ABSTRACT The vitality of 64 lichen species (107 individual lichen thalli) growing under different light climates in an Araucaria forest in South Brazil was analyzed by chlorophyll fluorescence. Study sites were grouped according to their local light availability under full sunlight (about 2200 µmol m-2 s-1): 1 = low light, up to 20 µmol m-2 s-1; 2 = medium light, 20 to 100 µmol m-2 s-1; and 3 = high light, more than 100 µmol m-2 s-1. Maximum quantum yield of photosystem II, as shown by Fv/Fm of dark-adapted samples, was mainly between 0.3 and 0.7, with extremes of below 0.1 and up to 0.85. On average, yields were highest with low light availability (0.66). Groups 1 and 2 were not significantly different from each other, but groups 1 and 3, as well as groups 2 and 3 were. After dark adaptation, lichens were exposed to different light intensities by means of a chlorophyll fluorometer. The results show that low light-adapted lichens exhibit the highest sensitivity to excess light, as was also indicated by the data for non-photochemical quenching. Thus, shade-adapted lichens are obviously well protected from possible damage caused by excess light, which is important when exposed to sun flecks.

Heterodermia hypoleuca (Muhl.) Trev. e H. squamulosa (Degel.) W. Culb. são citadas como novas para o Brasil, e H. corallophora (Taylor) Skorepa, H. microphylla (Kuork.) Skorepa, H. trichophara (Kurok.) S. Eliasaro (nova combinação) são anexadas à flora conhecida do Estado do Rio Grande do Sul.

Heterodermia hypoleuca (Muhl.) Trev. and H. squamulosa (Degel.) W. Culb. are reported as new to Brasil, and H. corallophora (Taylor) Skorepa, H. microphylla (Kuork.) Skorepa, H.' trichophora (Kurok.) S. Eliasaro (new combination) are added to the known flora of Rio Grande do Sul state.

Foram identificadas 72 espécies de liquens coletados em Piraputanga, município de Aquidauana; 23 taxa são registradas pela primeira vez para o estado do Mato Grosso do Sul.

There are identified 72 species of lichens from Piraputanga, Aquidauana municipality; 23 taxa are reported for the first time for Mato Grosso do Sul State.

São caracterizados 77 gêneros de liquens do Morro Santana, Porto Alegre, RS, por meio de chaves analíticas, breves descrições e ilustrações; Anisomeridium Müll. Arg., Baeomyces Pers., Chrysothrix Mont, Laurera Reichemb., Maronea Massal., Pseudopyrenula Müll. Arg. e Ramalea Nyl. são acrescidos à flora liqüênica conhecida do Rio Grande do Sul.

There are caracterized 77 genera of lichens from Morro San tana, Porto Alegre, R S, with analytical keys, short descriptions and illustrations; Anisomeridium MuB. Arg , Baeomyces Pers., Chrysotkrix Mont., Laurera Reichemb., Maronea Massal., Pseudopyrenula Mull. Arg. and Ramalea Nyl. are added to the know flora of Rio Grande do Sul State.