Tylophoron rufescens
Tylophoron rufescens is a species of lichen in the family Arthoniaceae, which was formally described in 2022 by André Aptroot. This corticolous crustose lichen was identified in the primary rainforests and on sandstone under overhanging cliffs of Mato Grosso, Brazil.
Taxonomy
Tylophoron rufescens was introduced to science in a study focusing on the lichen diversity of Brazil. The species name rufescens refers to the brown found on its .Description
The thallus of Tylophoron rufescens is crustose, discontinuous, and primarily whitish, covering up to 5 cm in diameter but is less than 0.1 mm thick. It often appears almost hyphal and can leave areas of bare bark exposed. The lichen hosts a photobiont.The ascomata are solitary and superficial, with dimensions of 0.4–0.7 mm in width and up to 0.8 mm in height. The displays a purplish brown mazaedium, surrounded by a whitish-gray margin. Ascospores are brown, 1-septate, ellipsoid, and measure 11–14.5 by 5.5–6.5 μm. They are darker around the septum and do not possess a gelatinous sheath.
Chemical spot tests on the thallus yielded a UV– and C+ reaction, suggesting the presence of gyrophoric and possibly diploschistesic acids. A distinct purplish pigment, likely isohypocrellin, reacts K+ but was not confirmed by thin-layer chromatography.