Santa Rosa Plateau Rock Lichens
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Rock Lichens On The Santa Rosa Plateau
© W.P. Armstrong, 24 November 2007

Basalt Columns Along Edge Of Mesa de Burro

Covered with dense crustose lichens, incl. Acarospora & Caloplaca

Polygonal basalt columns at the edge of Mesa de Burro. These formations are similar to basalt columns at Devil's Postpile National Monument in the Sierra Nevada.

  Devil's Postpile National Monument  

Bright Yellow Acarospora On Basalt (cf. A. socialis)

This appears to be Acarospora socialis, a common crustose rock lichen in San Diego County to the south of the Santa Rosa Plateau. Individual sections (areoles) are attached to the substrate by short stalks (stipes). Many of them also contain a brown apothecium bearing numerous minute spores in saclike asci. The small red ascus is from a different species (Caloplaca). Photographed through a B & L dissecting microscope with Sony V-3.

  Acarospora socialis in San Diego County  

Bright Red Caloplaca On Basalt (cf. C. saxicola & C. ignea)

The deep red crustose lichen is Caloplaca ignea. There are at least two species of Caloplaca on this boulder, including C. saxicola.

Two species of firedot lichens (Caloplaca). Left: This orange-red lichen keys out very close to C. saxicola. It is reported from the Santa Rosa Plateau. Right: This deep red species keys out to Caloplaca ignea. The thallus has the characteristic deep red color and the marginal lobes are slightly flattened. The largest apothecia are 1.0 mm in diameter. See the following images of C. ignea.

This deep red lichen appears to be Caloplaca ignea.

This appears to be Caloplaca ignea. The ID is based on the deep red color of the thallus and slightly flattened marginal lobes. C. saxicola is very similar and is also reported on the Santa Rosa Plateau. Photographed through B & L dissecting microscope with Sony V-3.

Flame firedot lichen (Caloplaca ignea). The thallus has a deep red color and the marginal lobes are slightly flattened. C. saxicola is very similar and is also reported on the Santa Rosa Plateau. The largest apothecia are 1.0 mm in diameter. Photographed with Sony T-10 set on magnifier view.