Molecular phylogenetics
Molecular phylogenetics have shown that "C. cirrhata" forms a monophyletic clade with the remaining two species of "Collybia". Because "C. cirrhata" is the only one of the three "Collybia" species lacking sclerotia, it has been suggested that this character trait is an "anapomorphy"—that is, unique to a single, terminal species within a clade.