Galapagos Species Database

Chemistry. Medulla 1) K+ yellow slowly turning orange, P+ deep orange: stictic gr., 6 traces of norstictic acids, rarely 6 traces of unidentified triterpenoids UT6 (Andes); 2) K+ yellow turning red, P+ orange-yellow: salazinic, 6 norstictic acids (currently the only chemotype known from Galapagos); 3) K+ yellow turning red-orange, P+ deep yellow: norstictic acid (Andes); 4) K and P2: unidentified tri-terpenoids UT2 (Andes).

Usnea erinacea is a fertile species characterized by a red-orange pigmentation in the cortex. The branches are tapering and terete, not inflated or constricted at the attachement point, with sub-terminal to terminal apothecia. When apothecia are lacking, the apices usually bear numerous pycnidia, looking like spherical protuberances. The cortex is thick and shiny (9–14%), the medulla compact (11.5–21%) and the axis medium to large (36–53.5%), with an A/M ratio . 1.5 (n 5 34). Chemotype 2 (salazinic and norstictic acids) is the only chemotype in the Galapagos and is rare in the Andes, whereas chemotypes 1 (stictic acid), 2 (norstictic acid) and 3 (tri-terpenoids UT2) occur exclusively in the Andes. Usnea sp. 2 is another fertile species with a red pigmentation in the cortex. It differs in the inflated branches that are constricted at the attachment point, a cornuta-type CMA with a laxer medulla and an A/M ratio , 1.5, and a different chemistry (tri-terpenoids UT6 alone). Young thalli of U. erinacea rarely have an A/M ratio , 1.5, but the branches remain cylindrical and not constricted at the attachment point. Usnea erinacea is possibly the fertile counterpart of U. rubicunda, sharing the same morphology apart from the presence/absence of soralia, the same chemotypes and a similar ecology. Specimens are rarely observed with both apothecia and soralia. In the neotropics U. erinacea is nevertheless rarer than U. rubicunda