HYMENOCHIRINE ANURANS (PIPIDAE) AS TRANSPORT HOSTS IN CAMALLANID NEMATODE LIFE-CYCLES

A parasitological survey of aquatic hymenochirine toads (Pipidae) from tropical Africa indicated the occurrence of camallanid larvae in thes e hosts is a regular ecological phenomenon. Pseudhymenochirus merlini at one site in western Sierra Leone was infected by third-stage larvae of a Camallanus species occurring in the intestine. Third- and fourth -stage larvae of a distinct Camallanus species occurred in the stomach and intestine of P. merlini at another locality, also in western Sier ra Leone. An imported pet trade consignment of Hymenochirus curtipes f rom Nigeria contained third-stage procamallanine larvae, some of which showed morphological changes preceding the third moult. Comparable sp ecimens occurred in museum collections of H. boettgeri from the Democr atic Republic of the Congo. Procamallanines were localised in the host 's stomach. The morphology of camallanid larvae recovered is described , and their possible relationships considered. Predation on hymenochir ines might present an important transmission route for these parasites between copepod intermediate hosts and larger aquatic predators. Howe ver, the final hosts and their trophic relationships with hymenochirin es are unknown. Regardless of its significance for transmission, the s urvival ability of lan al stages in non-definitive host vertebrates mi ght have predisposed camallanid lineages to evolutionary host changes and contributed to the wide dispersal of the family.