M. S. Ahmed, K. S. Ahmed, W. A. Khan, H. Ali, F. Ollevier and D. L. Ray*
Department of Zoology, University of the Punjab, Quaid-e-Azam Campus, Lahore 54590, Pakistan.
*Laboratory of Aquatic Ecology and Evolutionary Biology, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
**Laboratory of Protozoology, Institute of Tropical Medicine and Hygiene, B-2000 Antwerp, Belgium.