Ramalina usnea (Linnaeous) R. H. Howe, 1914

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 : 65-66

50. Ramalina usnea (Linnaeous) R. H. Howe

The Bryologist 17: 81 (1914) . Type :― MARTINIQUE (lectotype selected in Imshaug 1972: 317, LINN 1273–27 ).

Lichen usnea Linnaeous, Mantissa 1: 131 (1767).

Thallus corticolous, pendulous, contorted, up to 1 m long, greenish or pale yellow. Branches solid, flattened, terete or subterete, often contorted, without soredia, surface smooth or weakly striate, up to 3.5 mm thick. Pseudocyphellae linear, marginal, laminal, flat or weakly convex. Chondroid tissue distinctly cracked, continuous. Medulla white, loose. Pycnidia not seen. Apothecia lateral; epithecium 4–6 µm thick; hypothecium 76–90 µm thick; hymenium 50–65 µm thick. Ascospores 1–septate, long-fusiform, 18–22 x 3–4 µm.

Chemistry (TLC, HPTLC): This species presents 8 strains which are summarized in the Table 10. Strain 1. Divaricatic and protocetraric acids (Bunting 5274; Steyermark et al. 123339; Berry et al. 3778; Liesner & González 12160–A; Vareschi 317, 7757; Nee & Mori 4028; Pannier 833; Pittier 10506; Mägdefrau 675; Zuluaga 1644–D; Morales 100–A; González 2128; Dennis 2213; Vareschi 5254; Tamayo 780). Strain 2. Homosekikaic, sekikaic (tr.), succinprotocetraric and protocetraric acids (Vareschi 6879). Strain 3. Sekikaic, 4ˊ– O –demethysekikaic (tr.), boninic (tr.) and protocetraric acids (Vareschi 5258–A). Strain 4. Norstictic, stictic, connorstictic and hypoprotocetraric acids (Aristeguieta 2265). Strain 5. Homosekikaic and sekikaic acids (Aristeguieta & Vareschi 5792). Strain 6. Divaricatic acid (Marcano 163–92). Strain 7. Sekikaic, boninic, protocetraric and fumarprotocetraric acids (Cleef 6043). Strain 8. Homosekikaic, sekikaic, succinprotocetraric and protocetraric acids (Vareschi 3446).

Ecology and distribution: In Venezuela this species is found growing on Tabebuia sp. , and other shrubs in deciduous forests on limestone; in Colombia, it grows on Quercus humboldtii in forests at 80–3500 m (Fig. 30). It is known from North America (Florida and Texas), the Caribbean ( Jamaica, Martinique, Santo Domingo, Puerto Rico), México and South America ( Argentina, Chile, Brazil, the Galápagos Islands, Paraguay, Uruguay, Colombia and Venezuela).

Remarks:. Ramalina usnea could be confused with R. chilensis and R. bogotensis but R. chilensis differs in having short-fusiform spores (12–14(–16) x 2–2.5 µm) whereas R. bogotensis has granular soredia. Ramalina usnea is also very similar to R. tenaensis but this latter is distinguished by the shape and size of its spores and its verruculose surface. Ramalina usnea shows eight chemical strains, with sekikaic acid and its aggregates and divaricatic acid as major medullary substance with substances in the protocetraric acid complex as accessory substances (Table 10). Strain 4 contains only β-orcinol depsidones. Rundel (1978) reported three strains (chemotype) from tropical and subtropical North and South America: strain 1, producing sekikaic and ± homosekikaic acids; strain 2, producing divaricatic acid; and strain 3 yielding usnic acid only (no medullary substances). Kashiwadani & Kalb (1993) and Gumboski (2016) reported divaricatic acid and sekikaic acid and its aggregates as the major substances in specimens of this species from Brazil. Marcano & Sipman (2020) reported the presence of sekikaic acid and its aggregates, and of the protocetraric acid complex as accessory substances in specimens of this species from the Venezuelan Amazonas.

Specimens examined: COLOMBIA: Cundinamarca: San Cayetano, hacienda Portugal , Quercus forests, 2750 m, 8 November 1972, A . Cleef 6043 ( B). Chocó: Los Katíos National Park, Alto del Limón , 250 m, 10 May 1983, S . Zuloaga 1644–d ( B, herb. INDERENA) . VENEZUELA: Amazonas: La Esmeralda, near Rio Orinoco , corticolous, submontane forests, 150 m, February-1994, L . Galiz & V . Marcano AMA– s/n ( TFAZ, VEN) . Aragua: Rancho Grande National Park , 7 July 1956, V . Vareschi 5254, 5258a ( VEN) . Bolívar: Near Río Caroní , August 1957, F . Pannier 833 ( VEN); Cerro Bolívar, near Ciudad Piar , 700 m, April 1954, L . Aristeguieta 2265 ( VEN). Dto. Federal: Los Caracas, 200 m, 24 April 1971, M . Nee & S . Mori 4028 ( VEN); between Chichiriviche and Oricao, 400 m, 6 July 1958, Dennis 2213 ( VEN); Los Caracas, 80 m, 10 July 1962, V . Vareschi 7757 ( VEN) . Falcón: Cerro Cocorote , 16 September 1989, A . Gonzales 2128 ( VEN); near Tucacas, 4 July 1954, V . Vareschi 3446 ( VEN); Cerro Santa Ana, Peninsula de Paraguana , January 1939, F . Tamayo 780 ( VEN); Near Coro, 200 m, 3 April 1958, Vareschi 6879 ( VEN); near Coro , Medanos de Coro , 10 m, July 2003, V . Marcano 3439 (herb. lich. V. Marcano) . Miranda: Laguna Grande , 0–30 m, 27–28 May 1981, P . Berry , A . Hernandez & D. Fernandez 3778 ( VEN); Los Canales de Higuerote , 100 m, 116 December 1956, L . Aristeguieta & V . Vareschi 5792 ( VEN) . Sucre: Peninsula de Araya, ca 4 km west of Caimancito , 10 m, 20 May 1981, R . Liesner & A . Gonzales 12160– A ( MO, VEN) . Mérida: Santo Domingo, Paramo de Mucubají , 3500 m, March 1992, V . Marcano 163–92 ( MER); El Paramito, Hacienda Luis Davila, Chiguara, 1300 m, 2 April 1984, A . Morales 100–a ( MERF, B); Paramo La Vicyoria , Sierra Nevada de Merida, 3200 m, 25 January , 2021, V . Marcano & L . Castillo 21–187 ( MER, herb. lich. V. Marcano) . Zulia: between Maracaibo and Machiques , 14 October 1922, H . Pittier 10506 ( VEN); near to Maracaibo , on Tabebuia sp. , 100 m, 21 July 1977, G . S . Bunting 5274 ( NY, VEN); Sierra de la Corbata, 3–4 km NNE parcelamiento Cachirí, 100–360 m, 5 June 1980, J . Steyermark , G . Davidse & A . Stoddart 123339 ( MO, VEN); near Maracaibo , 18 March 1951, V . Vareschi 317 ( VEN); Maracaibo , Hacienda Trinidad, 4 April 1958, K . Mägdefrau 675 ( VEN) .