Astrothelium vulcanum
Astrothelium vulcanum is a species of corticolous (bark-dwelling) lichen in the family Trypetheliaceae. Found in Guyana, it was formally described as a new species in 2016 by André Aptroot. The type specimen was collected from the Kuyuwini Landing (Rupununi) at an elevation of ; here, in a savannah forest, it was found growing on the smooth bark of trees. The lichen has a smooth, somewhat shiny thallus surrounded by a thin black prothallus, and covering areas up to  in diameter. Its ascospores are spindle-shaped (fusiform) with rounded edges, with three septa and dimensions of 20–25 by 6.5–7.5 µm. Astrothelium vulcanum contains lichexanthone, a lichen product that causes the thallus to fluoresce when lit with a long-wavelength UV light. References

vulcanum
Lichen species
Lichens described in 2016
Lichens of Guyana
Taxa named by André Aptroot