Anatomy and taxonomy of cetrarioid lichens

Abstract: The anatomy of the cetrarioid lichens (Parmeliaceae) has been studied, and the taxonomy revised. Special attention has been paid to reproductive structures, in particular the asci and pycnoconidia. Two types of asci are recognized. The Cetraria type is narrowly clavate, bears an amyloid ring structure in the tholus, and has a small axial body. The Lecanora type, specifically the Melanelia form, is characterized by its broad clavate form and broad axial body. Five main types of pycnoconidia are noted; bacillariform, bifusiform, citriform, filiform and sublageniform. Six new genera are described: Arctocetraria Kärnefelt & Thell, Cetrariella Kärnefelt & Thell, Flavocetraria Kärnefelt & Thell, Kaernefeltia Thell & Goward, Nimisia Kärnefelt & Thell and Tuckneraria Randlane & Thell. Seven new species are presented: Allocetraria flavonigrescens Thell & Randlane, A. sinensis Gao, Cetraria peruviana Kärnefelt & Thell, Cetrariopsis laii Thell & Randlane, Cetreliopsis papuae Randlane & Saag, Nimisia fuegiae Kärnefelt & Thell and Tuckneraria ahtii Randlane & Saag. Also described are two subspecies, Cetreliopsis rhytidocarpa ssp. langtangii and Flavocetraria nivalis ssp. montana. The four species earlier included in the genus Coelocaulon Link. have now been transferred to Cetraria Ach. Several additional taxa have changed taxonomic levels, become a new genus possession, or have been synonymized with other taxa.