Two new species of <i>Placomaronea</i> (<i>Candelariaceae</i>: lichenized <i>Ascomycota</i>) in Peru, with a revision of secondary chemistry and cortical anatomy of <i>Placomaronea</i>, <i>Candelina</i> and <i>Candelariella</i>

Abstract Two new species, Placomaronea fruticosa and P. placoidea , are described. They were originally discovered in the southern Peruvian Andes at altitudes between 3000 and 4650 m. One specimen of P. fruticosa was subsequently also found among herbarium material collected in Argentina. Placomaronea fruticosa is terricolous in high altitude grasslands with rocky cliffs. It is characterized by its fruticose to subfruticose thallus, which is up to 8 mm tall and partially immersed in the substrate, its branches are bright to deep yellow, flattened and on the substrate surface their elongated apices resemble placodioid lobes of crustose species in the genus Candelina , whereas the cylindrical basal parts are pale beige to deep violet and mostly grow immersed in their substrate. The species has asci with over 20 ascospores in a 60–80 μm tall hymenium. Placomaronea placoidea is a saxicolous species, growing in rocky exposed areas. It is characterized by its tightly adnate, foliose, placodioid thallus with a bright to deep yellow upper surface. No fertile specimens were found. Both species newly described here are morphologically very similar to species of Candelina but are clearly distinguished by a cortex anatomy characteristic of Placomaronea. Cortex anatomy can thus be immensely useful to distinguish crustose and subfoliose genera in Candelariaceae , whereas secondary chemistry is shown to be quite uniform, with some chemotype variation of little taxonomic relevance. An updated ITS-only phylogeny of Candelariaceae is presented and compared with earlier phylogenies of the family. Several well-supported clades are identified, including Candelina , Placomaronea and Protocandelariella , but much of Candelaria and Candelariella s. lat. remain unresolved, and the relationships between the supported clades are not yet known. The limitations of currently available molecular data, primarily only ITS, are discussed, particularly in relation to the lack of support at species level, such as the two newly described species of Placomaronea. An updated key to currently accepted genera in Candelariaceae and all species of Placomaronea now known is provided. A Spanish version of this abstract is provided in Supplementary Material File S1 (available online).