Ramalina tenuissima V. Marcano & A. Morales, 1994

Marcano, Vicente, Méndez, Antonio Morales & Prü, Ernesto Palacios, 2021, The genus Ramalina Acharius (Ascomycota, Lecanoromycetes, Ramalinaceae) in northern South America, Phytotaxa 504 (1), pp. 1-77 : 63-64

4. Ramalina tenuissima V. Marcano & A. Morales

The Bryologist 97: 31 (1994) . Type:― VENEZUELA. Mérida: La Carbonera, between Mérida city and La Azulita , 2200 m, 1 March 1975, Lopez-Figueiras & Keogh 9236 (holotype MERF!).

Thallus corticolous, pendulous, soft, pale yellow, up to 32 cm long, dichotomously to iregularly branched. Branches filiform, filamentous, subterete, angular or flattened, 0.3–0.7 mm broad. Branchlets numerous, divergent terminating in soralia. Pseudocyphellae linear, longitudinally arranged (Fig. 9). Peripheral chondroid tissue forming discontinuous layers. Medulla dense. Pycnidia and apothecia not seen.

Chemistry (TLC, HPTLC): Strain 1. Sekikaic acid (V. Marcano 5263, 5264, 5266, 5267, 5268; Lopez-Figueiras 26179). Strain 2. Nil (Vareschi 6131–II). Strain 3. Ramalinolic and boninic acids (Aguirre & Sipman 5235–A). Strain 4. Psoromic and salazinic acids (Aguirre & Sipman 5414). Strain 5. Sekikaic and boninic (tr.) acids (Aguirre & Sipman 5726–B). Strain 6. Psoromic acid (Cleef 4210–C).

Ecology and distribution: Ramalina tenuissima is found growing on trees and shrubs in very moist rainforests at subalpine altitudes (2200–3400 m). In Colombia, it occurs on dead treetrunks in pastures, as well as an epiphyte on Aragoa . It is known only from northern South America ( Colombia and Venezuela).

Remarks: Ramalina tenuissima resembles R. usnea , and both species can contain sekikaic acid as a chemical constituent. However, R. tenuissima has a non-contorted, filiform, filamentous thallus, with sorediate and pseudocyphellate branches, whereas in R. usnea the branches are broader, contorted and lack both soralia and pseudocyphellae. Ramalina tenuissima shows six distinct chemical strains with sekikaic acid and its aggregates (strains 1, 3 and 5) or psoromic acid (strains 4 and 6) as major medullary substances. Strain (2) lacks medullary substances.

Additional specimens examined. COLOMBIA: Huila: Municipio La Plata, E-side of Cordillera Central, vereda La Candelaria , finca Merenberg , Volcan Merenberg , 2400 m, 30 September 1984, J . Aguirre & H . Sipman 5842–g ( B) . Risaralda: W-slope of Cordillera Central, municipio Santa Rosa de Cabal, ca. 500 m S of Finca La Sierra , 3750 m, 16 September 1984, J . Aguirre & H. J. M . Sipman 5726– B ( B, COL) . Cundinamarca: Between Cogua and San Cayetano, Laguna Verde , 3630 m, A . Cleef 4210– C ( B); Municipio Supatá, Alto El Tablazo, along track from radar station to Supatá, 3400 m, 11–12 September 1984, J . Aguirre H. J . Sipman 5235 ( B) . VENEZUELA. Mérida: Laguna Coromoto , 3400 m, 13 January 1957, V . Vareschi 6131–II ( VEN) . Táchira: Paramo de Tamá, Hale & Lopez-Figueiras 4537l ( MERF, US) , V . Marcano 5263, 5264, 5266, 5267, 5268 ( MERF). Betania, near Paramo de Tamá, Lopez-Figueiras 26179 ( MERF) .