Polycoccaceae is a family of lichenicolous (lichen-dwelling) fungi in the order Trypetheliales. The family was circumscribed in 2015 by Damien Ertz, Josef Hafellner, and Paul Diederich. Molecular phylogenetic analysis shows Polycoccaceae to have a sister relationship with the family Trypetheliaceae.

Species within the Polycoccaceae distinguish themselves from those in the Trypetheliaceae due to their non-lichenized, lichenicolous nature and typically smaller, 1-septate, brown ascospores. However, both share similarities, such as perithecioid ascomata, intertwined paraphysoids set within a hymenial gel matrix, and bitunicate asci. The primary morphological characteristics of the core group of the family, the type genus Polycoccum, are its thick-walled ascospores that are often distinctly ornamented.

Polycoccaceae comprises two genera: Clypeococcum with 12 species, and Polycoccum with 60 species. All members of this family are lichenicolous, with a collectively wide range of lichen hosts. Among the six families exclusively made up of lichenicolous fungi – including Abrothallaceae, Adelococcaceae, Sarcopyreniaceae, Obryzaceae, and Cyphobasidiaceae – Polycoccaceae is the most species-rich.

...