Polycoccum squamarioides
General description:
Conservation status:
Not evaluated by Woods & Coppins (2012), but listed as Nationally Rare.
Diagnostic description:
Look alikes:
Polycoccum deformans has also been described on Placopsis species, but was considered by Brackel & Berger (2010) to be gall-inducing and with ornamented rather than "nearly smooth" ascospores. It is considered a synonym of P. squamarioides pending further study. Roselliniopsis gelidaria also occurs on Placopsis species, but has four-spored asci and much broader ascospores.
Associations:
On thalli of Placopsis species, often causing galls.
Distribution:
Known from the Scottish Highlands, Cumbria, W. Wales and Dartmoor; apparently more or less coextensive with the host lichens.