I am revising some old material again and I have these black semiglobular perithecia on bark of Thymus capitatus, about 0.5 mm in across mostly immersed in the woody bark. The ascospores are 5-7 septate (or having 6-8 compartmnts if that is easier), brownish-black, arranged imbricately or stacked diagonally in the ascus. The Asci are also interesting for having a broad funnel-shaped pore with a lonk neck when not fully mature and I think they are J-ve and bitunicate. Ascospores dextrinoid in KI (?). Paraphyses simple, threadlike, unspecialised, flexuous, 2-3um wide. 


Asci size (mean): 150 x 15 um
Ascospores (mean) : 18 x 9 um 


I am considering this to be Mycothyridium lividum, already reported from thyme but expert advice is welcomed. There is actually one thing that I am not seeing in my collection - the ascospores of (Myco)Thyridium lividum sometime have diagonal septae - not sure if this is characteristic for the species. Mattirolia sp. is another fungus to consider, (e.g. Mattirolia ohiensis = Teichospora ohiensis Ellis & Everh)...