Cladonia arbuscula subsp. arbuscula
A rare chemotype of Cladonia arbuscula with psoromic rather than fumarprotocetraric acid (and is thus Pd+ yellow rather than Pd+ rust-red). Molecular data for European populations are sparse, but a study focusing on North American samples (Piercey-Normore et al. 2010) did not support them as monophyletic. Pino-Bodas et al (2021) follow recent practise and treated Cladonia arbuscula as a single polymorphic species (see Cladonia arbuscula subsp. squarrosa, the dominant fumarprotocetraric acid containing morph).
There is only one confirmed British record, from coastal dunes in.E. Scotland (Angus). For the time being this morph is still being recorded separately in the BLS database.
Piercey-Normore, M.D., Ahti, T. & Goward, T. (2010). Phylogenetic and haplotype analyses of four segregates within Cladonia arbuscula s.l. Botany 88: 397–408.
Pino-Bodas, R., Sanderson, N., Cannon, P., Aptroot, A., Coppins, B., Orange, A. & Simkin, J. (2021). Lecanorales: Cladoniaceae, including the genera Cladonia, Pilophorus and Pycnothelia. Revisions of British and Irish Lichens 19: 1-45. Link
Text by Neil A Sanderson, based Pino-Bodas et al (2021)