Galapagos Species Database

Thallus erect-shrubby, rarely sub-pendulous, to 7 (12) cm long, sometimes with a reddish colour, especially in the basal part; ramifications anistomic-dichotomous; trunk concolorous with the branches; branches tapering to strongly irregular; segments terete, slightly to distinctly inflated; lateral branches slightly to distinctly constricted at the attachment point; foveoles and maculae absent; papillae few to numerous on the main branches, hemispherical, sometimes eroding at the top; fibrils short (to 2 mm), thin, often numerous and densely covering parts of the branches; soralia minute, of irregular shape, rarely enlarging or fusing in irregular patches, even to 6 stipitate, developing mainly on terminal branches on the cortex ad initio; isidiomorphs usually abundant, to 1 mm long, often developing into isidiofibrils that are mixed with fibrils on the branches; cortex 5–7.5%, thin and fragile, shiny in section; medulla 26.5–34%, 6 loose to dense, with an orange pigmentation just below the cortex, sometimes faint and discontinuous; axis 21–34%, moderately thin, (n = 26); apothecia very rare, to 4 mm in diameter, with numerous cilia; spores hyaline, obovoid, 11–12.5 3 6–7.5 mm (n = 1); pycnidia not seen. Chemistry: 1) Medulla K+ yellow turning red, P+ yellow to orange: salazinic, galbinic, norstictic acids (n = 22); 2) K and P2: unidentified triterpenoids UT6 (n = 2).

Usnea subdasaea is characterized by the irregular branches that are 6 inflated and constricted at the attachment point, the numerous fibrils and isidiofibrils densely covering distinct areas on the branches and the orange subcortical pigmentation in the medulla. Differentiation. For differences with Usnea crocata, U. grandisora, U. steineri and U. subcornuta see the description of these species. Usnea dasaea (Clerc 2008; Herrera-Campos et al. 2001) has a similar morphology and chemistry, but differs by the absence of pigmentation in the medulla and the absence of isidiofibrils. Fibrils in U. dasaea also tend to be thicker and more spinulous. Usnea dasaea is more common than U. subdasaea in the Neotropical Andes, but much rarer in the Galapagos.