Astrothelium sipmanii
Astrothelium sipmanii is a species of corticolous lichen in the family Trypetheliaceae. It is found in Guyana.
Taxonomy
The lichens was formally described as a new species in 2016 by Dutch lichenologist André Aptroot. The type was collected by Harrie Sipman in the Upper Takutu District; here, in savannah forest, it was found growing on the smooth bark of trees. The species epithet acknowledges the collector of the type.Description
The lichen has a pale ochraceous-green thallus with a cortex; the thallus is surrounded by a thin black prothallus. The ascomata are pear-shaped, measuring 0.7–1.2 mm in diameter. The ascomatal walls are carbonized and up to about 80 μm thick; the ostioles are apically situated, black, and concave. Astrothelium sipmanii makes ellipsoid-shaped ascospores with 5 septa, and measure 100–150 by 35–40 μm. The hamathecium is with oil globules. No lichen products were detected in the collected specimens using thin-layer chromatography.Astrothelium curvisporum and A. pustulatum share some similar characteristics, but can be distinguished by differences in spore shape and septation.