# Gloeoheppiaceae

Gloeoheppiaceae is a family of ascomycete fungi in the order Lichinales. The family contains ten species distributed amongst three genera. Most species are lichenised with cyanobacteria. Species in this family are mostly found in desert areas. Modern molecular phylogenetics analysis casts doubt on the phylogenetic validity of the family, suggesting a more appropriate placement of its species in the family Lichinaceae.

## Taxonomy

The family was circumscribed in 1995 by the German lichenologist Aino Henssen. Her research corroborated the findings of Marton & Galun (1981) and provided additional support for the distinction between the genera Gloeoheppia and Heppia, initially suggested by Vilmos Kőfaragó-Gyelnik in 1935. Henssen observed that the unique paraphyses of Heppia, with a base comprising short cells, align closely with characteristics found in genera of the family Coccocarpiaceae. This is further evidenced by the presence of thick ascogonia (female reproductive structures), trichogynes (long, slender organs in female gametangia), and thallus hyphae, as well as by its attachment to substrates via single rhizoidal hyphae, a feature common to members of the families Collemataceae or Placynthiaceae. Conversely, in Gloeoheppia, the development of apothecia (fruiting bodies) and the overall structure of the thallus bear a closer resemblance to those found in the family Lichinaceae, marking a distinct differentiation from Heppia.
In molecular phylogenetics analysis published in 2021, Díaz-Escandón and colleagues show that the Gloeoheppiaceae was recovered in a highly supported clade with Lichina and Lichinella (both genera members of the family Lichinaceae), and that in their analysis the three families of Lichinales recognized in the current literature are not recovered. They suggest that "support in particular for the family Gloeoheppiaceae ... does not appear to be forthcoming".

## Description

The Gloeoheppiaceae consists of lichen-forming fungi with a squamulose to peltate (shield-like) thallus, which is homoiomerous, meaning its internal structure is uniform throughout. The family's photobiont (photosynthetic partner) is cyanobacterial, typically of the chroococcoid type. As for reproductive structures, the ascomata (fruiting bodies) are apotheciate and lecanorine, meaning they are disc-like and often sunken or closely attached to the thallus. The hamathecium, the tissue layer containing fertile parts of the ascomata, comprises paraphyses that are either unbranched or branched and can be amyloid (staining with iodine) or non-amyloid. The asci, which are the spore-bearing cells, are prototunicate and non-amyloid, indicating a simple, undifferentiated wall. The ascospores are straightforward in form: simple, ellipsoid, hyaline (translucent), and non-amyloid. For asexual reproduction, Gloeoheppiaceae have conidiomata (structures producing asexual spores) known as pycnidia, with non-septate, bacilliform (rod-shaped), hyaline conidia. No secondary metabolites have been identified in this family.

## Genera and species

As of December 2023, Species Fungorum (in the Catalogue of Life) accept three genera and ten species in the family Gloeoheppiaceae:
* Gloeoheppia Gyeln. (1935)
   * Gloeoheppia erosa
   * Gloeoheppia polyspora
   * Gloeoheppia rugosa
   * Gloeoheppia squamulosa
   * Gloeoheppia turgida
* Gudelia Henssen (1995)
   * Gudelia mexicana
* Pseudopeltula Henssen (1995)
   * Pseudopeltula dicyanophora
   * Pseudopeltula heppioides
   * Pseudopeltula myriocarpa
   * Pseudopeltula necrocorticata

## Habitat and distribution

Members of the Gloeoheppiaceae are either terricolous (ground-dwelling) or saxicolous (rock-dwelling), and tend to prefer growing on substrates that are calciferous. They are generally found in dry subtropical areas or regions with a Mediterranean climate.