Astrothelium megatropicum
Astrothelium megatropicum is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae. Found in Guyana, it was formally described as a new species in 2016 by Dutch lichenologist André Aptroot. The type specimen was collected by Harrie Sipman near Paramakatoi village (Potaro-Siparuni region) at an altitude of ; there, it was found growing on smooth tree bark. The lichen has a smooth and somewhat shiny, pale ochraceous-green thallus with a cortex and a thin (about 0.1 mm wide) black prothallus line. It covers areas of up to  in diameter. The presence of the lichen does not induce the formation of galls in the host plant. No lichen products were detected from collected specimens using thin-layer chromatography. The combination of characteristics of the lichen that distinguish it from others in Astrothelium are its uneven to  thallus; its confluent ascomata, which are  to prominent and exposed, with gently to steeply sloping sides; and the dimensions of its ascospores (100–120 by 30–35 μm). The spores, which have three septa and diamond-shaped cavities, are the longest 3-septate ascospores in the Trypetheliaceae. References

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