 They resemble the smaller 'northern cave' species "Vespadelus caurinus", except for the darker colouring lacks a yellowish hue.The first description, published as Eptesicus douglasi, was made by Darrell Kitchener in 1976.The epithet was emended by Kitchener to "douglasorum" in 1987, the same year another systematic treatment transferred that taxon to a subgeneric arrangement within "Pipistrellus", allied to "Pipistrellus" ("Vespadelus").