Abstract: AIM:To observe the fine structures of tegument of Echinochasmus liliputanus.
METHODS:Adult worms of E.liliputanus obtained from dogs experimentally infected with
metacercariae of the worm were observed by scanning electronmicroscopy. RESULTS: Almost the
whole body surface of the parasite is covered with shell- like spines exceptthat of the head
collar,ventral sucker and posterior part of the body.The spines arranged in scrow rows are
basically in the same sizes and shapes,but the intervals between them increase gradually from the anterior to the posterior part of the body. Three types of sensory papillae are found on the body surface, i. e. , one with sensory hairs and two without sensory hairs. The sensory papillae with sensory hairs are widely distributed on the surface of the oral sucker, head collar, and anterior two third of the body. On the acetabulum located 32 protruded papillae without sensory hairs. The three types of papillae are also present on the oral sucker. Of the three types of papillae, those with sensory hairs are the most abundant ones throughrut the entire tegument of the worm. CONCLUSION: The ultrastructural characteristics of the tegument of E. liliputanus are considered to be related to the evolutional adaptation to its parasitic environment,which may be taken as one of the bases in taxonomic studies.

Key words: Trematode, Echinochasmus liliputanus, tegumental spines ultrastructure, SME