Xylaria crozonensis  

Anamorph: not known.

Teleomorph: stromata 5-14 mm diam. and 1.5-3.5 mm thick, discoid to pulvinate, roughly circular in outline, ± flat-topped, sometimes somewhat incurled, with a short ± central stalk, dark purplish brown to black, with minutely papillate ostioles visible over the upper surface, the flesh white, composed of fungal tissue with occasional dead plant cells incorporated into the structure. Ascomata arranged in a single layer, 600-850 µm diam., ± globose to ovoid. Peridium composed of an outer layer of dark brown thick-walled flattened textura intricata, and an inner layer of almost hyaline flattened thin-walled cells. Interascal tissue of simple unbranched paraphyses 2-2.5 µm diam. Asci 115-140 x 10.5-13 (-16) µm, narrowly cylindrical, occasionally broader in the mid section due to the arrangement of the ascospores, rather thin-walled, with a long tapering stalk, a rounded apex and an apical ring 2.5-3 µm diam. and ca 0.5 µm thick that blues in iodine, 8-spored. Ascospores 14-16.5 x 7.5-8.5 µm, broadly fusiform-ellipsoidal with one end frequently apiculate, hardly inaequilateral, aseptate, initially hyaline and 1- to 2-guttulate, becoming dark brown and ± opaque, with an indistinct germ slit extending between half and two thirds of the length of the spore, without a gelatinous sheath or appendages.

Map of known distribution in Great Britain and Ireland.