Arctoa
Bryol. Europ. 1: 151. 1846 ,.
| Taxon | Illustrator ⠉ | |
|---|---|---|
 | Arctoa hyperborea | Patricia M. Eckel |
Plants in dense tufts, dark green to yellowish-brown, shiny. Stems (0.5–) 1–2 (–5) cm, branches simple, sparsely radiculose. Leaves lanceolate, subulate, erect-spreading, sometimes falcate-secund; margins erect, entire, or serrulate near the tips; costa excurrent as an awn, narrow, stereids poorly differentiated from median guide cells; distal laminal cells rectangular to subquadrate, smooth or slightly mammillose; basal laminal cells elongate, smooth, sometimes porose, alar cells sometimes differentiated and inflated. Perichaetial leaves with a sheathing base. Sexual condition autoicous. Seta solitary, 3–6 mm, erect, stout, yellow. Capsule erect, exserted or immersed in perichaetial leaves, symmetric, obovoid, constricted below mouth, furrowed when dry, urn 0.5–1.2 mm; operculum obliquely rostrate; peristome single, of 16 redbrown teeth, divided halfway into two segments, vertically or irregularly striolate. Calyptra cucullate, smooth. Spores spheric, 16–30 µm, finely roughened, green.
Distribution
North America, Europe, Asia
Discussion
Species ca. 4 (3 in the flora).
A rare northern and alpine genus, Arctoa occurs on rock or soil and is distinguished by its medium-sized, Dicranum-like habit, with poorly differentiated stereid and guide cells. It may be confused with Kiaeria, which differs by a longer seta, and capsules often strumose, with narrow mouths.
Selected References
Lower Taxa
Key
| 1 | Peristome teeth not wide-spreading; distal leaf cells 1-2:1; costa short-excurrent. | Arctoa hyperborea |
| 1 | Peristome teeth wide-spreading; distal leaf cells 2-5:1; costa long-excurrent | > 2 |
| 2 | Capsule straight, immersed; seta short; awn entire. | Arctoa anderssonii |
| 2 | Capsule curved, exserted; seta long; awn toothed. | Arctoa fulvella |