The genera Ceratomyxa Thelohan, 1892, Leptotheca Thelohan, 1895 and Sphaeromyxa Thelohan, 1892 (Myxosporea : Bivalvulida) in gadid fish of the northeast Atlantic

The gall-bladders of four species of gadid fish from the North Sea and Norw egian waters were examined for myxosporeans. The host species were cod Gadu s morhua L. (350 examined), haddock Melanogrammus aeglefinus (L.) (592 exam ined), saithe Pollachius virens (L.) (205 examined) and whiting Merlangius merlangus (L.) (368 examined). Four species of myxosporeans are redescribed from these fish. Ceratomyxa arcuata Thelohan, 1892 was the most common spe cies and was found in whiting (42.8%) and cod (0.6%). Leptotheca informis A uerbach, 1910 was found only in whiting (6.5%). L. longipes Auerbach, 1910 was found only in haddock (6.2%). Sphaeromyxa hellandi Auerbach, 1909 was f ound in haddock (9.1%) and whiting (0.3%). None of the saithe examined, and no cod or haddock from Norwegian waters, was infected with these myxospore ans. All four species appear to have distributions limited to the Northeast Atlantic, with S. hellandi having a more northern distribution than the ot her three. The validity of reports of C. arcuata, L. informis and L. longip es from outside this area is discussed.