Holotype: Atrichopsis magellanica Cardot, Revue Bryol. 39: 95. 1912. nom. illeg. (=Polytrichum compressum Hooker f. & Wilson, Lond. Jour. Bot. 3: 539. 1844.)
Atrichopsis compressa (Hook. f. & Wilson) G. L. Smith is a distinctive species, closely allied to Notoligotrichum, but distinguished by its elamellate leaves, and the distinctive structure and coloration of the leaf margin. The morphology and taxonomy of Atrichopsis are discussed at length in a recent paper (Smith, 1969a).
Atrichopsis is at present known only from a few localities in Fuegia and the Falkland Islands. It is probable, however, that this genus or its immediate ancestor was formerly more widely distributed, since Notoligotrichum crispulum (Hook. f. & Wilson) G. L. Smith, which seems to be the taxon most closely related to Atrichopsis, is a native of New Zealand and Tasmania. Notoligotrichum tapes (C. Müll.) G. L. Smith, of Fuegia and South Georgia, bears only a few interrupted lamellae on the leaf nerve, but probably represents a parallel development, since in A'', tapes the whole lamina is unistratose. In Atrichopsis, the structure of the lamina, rather than having been reduced together with the lamellae, remains essentially unmodified.