Usnea grandisora Truong & P.Clerc The Bryologist114: 490 (2011).
Type: Ecuador. Galápagos, Isla Santa Cruz, above Mina Granillo Rojo, on the N-side of the island, 0°37.0'7.5''S, 90°21.0'55.5''W, 607 m alt., transition zone with Bursera graveolens, Psidium galapageium, Scalesia pedunculata and Opuntia echios, slope 10°N, on Scalesia branches, 7-Aug-2008, Truong 1122 [holotype in CDS (39433); isotype in G]. %C/M/A: 11/20.5/38. Chemistry: usnic, salazinic, galbinic and norstictic acid.
Short Descriprion: A detailed description of U. grandisora is available in Truong et al. (2011); this species is characterized by an erect-shrubby thallus with an orange subcortical pigmentation, branches irregularly covered in fibrils and isidiofibrils, large and excavate soralia, which, on the terminal branches, become crowded. The species has a relatively thickcortex that is shiny in section, and a dense medulla.
Chemistry. Medulla with salazinic, and norstictic acid [P+ orange yellow, K+ yellow turning deep red (±crystals), C–, KC–].
Ecology and distribution. Truong et al. (2011) described U. grandisora from the Galapagos and at the time presumed it to be endemic; among historical collections Truong & Clerc (2016) since then discovered a single herbarium specimen from the continent (Venezuela); the species generally appears rare and overlooked. It is not common in the Galapagos either, where only nine specimens are currently known, collected in the transition and humid zone, on bark or wood, in open habitats (fenceposts and isolated trees in farmland areas, open woodlands).