Calomnion complanatum

Asexual propagules absent. Mats on tree fern trunks, yellowish to orange-green. Stems 6–12 mm long, orange-brown at base, otherwise yellowish, with yellow to red-brown rhizoids restricted to very base. Leaves dimorphic with 2 lateral ranks differing from ventral rank in length and shape, flat, scarcely altered when dry; costa subpercurrent to long-excurrent; apex acute to acuminate, often mucronate; margins entire or irregularly denticulate, flat; laminal cells polygonal to quadrate, isodiametric, similar size throughout, 5–13 μm long, 5–11 μm wide; lateral leaves elliptic to ovate-elliptic, 0.7–1.1 mm long, 0.3–0.4 mm wide, perichaetial leaves longer; ventral leaves broadly elliptic or orbicular, 0.4–0.5 mm long, 0.4–0.5 mm long wide. Setae 2–4.5 (–6) mm long, yellow, smooth. Capsules ellipsoid or cylindric, straight, 0.8–1.5 mm long. Operculum oblique-rostrate, c. 0.6 mm long.