A new species of black fungus gnat from Canada, Peyerimhoffia jaschhoforum sp. n., is presented with a description, illustrations, biotope information and a brief discussion of the placement and concept of the genus Peyerimhoffia. P. jaschhoforum is characterized by a unique gonostylar structure where the apex is hollowed but not enclosed and contains a mass of mega setae housed within. P. jaschhoforum was reared from decomposing jack pine (Pinus banksiana Lamb.) deadwood using both in-situ and ex-situ photoeclectors. We documented three additional specimens originating from Fennoscandia that resemble P. jaschhoforum but differ based on a broader tegmen, placement of setigerous papillae behind the tegmen and the fused intercoxal area. Based on this, these specimens are assigned to a new subspecies, Peyerimhoffia jaschhoforum fennoscandica ssp. n.