| Spores elongate, 2- or more-septate. | ||
| Spore cells cylindrical, colourless | 1. | *Pleurotrema Müll.-Arg. |
| Spore cells globose-lentiform. | ||
| Spores colourless | 2. | *Plagiotrema Müll.-Arg. |
| Spores brown | 3. | *Parathelium Müll.-Arg. |
| Spores muriform. | ||
| Spores colourless | 4. | *Campylothelium Müll.-Arg. |
| Spores brown | 5. | *Pleurothelium Müll.-Arg. |
IX. Trypetheliaceae
This and the following two families are distinguished by the pseudostroma or compound fruit, a character rare among lichens, though the true stroma is frequent in Pyrenomycetes in such genera as Dothidea, Valsa, etc. The genera are crustaceous and corticolous and occur with few exceptions in tropical or subtropical regions, mostly in the Western Hemisphere. Several grow on officinal bark (Cinchona, etc.). Algal cells are Trentepohlia. As in many tropical lichens, the spores are large. The genera are based chiefly on spore characters, on septation, and on the form of the spore cells:
| Spore cells cylindrical or cuboid. | ||
| Spores colourless, elongate, multi-septate | 1. | *Tomasiella Müll.-Arg. |
| Spores colourless, muriform | 2. | *Laurera Rehb. |
| Spores brown, muriform | 3. | *Bottaria Massal. |
| Spore cells globose-lentiform. | ||
| Spores colourless, elongate, multi-septate | 4. | *Trypethelium Spreng. |
| Spores brown, elongate, multi-septate | 5. | Melanotheca Müll.-Arg. |
X. Astrotheliaceae
The perithecia are either upright or inclined, and occur usually in radiate groups. They are free or united in a stroma, and the elongate ostioles open separately or coalesce in a common canal. The genera are all crustaceous, with Trentepohlia gonidia. They are tropical or subtropical, mostly in the Western Hemisphere; but species of Parmentaria and Astrothelium have been recorded also from Australia.
The spores are all many-celled and the form of their cells is a generic character:
| Spores elongate, multi-septate. | ||
| Spore cells cylindrical | 1. | *Lithothelium Müll.-Arg. |
| Spore cells globose-lentiform. | ||
| Spores colourless | 2. | *Astrothelium Trev. |
| Spores brown | 3. | *Pyrenastrum Eschw. |
| Spores muriform. | ||
| Spores colourless | 4. | *Heufleria Trev. |
| Spores brown | 5. | *Parmentaria Fée. |