SCHOENINGER, ROBIN1*, THOMAS H. NASH1, and JACK A. ELIX2. 1Lichen Herbarium, Department of Plant Biology, Arizona State University, P.O. Box 871601, Tempe, AZ, 85287-1601, USA; 2Australian National University, Chemistry Department, Canberra, A.C.T. 0200, Australia. - The chemistry of Acarospora subgenus Xanthothallia (Lichenized Ascomycete, Lecanorales) in Southwestern North America.
Acarospora is a poorly known crustose lichen genus commonly
found in the southwestern United States and Mexico. The genus is
commonly divided into two subgenera: A. subgen.
Xanthothallia and A. subgen. Phaeothallia (or
A. subgen. Acarospora). These subgenera are generally
distinguished by chemistry. Members of the subgen.
Xanthothallia contain the intense yellow pigment rhizocarpic
acid, thus exhibiting a yellow color, whereas members of the subgenus
Phaeothallia lack rhizocarpic acid and are usually brown. The
use of secondary products as taxonomic characters in Lichenology has
gained popularity over the last 30 years. As the initial stage of a
thorough study of this subgenus in the greater Sonoran Desert, the
secondary products of over 800 specimens were analyzed using thin
layer chromatography (TLC). One new secondary product was found
(xanthothallic acid), and four secondary products were recognized for
the first time in this subgenus (ovoic acid, 4-0-demethylnotatic acid,
hyproprotocetraric acid, and eumitrin A1).
Key words: Acarospora, chemistry, xanthothallic acid