REVISION OF NORTH AMERICANAGABUSLEACH (COLEOPTERA: DYTISCIDAE): INTRODUCTION, KEY TO SPECIES GROUPS, AND CLASSIFICATION OF THEAMBIGUUS-,TRISTIS-, ANDARCTICUS-GROUPS

Abstract

AbstractThe first of a planned series of papers revising the Nearctic species of the predaceous diving beetle genus,AgabusLeach, is presented. The genus is defined in the broad sense of Sharp (1882) and Fall (1922). The North American species are divided into species groups and diagnostic characters for group recognition are summarized in a key. Assignment of species to these groups is indicated in a checklist of North American species. Theambiguus-,tristis-, andarcticus-groups are defined, their relationships discussed, and included species revised. Theambiguus-group, which is restricted to North America, contains the speciesA.ambiguus(Say),A.strigulosis(Crotch),A.erythropterus(Say),A.austiniiSharp, andA.klamathensissp.nov. Thetristis-group, which has a Holarctic distribution, contains two species in North America,A.tristisAubé andA.leptapsis(LeConte). The Holarcticarcticus-group is represented byA.arcticus(Paykull) andA.anthracinus(Mannerheim) in North America. For each species, patterns of variation are described, the North American distributions mapped, and ecological information summarized.