Leptorhaphis tremulae  

Mycelium immersed in the substratum, composed of colourless, smooth, thin-walled hyphae, less than 3 µm diam., constricted at the septa, not associated with algae.
Anamorph: not known.
Teleomorph: ascomata perithecia, 100-150 (-250 µm) diam., 55-75 µm tall, ± round in outline, black, matt, smooth, scattered or in small clusters, initially immersed in the substratum, becoming ± superficial; hemispherical to applanate, dimidiate, the ostiole central. Upper wall dark-brown to greenish black, ca 10-15 µm thick, sometimes extending in a basal fringe to ca 55 µm broad, composed of bark material intermixed with greenish black to dark brown epidermoid tissue. Exciple not differentiated. Interascal tissue of irregular pseudoparaphyses 2-2.5 µm diam. ± breaking down at maturity. Hymenial gel not changing colour in iodine. Asci 40-66 x 18-25 µm, ovoid-clavate, to ± cylindrical, sessile or short-stalked, with two functional wall layers, with a broad truncate internal apical beak, 8- to 16-spored. Ascospores arranged in 1-3 fascicles, 13-25.5 x 3-4.5 µm, fusiform, arcuate with rounded apices,  1 -septate, smooth, thin-walled, hyaline, without an epispore or gelatinous sheath.