Otidea platyspora is a fungus forming brown, large clustered apothecia. Due to its almost unique large spores, O. platyspora clearly distinguishable from other Otidea species.

This ectomycorrhizal species has large conspicuous apothecia usually growing in big clusters, but it is very scarcely recorded. It is associated with old deciduous tree stands with continuity, especially oaks, in castle parks and old forests. It is a rare species in all the countries where it has been recorded so far, and many of the reports are older than 25 years. This species might be in regression due to the exclusiveness of its habitat.  Habitat fragmentation and loss can considerably diminish the few localities known today.

Preliminary global (and European) red-list assessment: EN C2a(i) (< 250 mature individuals in largest subpopulation, estimated continuing decline).

The species is mainly present in Europe, but a locality is known in Azerbaiyán and it is likely to be more widespread in Asia. In Europe, it is present in Central and North Europe, but it is rare and localized all over its distribution. The stronghold of the populations of this species is in Sweden, where ca. localities are known.

Otidea platyspora has up to date been cited in around 30 localities in Europe, of which 15 are in Sweden. Part of this records are older than 25 years. We estimate that O. platyspora might be present in 150 localities in Europe. Populations of O. platyspora are restricted to small sites with ancient trees and thus contain few individuals. Some of its populations have disappeared or are threatened by destruction.

This species is associated with old Quercus trees, but it is possibly associated with other deciduous trees. Most of the sites consist of old castle gardens and parks, occurring in rather opened stands of trees on grassy ground

Suppression of old host trees can negatively affect populations of O. platyspora. Most of the populations are restricted to reduced park or gardens, and host very few individuals. Habitat fragmentation is another threat. Whereas a few sites have already disappeared, a few more sites are in the vicinity of urban areas and might be subjected to additional damage in the future.

Protection of the known sites is essential, ensuring that their management is maintained and potential old host trees will be available in the future.

Nannfeldt JA. 1966. On Otidea caligata, O. indivisa and O. platyspora (Discomycetes, Operculatae). Annales Botanici Fennici 3: 309–318.
Olariaga, I.; Van Vooren, N.;  Carbone, M. & Hansen, K. 2015 (in press). A monograph of Otidea (Pyronemataceae, Pezizomycetes). Persoonia 33.
Van Vooren N, Armada F. 2011. Redécouverte d´Otidea platyspora Nannf. (Ascomycota, Pezizales) en France. Bulletin mycologique et botanique Dauphiné-Savoie 203: 57–62.