"Vermilacinia rosei" is classified in the subgenus "Vermilacinia" in which it is distinguished from related species by its thallus divided into relatively few fan-shaped branches (less than 10)—widely expanded above a short narrow stalk-like base—and by its secondary metabolites of triterpenes, referred to as T1 and T2 by their Rf values on thin-layer chromatography plates; their formulas are C30H50O2 (T1) and C30H50OO (T2).