Plants of the Gila Wilderness

Aspicilia desertorum has gray green squamules usually with one, sometimes 2 grayish sunken lecoranine apothecia. The photobiont is a single celled green alga. This lichen looks very similar to Pertusaria saximontana, except that it has 4 spherical ascospores per ascus rather than two elliptic spores as in P. saximontana. The hymenenium is lightly pigmented and the hypothecium is hyaline. Aspicilias are usually found on rock, but we found this one growing on old rotting Alligator Juniper. The new name for Aspicilia desertorum is Circinaria desertorum, but I have retained Aspicilia as the genus because most of the references are still under that name, but also because I couldn't find an authority for the new name.
Thanks to Larry St. Clair for identifying this lichen!

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Aspicilia desertorum, photo Russ Kleinman & Karen Blisard, Pinos Altos Range, Pinos Altos, December 14, 2019

Aspicilia desertorum, photo Russ Kleinman & Karen Blisard, Pinos Altos Range, Pinos Altos, December 14, 2019

Aspicilia desertorum, photomicrograph of squamules and apothecia, photo Russ Kleinman & Karen Blisard, Pinos Altos Range, Pinos Altos, December 14, 2019

Aspicilia desertorum, photomicrograph of squamules and apothecia, photo Russ Kleinman & Karen Blisard, Pinos Altos Range, Pinos Altos, December 14, 2019

Aspicilia desertorum, photomicrograph of cross section of apothecium, photo Russ Kleinman & Karen Blisard, Pinos Altos Range, Pinos Altos, December 14, 2019

Aspicilia desertorum, photomicrograph of cross section of apothecium showing 4 spherical spores in ascus, photo Russ Kleinman & Karen Blisard, Pinos Altos Range, Pinos Altos, December 14, 2019