Arctoa
Autoicous or paroicous (not in Victoria). Asexual propagules absent. Tufts on rocks, soil (not in Victoria) or rarely on tree (not in Victoria) or shrub bark (not in Victoria). Stem simple or sparingly branched, with scattered rhizoids near base; central strand present. Leaves subulate from a lanceolate base, erect-spreading (not in Victoria) or falcate-secund when moist, scarcely altered or flexuose or sometimes slightly crisped when dry; apex acuminate, with an awn; costa percurrent or excurrent; margin entire or serrulate near apex, plane or slightly incurved near apex (not in Victoria), without a border; laminal cells linear, rectangular or rarely subquadrate, smooth or mamillose (not in Victoria) or papillose toward apex (not in Victoria), unistratose or bistratose along margins or toward apex; alar cells well-differentiated, short-rectangular to quadrate, inflated or not, hyaline or brown, unistratose or bistratose. Capsule exserted or emergent (not in Victoria), erect or inclined, straight or curved, obovate (not in Victoria), ovoid or cylindric, furrowed or not when dry, with a well-differentiated annulus or rarely annulus poorly differentiated (not in Victoria). Calyptra cucullate, smooth, glabrous. Operculum obliquely rostrate. Peristome of 16 teeth divided to half way to 2/3 of their length into two filaments.
Eight species, six of which are from the Northern Hemisphere in alpine to subpolar areas and three occur in the Southern Hemisphere including one extending to South America from the Northern Hemisphere, one endemic to New Zealand and one shared between south-east Australia, New Zealand and southern South America.
Kiaeria and Arctoa were shown to be closely related in a phylogeny of chloroplast and mitochondrial DNA sequences and the two similar genera have been merged (Fedosov et al. 2021). Kiaeria was previously recognised in the Dicranaceae and the sole Victorian species. A. pumila (Mitt.) Fedosov, Jan Kučera & M.Stech was previously included in Kiaeria.
SpinningFedosov, V.E.; Fedorova, A.V.; Larraín, J.; Santos, M.B.; Stech, M.; Kučera, J.; Brinda, J.C.; Tubanova, D.Y.; Von Konrat, M.; Ignatova, E.A.; Ignatov, M.S. (2021). Unity in diversity: phylogenetics and taxonomy of Rhabdoweisiaceae (Dicranales, Bryophyta). Botanical Journal of the Linnean Society 195: 545–567.