REVISION OF NORTH AMERICANAGABUSLEACH (COLEOPTERA: DYTISCIDAE):LUTOSUS-,OBSOLETUS-, ANDFUSCIPENNIS-GROUPS

Abstract

AbstractSpecies ofAgabusof thelutosus-,obsoletus-, andfuscipennis-groups, as defined by Larson (1989), are revised. Members of thelutosus- andobsoletus-groups are restricted to the Cordilleran and Great Plains regions of temperate western North America. Within this region, the species of each group are largely parapatric. Three species are assigned to thelutosus-group:A.lutosusLeConte along the Pacific Coast;A.griseipennisLeConte in the Great Basin, Rocky Mountain, and Great Plains regions; andA.rumppiLeech in the southern deserts.Agabus lutosusandA.griseipennishybridize in the Pacific Northwest;A.lutosus mimusLeech is synonymized withA.lutosus. Theobsoletus-group contains five species:A.obsoletusLeConte,A.morosusLeConte, andA.ancillusFall along the Pacific Coast and the Sierra Nevada Mountains;A.hoppingiLeech in the Sierra Nevada Mountains; andA.obliteratusLeConte, containing two subspecies,A.o.obliteratusandA.o.nectrisLeech, new status, with a wide range including the Great Plains and Cordillera but not reaching the Pacific Coast. The four species of thefuscipennis-group,A.ajaxFall,A.coxalisSharp,A.fuscipennis(Paykull), andA.infuscatusAubé, are boreal and all exceptA.ajaxare Holarctic.Agabus coxalisis restricted to northwestern North America, the other three species are transcontinental.For each species the following information is provided: synonymy, description, and illustrations of taxonomically important characters; notes on relationships, variation, distribution, and ecology; and a map of North American collection localities. Group diagnoses and keys to the species of each group are presented. A correction to the key to species groups of North AmericanAgabus(Larson 1989) is made with the addition of a couplet to include theobsoletus-group. Lectotypes are designated forA.discolorLeConte andA.obliteratusLeConte.