Coccidian parasites of intertidal fishes from Wales: systematics, development, and cytochemistry.

Examination of littoral fish Blennius pholis and Cottus bubalis caught at Aberystwyth and Porth Cwyfan, Wales, U.K. revealed 2 species of coccidia. Eimeria dingleyi sp. n. Oocysts spherical (16.1-19.2) to subspherical (13.9-14.2 X 18.8-20.0) micron, with thin walls; sporulation outside the host to produce ellipsoid sporocysts; endogenous phases in epithelial cells throughout intestine; 26 of 58 B. pholis infected. Eimeria variabilis (Théohan) Reichenow. Oocysts spherical (11.9-14.6) to subspherical (9.2-10.9 X 13.9-14.3) micron, sporulation in lining of pyloric ceca and rectum; previously unrecorded schizonts and gametocytes present; 21 of 25 C. bubalis infected. Electron microscopy revealed that the oocyst wall of E. variabilis consists of a thin membrane whereas the sporocyst wall is thick and 3-layered. Typical oocyst wall-forming bodies were absent from the macrogamete. Cytochemical tests on the endogenous stages of E. dingleyi and E. variabilis indicated that in general they resembled other coccidia in their chemical constitution.