Hi,

Found this fungus on decorticated angiosperm wood (unknown) in southeast Brazil (São Paulo state). I think it could be a penzigioid Xylaria, but I'm not sure.

It has pulvinate to somewhat applanate stromata, not carbonaceous but lately leathery, reaching 1.5 cm length x 0.6 cm width x 1 mm height, with perithecia immersed in a white sclerotial tissue. Young stromata, pulvinate and light brown, becoming more applanate and darker (black at naked eye) with age.
Perithecia immersed, most globose to subglobose or elliptic, 230-320 high x 190-280 width, perithecia wall 13-15 µm thick, opening through the stromatal surface through ostioles; the ostiole has thick and blackened cells forming a clypeus.
Asci are clavate to subclavate, apical apparatus blueing very weakly, even after KOH pre-treatment, 55-90 x 4.7-5.3
Ascospores are unicellular, light brown, most sub-cylindrical with rounded ends, 5-6.5 x 2.3-3.0, inconspicuous germ slit (?).
I was unable to see any kind of germ slit, but after KOH treatment in MLZ mounting almost all spores assumed a "common bean-shape" (or more technically, become reniform), which I assumed be due to a thinning of the spore wall (an inconspicuous germ slit??).
Any help will be welcome!
Dartanha