Scanning electron microscope observations on the digenean intestinal parasite Astiotrema reniferum (Plagiorchiidae)

The body surface of adult digenean intestinal parasite Astiotrema reinferum (Looss, 1898) Stossich, 1904 has been studied using scanning electron microscopy (SEM). The posterior region of the body forms a slender stalk terminating with two ventrolateral lobes. The lobes are armed with numerous large spine that are sharply pointed and orientated in all directions. There are regional variations in the distribution of spines all-over the body. The spines are abundant on the general body surface of the head region, the rim of the oral sucker, the inner lip of the ventral sucker and on the posterior ventrolateral lobes. No spines were observed on the genital pore and on the excretory opening. The sensory papillae found on both the oral and ventral suckers are arranged in a bilateral symmetrical patterns. They are dome shaped but some of them possess a short knob-like process and others have no process. The papillae are more abundant on the oral sucker than on the ventral sucker. The possible functions of the spines and sensory papillae are discussed relative to their position.