Change based on synonymy in A Cumulative Checklist for the Lichen-forming, Lichenicolous and Allied Fungi of the Continental United States and Canada, Version 21, which in turn is based on Arup et al. (2013). Arup et al. have this to say about the genus Polycauliona:
Polycauliona is large genus consists of the smaller-sized foliose and fruticose species, formerly included in Xanthoria together with crustose as well as placodioid and leprose species. Even within the former Xanthoria candelaria group in a more narrow sense there are closely related species with crustose, placoid (P. stellata) or delicately foliose thallus (P. candelaria). In the ITS analysis there is no support for Polycauliona (PP = 0.4), but in the combined analysis there is full support. Within the genus there are also three fully supported subclades, which could be recognized as genera. One consists of only crustose members and two consist of lobate, crustose and subfruticose or foliose species. Recognizing them at the generic level does not make more sense than keeping them as one genus, the level of information does not increase considerably, and we therefore prefer one large genus with an obvious distribution centre, viz. southwestern North America.
So... I guess we should be happy they didn't split it up into even more genera?
Esslinger, T. L. (n.d.). A Cumulative Checklist for the Lichen-forming, Lichenicolous and Allied Fungi of the Continental United States and Canada, Version 21. Retrieved January 31, 2017, from https://www.ndsu.edu/pubweb/~esslinge/chcklst/chcklst7.htm (Vínculo)
@meurkc, here's another Arup change that will have some impact on you NZ folks (as well as those of us in North America). NZOR seems to have adopted Polycaulonia so I assume you guys will be ok with this, but just figured I'd check.
Los desacuerdos no intencionados ocurren cuando un grupo padre (B) se adelgaza al cambiar un grupo hijo (E) a otra parte del árbol taxonómico, provocando que las Identificaciones existentes del grupo padre sean interpretados como desacuerdos con las Identificaciones existentes del grupo hijo cambiado.
Identification
La ID 2 del taxón E será un desacuerdo no intencionado con la ID 1 del taxón B después del intercambio de ancestros
Si el adelgazamiento del grupo padre provoca más de 10 desacuerdos no intencionados, deberías dividir el grupo padre después de intercambiar el grupo hijo para substituir las identificaciones existentes del grupo padre (B) con identificaciones con las que no esté en desacuerdo,
@meurkc, here's another Arup change that will have some impact on you NZ folks (as well as those of us in North America). NZOR seems to have adopted Polycaulonia so I assume you guys will be ok with this, but just figured I'd check.