Hi all,
I collected this saxicolous brown crust from Modoc County recently. I first thought it might be Rhizocarpon bolanderi, but the specimen exam seems to point to one of the Lecidea species and I tentatively keyed it to the L. atrobrunnea complex, possibly L. protabacina due to the nice P and K reactions of the thallus. Would love confirmation of the genus anyway, if possible - perhaps a species ID would require TLC? Thanks! Photos attached and my specimen description is below:
Nodular brown crust growing on boulder near parking area. The squamules/areoles vary from dispersed amongst a black prothallus to mounded and overlapping. They measure 0.5-1.0 mm in diameter and have a lightly pruinose rim in some areas. Occasional 1.0-mm black convex apothecia are found on the surface of the thallus.
Cross-sections through the apothecia reveal lecideine architecture with a dark epihymenium, a blue hymenium and eight simple, small, hyaline spores per ascus measuring 8 x 4 microns. The hypothecium appears to be grayish. No polarizable crystals are seen within the apothecia. A narrow pale exciple with a dark rim is noted.
Thallus cross-sections show a green algal photobiont. Spot tests performed on thallus cross-sections show a rather strong P plus orange reaction and a faint K plus yellow test. C negative.
