The lichen genus Buellia de Not. in the greater Sonoran Desert Region: saxicolous species with one-septate ascospores (original) (raw)

Thirty-one saxicolous species of Buellia s.l. with one-septate ascospores were examined from the Greater Sonoran Desert Region. They are distinguished by thallus morphology, exciple anatomy, spore ultrastructure, secondary chemistry, ecology and distribution. As a result, seven new species are described. Other species are reported from the region for the first time and the synonymy of several taxa is resolved. All species are traditionally included within the Physciaceae. Recent molecular evidence suggests that calicioid lichens are closely related to Buellia s.l. A comparison confirms that spore wall ultrastructure is identical in both groups. Iodine staining of the ascus in the light microscope corresponds well with the ascus ultrastructure. This Bacidia-type ascus is variable but common to all species. The prototunicate asci of calicioid Physciaceae may have evolved by reduction from this type. Spore ontogeny of Buellia s.l. is a highly dynamic process. Four stages can be disting...