Squamarina subcetrarioides comb. & stat. nov. (Stereocaulaceae), a separate species from the type species of Squamarina

Abstract The type species of Squamarina has two varieties, S. gypsacea var. gypsacea and S. gypsacea var. subcetrarioides. In this study, a phylogenetic and taxonomic analysis of these two varieties shows that S. var. subcetrarioides merits treatment as a species separate from S. gypsacea. Therefore, we raise this variety to species level as S. subcetrarioides (Zahlbr.) Y. Y. Zhang. Squamarina subcetrarioides is phylogenetically not closely related to S. gypsacea and differs from that species in the thallus forming rosettes when young, later becoming cracked and irregular in outline, and consisting of numerous small squamules.