Gerlach, A.C.L./ Eliasaro, S./ Clerc, P./ Silveira, R.M.B. 2014: [Abstract:] Pendulous Usnea species in Southern Brazil. - In: : Livro de Resumos do Sétimo Encontro do Grupo Brasileiro de Liquenólogos. 1. Grupo Brasileiro de Liquenólogos pp. 64. [RLL List # 248 / Rec.# 39031] Abstract: The genus Usnea typically presents a shrubby to pendant thallus. Pendulous thallus exhibits branches running parallel almost from the base to the apices, while in subpendulous thallus the primary branches are ± diverging and erect whereas the secondary branches run more parallel, hanging down. Although the growth form usually has little taxonomic value because it is much influenced by environmental parameters this character is here used to delimit a group of large species characterized by a pendant thallus. As part of a taxonomic revision of the genus Usnea, pendulous specimens were collected in the states of Paraná, Santa Catarina and Rio Grande do Sul. Specimens from the following national herbaria were included: ICN, UPCB, HAS, MBM and RB. Type species from the herbaria UPS, H, BM, W were also analyzed. The specimens were studied using standard methods used in the systematics of Usnea. Morphological characters were analyzed and the secondary metabolites were identified by thin layer chromatography. Furthermore anatomical features such as the percentages of cortex, medulla and axis thickness were measured. 22 species were found: Usnea alata Motyka, U. angulata Ach., U. arthroclada Fée, U. articulata (L.) Hoffm., Usnea aff. cavernosa Tuck., U. columbiana Motyka, U. dasaea Stirt., Usnea cf. dimorpha (Müll. Arg.) Motyka, U. dodgei Motyka, U. geissleriana P. Clerc, U. malmei Motyka, U. merrillii Motyka, U. mexicana Vain., U. papillata Motyka, U. perhispidella J. Steiner, Usnea aff. poliothrix Kremp., U. regia Motyka, U. sanctaeritae P. Clerc & Herrera-Campos, U. subelegans (Vain.) B. de Lesd., U. subflammeaP. Clerc, U. subgracilisVain. and U. subscabrosa Motyka. Usnea angulata and U. malmei were the most abundant and frequent species in the study area. They usually reach more than two meters long in places of higher altitudes (900─1500m). The identification of Usnea cf. dimorpha remains uncertain until thallus with mature soralia are collected. Usnea aff. cavernosa and Usnea aff. poliothrix may in fact correspond to still undescribed species. Usnea columbiana is cited for the first time to Brazil and Usnea dodgei, U. mexicana, U. papillata, U. sanctaeritae, U. subflammea and U. subscabrosa to Southern Brazil. Others species with pigmented cortex or medulla may have (sub)pendulous thallus; they will be studied elswhere. Images of the overall thallus aspect are presented and the morpho-anatomical and chemical diagnostic features are discussed.
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