Revision of the genus Psoroma Michaux (Pannariaceae) in Argentina.

PASSO, A., S. CALVELO, S. Y E. STOCKER.

Halifax, Nova Scotia, Canadá

Congreso; . Lichen Symposium, IV International Symbiosis Society Congress.; 2003

Saint Mary's University, Halifax, Canada

The genus Psoroma Michaux (Pannariaceae) sensu lato consists of squamulose, foliose to fruticose species. In the past years, it has undergone some changes in the species concept, most of them suggested by Jørgensen (2001). Foliose species, like Ps. sphinctrinum (Mont.) Nyl., Ps. leprolumum (Nyl.) Räsänen and Ps. microphyllizans are now regarded as “green” representatives of the genus Pannaria Delise. In the present investigation, the taxonomy, morphology, anatomy and chemistry of selected foliose species have been studied. The chemistry of the lichen substances was analyzed by TLC and HPLC. Psoroma patagonicum Malme, Ps. allorhizum Nyl. (from New Zealand) and Ps. athroophyllum Stirton were found to show a close relationship to the P. sphinctrina group, defined by Jorgensen. The above species mentioned have related morphology and anatomy, with a well defined upper cortex and a layer of dead hyphae. The chemical profile is composed by two rare depsidones, vicanicin (or isovicanicin) and leprolomin (plus allorhizin, sometimes also present in Ps. allorhizum). New characters will be specified for the three species of the Pannaria sphinctrina group, which are actually not easy to identify. In this study, we present the preliminary results of a long term revision of the genus Psoroma.