Karstenula microsporella ined.  

Stromata not conspicuously developed, visible externally as small bulges in the substratum surface which splits irregularly to expose black ectostromatic tissues.

Anamorph: conidiomata pycnidial, formed in small clusters within degraded bark tissue, the body 300-400 µm diam. and 200-250 µm tall, oblate, with narrow necks reaching the surface. Conidiomatal wall 30-40 µm thick, black, composed of several layers of thin-walled dark brown angular cells with the entire inner surface covered in a palisade of conidiogenous cells. Conidiophores not clearly defined, the conidiogenous cells formed in small clusters from small irregular thin-walled globose cells. Conidiogenous cells 10-13 x 7-10 µm, globose to pyriform, very thin-walled, sometimes proliferating percurrently and then sometimes with 1-2 inconspicuous annellations, subsequent conidia formed within a irregularly fringed collarette. Conidia 13.5-15.5 x 6-7.5 µm, cylindric-ellipsoidal or slightly ovoid, the apex and base rounded with no obvious scar, initially pale brown and verrucose but becoming conspicuously thick-walled, smooth and dark chestnut brown, with a ± median septum, without a gelatinous sheath or appendages.

Teleomorph: ascostromata formed in the lower and mid bark layers, strongly and irregularly raising the substratum surface and sometimes becoming erumpent through irregular cracks, composed of dark grey to black degraded host tissues mixed with fungal hyphae. Ascomata 500-700 µm diam and 450-550 µm tall, conical to oblate with a flattened base and broadly tapering upper part, the ostiole usually slightly papillate. Ascomatal wall distinct from the stromatal tissues, ca 20 µm thick, black, composed of several layers of irregular dark brown thin-walled angular cells to ca 12 µm diam., with a narrow inner layer of flattened hyaline tissue. Interascal tissue of thin-walled cellular pseudoparaphyses 2-2.5 µm diam., branched and anastomosing near the base and apex, not immersed in gel. Asci 210-240 x 14-16.5 µm, cylindrical, with a tapering stalk ca 30 µm in length, the base with clear evidence of crozier formation, the apex rounded, thick-walled and fissitunicate with a well-developed ocular chamber, 8-spored. Ascospores arranged uniseriately, hardly oblique, 23.5-26.5 x 9.5-11 µm, clavate-ellipsoidal, usually with 3 transverse septa, the primary septum ± median and more constricted, the upper part slightly wider than the lower, the middle two segments usually with a narrow longitudinal septum; minutely verrucose; occasional ascospores to 7-septate and then up to 36 µm in length; surrounded by a well-developed mucous sheath ca 2.5 µm thick.