Pyrenulaceae Pyrenula macrospora Growth type crustose Chemical results: K+ yellow, C-, KC-, P+ weak yellow, UV +/- weak yellow Most frequent Pyrenula species, can be locally common in South and West on shaded, smooth-baked trees. Mosiac-forming olive-brown to creamy yellow thallus with flecks of white pseudocyphellae and black prothallus. Black perithecia to 1mm, ostiole visible when mature. Spores brown, 3-septate, 25-35 x 8-12 µm. Microscope photograph below. Similar: P. chlorospila has smaller perithecia (photo below for comparison)

Microscope photograph

Pyrenula macrospora
Kimmeridge, Dorset and New Forest, Hants. December 2012, January 2013