Scytinium intermedium?

[Neil Sanderson]

Another specimen from the gravel/crushed concrete biocrust habitat at Greenham Common, possible Scytinium intermedium. We had an inconclusive thread on small Scytinium species previously, so this was an interesting specimen to go through. It formed mounds of imbricate squamules with the lobes shallowly incised, not lacerate like Scytinium subtile/Scytinium tenuissimum. I managed to get a reasonable cross section, which suggested an medulla of disorganised hyphae (see https://www.afl-lichenologie.fr/Photos_ ... FLAT_S.htm for photos of cross-sections of several species). The wrinkling of Scytinium intermedium when dry is described as "upper surface weakly wrinkled" in LGBI. If this is it then it is a very fine wrinkling with the surface becoming rougher when dry.

Specimen still damp (and in a blue collecting box)

Damp specimen

Dried specimen

A closer view of dry squamules, finely roughened

Cross section, internal hyphae disorganised

Neil