Pyxine jolyana

The thallus (lichen body) is tightly attached to its substrate and usually forms a roughly circular rosette up to about 7 cm (2.8 in) across. It is brownish gray and divided into narrow lobes (laciniae) about 0.5–1.0 mm wide, with rounded to slightly squared-off tips. The upper surface is mostly smooth and lacks isidia or other solid vegetative outgrowths, but soralia are common and tend to sit just inside the lobe margins; the soredia are powdery to slightly granular. The lower surface is black (often a bit paler toward the lobe tips) and bears many simple (unbranched) rhizines of similar color, reaching about 0.7 mm long.^[1]

Internally, the medulla is variably colored: it may be cream to pale yellow to salmon in upper parts, and sulphur-yellow beneath soralia, while a thin lower layer can remain white. In older central areas a reddish-purple pigment reaction may appear with potassium hydroxide solution (the K test). Pycnidia are rare and occur on the upper surface; the conidia are small and flask-shaped. Chemically, the cortex contains lichexanthone (giving a yellow fluorescence under ultraviolet light), while the medulla contains norstictic acid along with triterpenes and pigments; the norstictic acid can be unevenly distributed, so spot tests from the lobe tips alone may miss it.^[1]

This species was originally known from São Paulo State in southeastern Brazil, with records from coastal and near-coastal localities (including Peruíbe, Ubatuba, and São Luís do Paraitinga). It occurs from near sea level (about 1–5 m) up to at least 915 m (3,000 ft) elevation.^[1] It has since been recorded from Minas Gerais.^[3][4]

Pyxine jolyana grows either on rock (saxicolous) or on bark and woody surfaces (corticolous). Collections include thalli on coastal rocks, on palm stipes near a river mouth in windy, sun-exposed conditions, and on twigs and tree trunks at the edges of forest (including restinga vegetation near the ocean and shaded forest margins).^[1]