1. School of Biological Sciences, Southern Illinois University, Carbondale, Illinois 62901-6501.
2. Instituto de Biología Subtropical (IBS)-CONICET-CCT Nordeste, Bertoni 85 (3370) Puerto Iguazú, Misiones, Argentina.
3. The Harold W. Manter Laboratory of Parasitology, W 529 Nebraska Hall, University of Nebraska–Lincoln, Lincoln, Nebraska 68588-0514.