Arctoa

Bruch & Schimper

Bryol. Europ.1: 151. 1846 ,

Etymology: Greek arktos, bear, alluding to an arctic or northern distribution
Synonyms: Dicranum Arctoa
Found in FNA Volume 27. Treatment on page 362. Mentioned on page 359, 363.
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 red-brown 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.

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
Facts about "Arctoa"
AuthorSteven G. Newmaster +
EtymologyGreek arktos, bear, alluding to an arctic or northern distribution +
IllustratorPatricia M. Eckel +
Referenceallen1998a +
SynonymDicranum Arctoa +
Taxon nameArctoa +
Taxon parentDicranaceae +
Taxon rankgenus +
VolumeVolume 27 +