PATHOLOGICAL EFFECTS OF PERODERMA-CYLINDRICUM (COPEPODA, PENNELLIDAE)ON THE KIDNEYS OF ITS PILCHARD HOST, SARDINA-PILCHARDUS (OSTEICHTHYES, CLUPEIDAE), FROM TUNISIAN COASTS

Peroderma cylindricum (Heller, 1865) is a pennellid copepod, common on the pilchard Sardina pilchardus (Walbaum, 1792), from the Tunisian co asts. The cephalic area of the parasite displays an important network of cephalic rootlets with dichotomic ramifications inserted mainly int o the anterior part of the host's kidney. A histological study shows t hat these formations alter the kidney's structure. This is confirmed b y the destruction of excretory structures sometimes leading to the app earance of haematoma. The possible role of these cephalic rootlets is compared with their role in other parasitic crustaceans displaying the same formations. It is probable that the presence of this parasite in duces mortality in pilchards, mainly 1 to 2 yr old.