Phaeographis xanthonica

{{Short description|Species of lichen}}

{{Use dmy dates|date=December 2023}}

{{Speciesbox

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| taxon = Phaeographis xanthonica

| authority = Kalb & Matthes-Leicht (2009)

| range_map = {{Infobox mapframe|coord={{coord|22|20|S|44|45|W}}|zoom=3}}

| range_map_caption = Holotype site: Itatiaia, Brazil

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Phaeographis xanthonica is a species of corticolous (bark-dwelling), crustose lichen in the family Graphidaceae. Found in Brazil, it was formally described as a new species in 2009 by Klaus Kalb and M. Matthes-Leicht. The species epithet refers to the presence of the xanthone substance lichexanthone. The type specimen was collected in Itatiaia (Serra da Mantiqueira, Rio de Janeiro) at an altitude of {{convert|1750|m|ft|abbr=on}}. It has also been recorded from Costa Rica.

The thallus of Phaeographis xanthonica is smooth, {{lichengloss|matt}}, whitish-grey to whitish-beige, and lacks a prothallus. Its ascomata are {{lichengloss|lirelline}} in form, curved with tapered ends, and measure 0.5–4 mm long. The {{lichengloss|discs}} are black and bordered by a somewhat thick and split {{lichengloss|thalline margin}}. The {{lichengloss|ascospores}} have a transverse septum that divides it into four cells; their dimensions fall into the range 11–21 by 5–7 μm.