A key to the corticolous microfoliose, foliose and related crustose lichens from Rondônia, Brazil, with the description of four new species

Abstract A key is given to the foliose and squamulose lichens known so far from Rondônia, including also corticolous crustose lichens with a chlorococcoid alga. The foliicolousLecanoralesfound are also listed. The following four new corticolousLecanoralesare described from Rondônia:Calopadia granulosawith a granular, corticate thallus and ascospores 1 per ascus, 33–38×10·5–13·0 µm;Crustospathula amazonicawith irregularly capitate to nearly globose,c.0·2–0·4 mm diam. soralia on cartilaginous stalks;Flavoparmelia plicatawith a thallus containing usnic and protocetraric acids, with laminal, irregular, globose to cylindrical isidia which are often easily abraded and showing the whitish medulla, but not sorediate or postulate;Physcidia striatawith ascending squamules, without hypothallus, often with laminal isidia in defined areas towards lobe tips of some, usually sterile lobes, and often with biatorine apothecia with ascospores simple to 1-septate, (6·2–)7·5–10·0×(2·5–)3·0–3·5 µm. In the whole lichen flora of the lowland rainforest region of Rondônia, the following traits can be discerned: foliose lichens amount to only 17 species (2·7% of nearly 600), 33 (5·5%) are squamulose, while the vast majority (91·8%) are crustose. Cyanobacteria are present in only 6 (1%) species. A chlorococcoid alga present inc. 100 (16%), 12 of which (2%) have a myrmecioid alga. The remainder of the species, a staggering 83%, have trentepohlioid alga, including 6 (1%) withPhycopeltis. In neotropical lowland rainforest, the vast majority of the lichens are crustose and contain a trentepohlioid alga, and theArthoniales,Graphidaceaeand pyrenocarpous lichens are the main groups, each accounting for roughly a quarter of the lichen biodiversity.