PATTERN OF DAUGHTER SPOROCYST (DIGENEA, FAUSTULIDAE) INFESTING TAPES DECUSSATA (L.)
(BIVALVE, VENERIDAE) FROM THE MEDITERRANEAN

Ramadan A. M. Ramadan1 and Amaal M. Ahmad2

1 Fish Diseases Department, Central Labratory For Aquaculture Research, Agriculture Research Center, Ministry of Agriculture, Egypt.

2 Zoology Department, Faculty of Science, Zagazig University.

Received 2/ 1/ 2012 Accepted 25/ 1/ 2012

Abstract

A total of 1262 clams (Tapes decussata) were examined, from Port Said coastal zone. Of these, 85 (6.7%) clam Tapes decussata were taken at monthly intervals between May 2009 and June 2010 to demonstrate variations in percentage infection by Cercaria lata (Faustulidae) with season, and size of host. sizes and season are the main important in determining the percentage infection by Cercaria lata. The maturity of the infection and the mean number of metacercariae per daughter sporocyst from the same host are also largely determined by season. Summer months reveal high peaks of infection, which are more than triple the mean percentage infection, occur in March or April . Parasites were the lowest in winter months. In emerging from the host, Tapes decussata, the cercariae are expelled through the excurrent siphon. They swim about in the sea water with the body folded upon itself. Cercaria lata characterized by Excretory vesicle Y-shaped with long arms reaching anterior to intestinal bifurcation. Tail tubule communicating with bladder. Surface of tail lacking spines provided with annular folded membranes. Twenty-five pairs (24–27) of setae bundles arranged laterally along the tail.