A new monorchiid (Digenea) cercaria parasitising the purple clam Amiantis purpurata (Veneridae) from the Southwest Atlantic Ocean, with notes on its gonadal effect.

FLORENCIA CREMONTE; MARINA A, KROECK; MARTORELLI, SERGIO R

FOLIA PARASITOLOGICA

FOLIA PARASITOLOGICA

Año: 2001 vol. 48 p. 217 - 223

0015-5683

An unnamed microcercous cercaria (Digenea: Monorchiidae), parasite of Amiantis purpurata (Lamarck, 1818) (Bivalvia: Veneridae) and its corresponding metacercaria from the province of Buenos Aires and Patagonian coast on the Southwest Atlantic Ocean, are described. The cercaria described in the present paper differs from the three other monorchiid microcercous cercariae [Lasiotocus minutus (Manter, 1931), Lasiotocus elongatus (Manter, 1931) and Cercaria caribbea XXXVI Cable, 1956] mainly because of the extension of the excretory vesicle and the location of the ventral sucker. Cercariae artificially extracted from sporocysts encyst in a dish and form metacercariae enveloped by a gelatinous sac with two prolongations, which are used to adhere to the substratum. The monorchiid described in the present paper has a life cycle similar to those of L. minutus and L. elongatus, although the adult stage of the present species is still unknown. Their larvae are similar in morphology and have venerid clams as their first hosts. The presence of a monorchiid larva is reported for the first time in the Southern Hemisphere. Its monthly prevalences, ranging from 0 to 25% (mean: 8.3%), are given from the Patagonian coast. The infection seems to cause castration because during March through May, when most gametes were produced in uninfected individuals, 81% of the infected individuals were not producing gametes.