Plants ca. 0.8--1.5 cm ´ 0.7--1.5 mm, ascending, brownish-purplish to brown. Stems 0.3--0.4 mm in diam., sparsely branching, transverse section with cortical and medullary cells; rhizoids numerous, colorless-pale brownish. Leaves succubous, imbricate, loosely complicate, transversely oblong, 0.7--0.9 ´ 0.8--1.2 mm, subequally 3-lobed, lobes ovate-triangular, sinus 0.2-0.3 of leaf length, apex acuminate to acute, margins entire or with scattered sharp teeth; cells rounded rectangular, marginal cells 20--25 m m, median cells 20--25 ´ 25--30 m m, basal cells 25--30 ´ 30--40 m m, cuticle weakly verruculose, strongly collenchymatous, trigones bulging; oil bodies 2--10 per cell, spherical to elliptical, 6--7 ´ 9--13 m m, finely papillose, grayish; underleaves absent. Specialized asexual reproduction by gemmae in masses at apices of juvenile leaves, reddish-brown, angular, 25--35 ´ 18--30 m m, 1--2 celled, smooth. Sexual condition dioicous. Male bracts similar to leaves, antheridia orange-yellow, antheridial stalk 1-seriate. Gynoecia terminal, female bracts larger than leaves, 2--5-lobed, lobes broadly ovate-triangular with entire margins. Perianth ovoid, plicate, mouth ciliated with teeth 2 cells long. Sporophyte unknown.

Peaty soil between rock clefts; 0--250 m; e, w, and n Greenland; Nun.

This species is superficially similar to Tritomaria scitula and T. quinquedentata, and is frequently associated with Aneura pinguis, Antheria juratzkana, Arnellia fennica, Blepharostoma trichophyllum subsp. brevirete, Cephalozia bicuspidata, C. pleniceps, Cephaloziella arctica, Cryptocolea imbricata, Gymnomitrion concinnatum, Jungermannia sphaerocarpa, Odontoschisma macounii, Plagiochila arctica, Prasanthus suecicus, Scapania gymnostomophila, and Tritomaria quinquedentata.