PECULIARITIES OF THE AUSTRALASIAN LICHEN FLORA: ACCESSORY METABOLITES, CHEMICAL AND HYBRID STRAINS

Abstract

  The taxonomic status of a variety of chemically characterised lichen populations is considered. In Parmelia subg. Xanthoparmelia where chemistry is a very significant character in the delimitation of species, the recognition of taxonomically insignificant accessory metabolites is of considerable importance. A group of aliphatic acids and amino-acid derivatives are demonstrated to fall into this category. On the other hand taxa containing different phenolic metabolites, even when these may be biosequential in nature, can usually be distinguished morphologically.

  The New Zealand endemic, Parmelia testacea, has been shown to occur in four chemical races. Individuals comprising all the possible combinations of these races have been detected attesting to the interchange or combination of genetic material between them. Chemical combinations have also been detected in the Australian (Queensland) species Ramalina leoidea while Hypogymnia lugubris occasionally produces the depside olivetoric acid in place of (or together with) the isostructural depsidone, physodic acid.