Mosses from the Mackenzie Mountains, Northwest Territories

Abstract

A recent collection by W. J. Cody (Canada Department of Agriculture) from the Mackenzie Mountains, continental Northwest Territories, arctic Canada, included 2 mosses of some phytogeographical interest. These were collected on the Plains of Abraham (64°30'N, l27°l3'W), on a shattered limestone plain at approximately 1,400 m altitude. The specimen (containing both species) was collected on 9 July 1970, W. J. Cody, collection number 19078. Bryum wrightii Sull. and Lesq. Cody 19078, with numerous sporophytes. This is the first report of this moss from the continental Northwest Territories, and a substantial southwestward range extension. The species is also known from a few of the Queen Elizabeth Islands1, Banks Island, Southampton Island, and Greenland, but it is rare and local throughout its distribution. Voitia hyperborea Grev. and Arnott. Cody 19078a, a few plants, with sporophytes. This species, whose distribution was recently mapped, was known from the eastern part of the continental Northwest Territories but not from the western part. The present collection extends the species' range to the southwest, and provides the closest locality yet to the Alberta populations of its vicariant, Voitia nivalis Hornsch. The Plains of Abraham specimens are, however, definitely the high arctic V. hyperborea. The presence of Bryum wrightii and Voitia hyperborea on a high-altitude plain which was unglaciated in the Pleistocene is significant. They have probably remained in this locality during the Pleistocene Glaciations. Both species undoubtedly also survived the glaciations in other Nearctic refugia. Bryum wrightii is also known from Banks Island but has not yet been reported from unglaciated Arctic Alaska. Voitia hyperborea seems also to have survived glaciation in several other widely scattered refugia, including arctic Alaska, northern Ellesmere Island, and Greenland. The discovery of these 2 mosses in an unglaciated part of the continental Northwest Territories may well indicate that the Plains of Abraham and other high unglaciated plateaus in the Mackenzie Mountains have a flora rich in high arctic bryophytes.