Species of Echinococcus: pattern and process

Although classification and nomenclature within the cestode genus Echinococcus has, historically, been controversial, the past 20-30 years have provided a period of relative stability. Recent calls for taxonomic revision in the genus have therefore created something of a stir. In this article, Alan Lymbery and Andrew Thompson describe the reasons for the new controversy, and suggest that the problem can only be resolved by agreement on an appropriate species concept and on operational procedures for implementing that concept.