Quaternaria quaternata  

Anamorph: visible externally as bright orange tendrils of conidia, the tendrils flattened due to compression of the host surface tissues. Conidia 12-21 x 1-1.2 µm, falcate, hyaline, aseptate.
Teleomorph stroma: immersed in bark, sometimes extensive, covered with the host periderm which is pushed up by groups of perithecia within the cortical parenchyma; with a strongly differentiated entostromatic zone under the periderm, limited ventrally by a well-marked necrotic zone which is interrupted by numerous extensions connecting the stroma to the wood; grey-brown entostroma developed weakly towards the necks of perithecia. Ostioles collectively emerging in groups of 2-6, most often in groups of four, often poorly differentiated, rounded, not strongly prominent, sometimes not clearly furrowed, 150-200 µm in diam. Peritheciain often confluent groups, spherical or frequently broader than tall, 400-600 diam. and 400-500 µm tall, the neck short. Asci p. sp. 60-95 x 8-11 µm, pedicel 90-160 µm, with a small apical ring that blues in iodine, 8-spored. Ascospores 12.5-19 x 3-4 (-4.5) µm, yellowish brown, allantoid, smooth and fairly thin-walled.

Description mostly adapted from Rappaz (1987).