Arthoniaceae

Arthoniaceae is a family of fungi that primarily comprises lichens, although some non-lichenized species are also known. These fungi are typically found growing on bark, rocks, and soil. The family is characterized by its unique ascocarp, which is often apothecial but can also be lirelliform or even perithecial in some species. The ascocarp is usually sessile or stipitate and can be immersed, erumpent, or superficial. The excipulum, the outer layer of the ascocarp, is often poorly developed and can be difficult to distinguish from the surrounding thallus or substrate.

The asci of Arthoniaceae are typically unitunicate, cylindrical to clavate, and contain eight ascospores. The ascospores are usually muriform or distoseptate, meaning they are divided into multiple cells by both transverse and longitudinal septa. The paraphyses, sterile filaments that surround the asci, are often branched and anastomosing, forming a pseudopathecium.

The family Arthoniaceae is ecologically diverse, with species found in a wide range of habitats from tropical to temperate regions. Many species are pioneer colonizers, growing on exposed surfaces where few other organisms can survive. Some Arthoniaceae species are important components of their ecosystems, contributing to nutrient cycling and providing habitat for other organisms. The taxonomy of Arthoniaceae has been subject to revision due to advances in molecular phylogenetic studies, which have helped to clarify relationships within the family.