Usnea fragilescens Lynge

van den Boom, Pieter P. G., Clerc, Philippe & Ertz, Damien, 2015, New records of lichens and lichenicolous fungi from La Gomera (Canary Islands, Spain), including the new species: Usnea boomiana P. Clerc, Candollea 70 (2), pp. 165-177 : 172

Usnea fragilescens Lynge

Notes. – This taxon was mentioned for the first time for the Canary Islands by TAVARES (1952) under the name U. mollis Stirt. , a synonym of U. fragilescens ( CLERC, 1987) . This indication was then taken up again by CHAMPION & SANCHEZ PINTO (1978), HAFELLNER (1995) and HERNÁNDEZ PADRÓN & PÉREZ-VARGAS (2010), “collected on Tenerife”. Usnea cornuta Körb. (= U. inflata (Duby) Motyka ) a frequent and variable species was not mentioned for the Canary Islands in the report of TAVARES (1952). There is thus a high probability that the species reported as U. mollis by TAVARES (1952) was in fact U. cornuta . So the report in this paper of U. fragilescens on La Gomera is the first credible mention of this species for the Canary Islands. One of the specimen (Hernàndez & Pérez 56615) out of the two collected by Hernàndez & Perez on La Gomera corresponds well to the description of U. fragilescens given by CLERC (1987) with the stictic acid group as medullary substances. The second specimen (Hernàndez & Pérez 56616) however differs in the presence of thamnolic acid as medullary substance. This constitutes a new chemotype for Usnea fragilescens .

Material examined. – 12, Er, Boom 46120; 59, Hernàndez & Pérez 56615; 60, Hernàndez & Pérez 56616.