MICRO-EVOLUTIONARY IMPLICATIONS OF ALLOZYMIC AND MORPHOMETRIC VARIATIONS IN SEALWORMS PSEUDOTERRANOVA SP (ASCARIDOIDEA, ANISAKIDAE) AMONG SYMPATRIC HOSTS FROM THE SOUTHEASTERN PACIFIC-OCEAN

We found significant morphometric and electrophoretic differences betw een sealworm larvae collected from four sympatric fish host species of f the central coast of Chile. The South American sea lion, Otaria byro nia, is a suitable host and most likely the only definitive host speci es in the study area. Morphological patterns of caudal papillae in adu lt males collected from sea lions and electrophoretic evidence from la rvae and adults substantiate our conclusion that they belong to just o ne, new species yet to be described. The genetic and morphometric diff erences found between sealworm larvae from sympatric fish hosts may be due to selective pressures arising from the internal environment of t he intermediate hosts, although they may serve only for passing sequen tial filters along the life cycle. The discussion deals with the roles that definitive and intermediate hosts may play in the micro-evolutio nary processes of sealworms.