I was intrigued by this net-like growth of brown fungus on the upper surface of a Protoparmeliopsis specimen I collected recently (kindly identified to genus by Jason Dart). It consists of dematiaceous hyphae that are 2 microns in width and have numerous septae and side branches. Since I didn't find any fruiting bodies, I assume it might be impossible to ID, but thought I would post it here to see if anyone had encountered this before?
I've attached four photos of the fungus. The host lichen is posted at iNat here:
https://www.inaturalist.org/observations/170773560
Thanks!
Ken Schneider
San Francisco, CA