Changing concepts in species diversity in the northeastern Pacific

Changing concepts in species diversity are reflected in recvaluation of cosmopolitan species and concomitant increase in new species previously included within wide ranges of variation. This information is important for biodiversity totals but also for determining environmental impacts of coastal developments. If most species are perceived to have near-worldwide distribution with little speciation occurring in local environments, identification of species may be negated and unnoticed rare species lost to development. Examples of diversity hidden by prior cosmopolitan identifications were found in studies off Santa Barbara, California. Current re-examination of ‘Parasmittina trispinosa’ collected from Alaska to the Galápagos indicates that this species may not occur in the eastern Pacific; instead a complex of described and undescribed species occurs. Similar reexamination of presumed species could increase species diversity extensively.