Thysanothecium scutellatum

Detailed description

Primary thallus squamulose, or ± nodular-papiliate, squamules ± dorsiventral, scattered to ± densely packed, imbricate, forming a spreading, diffract- areolate crust, minute, 0.05-0.5(-1.0) mm diam., margins crenate, becoming lobulate, convex and ± closely attached to substrate, to ascending, ± imbricate, whitish or pale greenish to greenish-yellow above, tinged brownish at apices, white below, often clothing base of pseudopodetia to 5 mm, on charred or decorticated wood. Pseudopodetia arising from margins or apices of primary squamules, at first simple, terete and uniformly corticate, at maturity fissured, grooved, ± canaliculate or partly hollow, formed of horny, cartilaginous nerve- like strands between which corticate granules and medullary hyphae are exposed, 1-2 mm wide at base, flaring to 2-6 mm wide at apices, 0.1-10(-15) mm tall. Cortex yellowish-green to brownish, distinctly grooved-striate, discontinuous, cartilaginous strands corticate, glossy, spaces between filled with corticate granules and medullary hyphae. Apothecia terminal often also subterminal on secondary branches, disc ± plane, rotund at first, becoming irregular- undulate, fan-shaped or deeply crenulate-lacerate, margins entire at first, becoming sinuous, crenate, persistent, distinctly raised, concolorous with thallus or paler, surface of disc smooth or very minutely scabrid, pale yellowish- green to pinkish-brown, not or rarely minutely white-pruinose. Ascospores ellipsoid, straight or slightly curved, 5-8 × 3 µm. Pycnidia marginal on primary thallus, black, cylindrical to bottle-shaped, with an apical gaping ostiole 0.05-0.08 mm wide. Conidia not seen.

Chemistry: Cortex and medulla K−, C−, KC−, Pd−; containing divaricatic, nordivaricatic (tr.), stenosporic (tr.) and usnic acids.