Note. The bands of dark granular material mentioned as a distinguishing character of Pyrenula plittii are in this ascospore type only a development state (postmature ascospores), visible also in some other species (Aptroot 2012).
Reference
Aptroot, A. (2012) A world key to the species of Anthracothecium and Pyrenula. The Lichenologist44(1): 5-53.