Hybomitra aequetincta and H. zonalis (Diptera: Tabanidae): identification key, distribution and seasonal abundance in Quebec-Labrador.

The closely related tabanids Hybomitra aequetincta (a Holarctic species) and H. zonalis (Nearctic) occur together only in the area of Quebec and Labrador. Because of their variability, specimens from northern boreal forest and forest-tundra areas were difficult to identify. An analysis of several parameters on 386 specimens was made and a key to the adults devised. Distribution maps of each species in the Quebec-Labrador peninsula are presented and discussed. H. aequetincta is a boreal species and H. zonalis is boreal-temperate. The seasonal abundance of adult populations was analysed for several years in northern latitudes.