The
thallus, or the vegetative body of
Astrothelium, is , meaning it is covered by a protective . The
ascomata, which are the
fruiting bodies containing the reproductive spores, can appear in various forms such as simple, aggregated, or forming . These structures often differ in their composition and colour, and can be used as to distinguish between species. The ascomata can range from being immersed within the thallus to prominently displayed on the surface. The
ostioles, or small openings that allow the release of spores, can be located at the apex or eccentrically on the ascomata and may appear as either simple or fused structures.
Astrothelium is also notable for its ascomatal wall, which is made up of
hyphal cells and is typically carbonized. The wall features a , a term used to describe a tightly interwoven arrangement of cells. Within the , the tissue that houses the
asci (spore-producing structures), the cells are either clear or filled with oil droplets. The
ascospores, which are the sexual spores responsible for reproduction, are and
hyaline in appearance. They can also exhibit a variety of forms, including transversely
septate or , reflecting their segmented or multi-cellular nature. ==Species==