Kiaeria glacialis I. Hagen 1915

Kiaeria glacialis is a large species that is found in late snowbeds and is similar to K. starkei, which is more slender and is commonly found on vertical rock surfaces. A form of K. starkei occasionally occurs in late snowbeds, but it has small, erect-spreading dark green leaves; K. falcata also occurs in late snowbeds, but can be distinguished in the field by its short, non-grooved capsules.

Plants robust, in loose tufts, mostly green to yellow, shiny. Stems 1-2(-4) cm. Leaves mostly falcate-secund, lanceolate, gradually subulate, 2-4.5 mm, margins distally 1 or 2-stratose; costa 50-60 µm wide at base; distal laminal cells mostly elongate (2-5:1), porose, 7-9 µm wide, smooth or weakly mammillose-roughened; basal laminal cells elongate, porose, alar cells strongly inflated and differentiated. Perichaetial leaves similar to the cauline. Perigonia sessile, located just below perichaetia. Capsule distinctly ribbed when dry, urn 1.3-2 mm. Spores 14-20 µm.

Plants rather robust, 4–10(–12) cm high, green to yellowish green or dull green, somewhat glossy, in compact tufts. Stems erect or ascending, often branched. Leaves 4–6 mm long, erect-patent, upper leaves falcate-secund, lanceolate, gradually narrowed from an ovate base to an subulate acumen toward the apex; margins plane, entire or serrulate near the apex; costa weak and slender, percurrent to shortly excurrent, papillose at the apex; upper cells elongate-rectangular, smooth, more or less porose; basal cells short-rectangular to rounded-rectangular; alar cells quadrate, inflated, forming distinctly auricles, dark brown, extending close to the costa. Autoicous. Androecia closely below the perichaetia. Perichaetial leaves large, sheathing at base. Setae ca. 1.5 cm long, straight, yellowish brown; capsules ovoid-cylindric, curved, strumose, furrowed when dry; exothecial cells elongate, somewhat thick-walled; opercula obliquely short-rostrate; annuli in 1 row of large cells, deciduous; peristome teeth reddish purple, divided 1/3– ½ down. Spores 12–20 µm in diameter, yellowish green, finely papillose.

Distribution: China, Russian Far East, Europe, and North America.

Habitat: on limestome, rarely on soil.

Dicranum glaciale Berggren, Acta Univ. Lund. 2(7): 19, figs. 1-9. 1866; D. arcticum Schimper; D. molle (Wilson) Lindberg

Paljakka-ahmansammal (Kiaeria glacialis) on lehtisammallaji kynsisammalten heimossa (Dicranaceae). Sitä esiintyy Maan pohjoispuoliskolla arktisilla alueilla ja vuoristoissa. Suomen alueella laji on pohjoinen tunturikasvi, jota esiintyy Kittilän, Sompion, Enontekiön ja Inarin Lapissa. Se on melko harvinainen ja elinvoimainen (LC).

Paljakka-ahmansammal kasvaa tunturipaljakalla keskipaljakan korkeudelle muun muassa lumenviipymillä, kuruissa, kivikoissa ja puroilla kostealla maalla tai kivipinnalla.

Laji muistuttaa kynsisammalia, sen voi sekoittaa turkkikynsisammaleen (Dicranum fuscescens) tai kivikynsisammaleen (Dicranum scoparium).

Kiaeria glacialis là một loài Rêu trong họ Dicranaceae. Loài này được (Berggr.) I. Hagen mô tả khoa học đầu tiên năm 1915.