Proposed 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. Please verify that Arthonia caesia is truely invalid and not just in restricted usage before committing.
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 (Link)
Unintended disagreements occur when a parent (B) is
thinned by swapping a child (E) to another part of the
taxonomic tree, resulting in existing IDs of the parent being interpreted
as disagreements with existing IDs of the swapped child.
Identification
ID 2 of taxon E will be an unintended disagreement with ID 1 of taxon B after the taxon swap
If thinning a parent results in more than 10 unintended disagreements, you
should split the parent after swapping the child to replace existing IDs
of the parent (B) with IDs that don't disagree.
