Utilizacion de la morfologia de las larvas merocercoides presentes en moluscos, en la dilucidacion de la taxonomia de las especies de Rhodobothrium (Cestoda: Tetraphyllidea)

Abstract

Lamellibranch mollusks have been reported as intermediate hosts of Tetraphyllidean cestodes. These platyhelminths end their life cycles in the elasmobranch fishes. Larval cestodes belonging to the Scolex pleuronectis type have been found in different parts of the world parasitizing bivalve mollusks. Bahamonde & López (1962) described 2 types of Tetraphyllidean cestodes in the Chilean clam Mesodesma donacium: a plerocercoid in the intestine and a merocercoid on the visceral mass. By means of the in vitro culture as well as by dissection of the spiral valves of rays, it was possible to observe how these larvi became adult parasites (Hamilton & Byram 1974; Carvajal 1977, Campbell & Carvajal 1979, Campbell & Carvajal 1982). Nevertheless up to now it has not been possible to clarify 1) How Mesodesma donacium became infested and 2) Which are their developmental stages previous to the merocercoid stage. The importance of the external morphology of the merocercoid larvae in the taxonomic identification of the species belonging to the genus Rhodobothrium is established.