinostomatidae Nephrostomum ramosum were recovered. The tegumental surface of N. ramosum was described for the first time using scanning electron microscopy (SEM). SEM observations of excysted metacercaria and adult worms showed some basic differences, excysted metacercaria is conical shaped, ventrally curved, the oral sucker is not developed and the ventral sucker is located in the anterior third of the body, while adult worm has an elongated body with a distinct head collar at the central of which is located on the subterminal oral sucker. The oral and ventral suckers are located closely in the anterior fifth of the body. The total number of collar spines is 40 including five end group ones on each ventral corner. The tegument of the body is wrinkled with transverse grooves and is devoid of spines. The surface of whole body is lacking sensory papillae except the dorsal area of the cephalic region. The results reveal that the characteristic features of N. ramosum, including the number and shape of collar spines, the corrugated surface of the body, absence of tegumental spines and distribution of papillae differed from other echinostomes.

Key words: Trematode, echinostomatidae, Ardeola ibis ibis, tegument, scanning electron microscopy (SEM), Nephrostomum ramosum.