Lasioglossum (Evylaeus) boreale, belonging to the fratellum-group, is described from material collected at Abisko, northern Sweden. The species is also known from Hokkaido, Japan. The genitalia of the hitherto described males of the fratellum-group are figured. Comments on the biology of L. boreale are added to the description. Notes on the distribution of the palearctic fratellum and the nearctic nigrum groups are also given.