Excerpts from Jim Conrad's
from the February 23, 2014 Newsletter issued from the Frio Canyon Nature Education Center in the valley of the Dry Frio River in northern Uvalde County, southwestern Texas, on the southern border of the Edwards Plateau, USA
DUST LICHEN MYSTERY
Exposed in the face of a cliff wall along the Dry Frio River a couple miles south of here there's a thin layer of conglomerate rock composed of pebbles and rounded stones cemented together with calcium-rich muck that hardened about 110 million years ago. A certain conspicuous lichen species I've not seen elsewhere occurs on this outcrop. The lichen presents itself as a pale greenish blotch with white fringes, but with no spore-producing, cuplike apothecia, as shown above.
After comparing the lichen with literally thousands of pictures on the Internet, finally I found a match. However, the picture was on a page entitled "Lichen Mysteries," and it bore no name. The photographer, Stephen Sharnoff, annotated it with the remark, "A species of Lepraria?"
The Internet abounds in pictures of unnamed lichens, but Stephen Sharnoff's picture really got my attention. First, of all the places in the world it could have been photographed, it was found in Lost Maples State Natural Area just a few miles north of us in Real County.
Second, the photographer, Stephen Sharnoff, is not just any photographer of unnamed lichens. He's coauthor of the monumental, prize winning Lichens of North America, and sole author of the new A Field Guide to California Lichens. If he can't name our lichen, then I certainly can't, and there's a fair chance that what we have here is something "new to science." I wrote to Stephen and he put me in contact with an expert of the genus Lepraria, to which this species probably belongs. Lepraria species sometimes are known as dust lichens.
So, this is pretty good. I'll let you know if something comes of our genuine Lichen Mystery. Stephen's Lichen Mystery page, with our unknown appearing fourth from the top, is at http://www.sharnoffphotos.com/lichensH/lichen_mysteries_9.html.