Type: Ecuador, Galápagos Islands, Plaza Sur Island, 0˚ 34’ 59” S, 90˚ 9’ 54” W, alt. 1 m, coastal zone; eastern part with scattered and low vegetation of Sesuvium portulacastrum & Tiquilia galapagoa with occasional Opuntia, western part also with scattered scrubs of Grabowskia boerhaaviaefolia, Maytenus octogona, and Castela galapageia, on wood, twig, 21/02/2006, Aptroot, A. 64433 (CDS no. 31001–holotype; ABL–isotype).
Etymology. Named in honour of Charles Darwin, and to recognize the scientific accomplishments of the Charles Darwin Research Station.
Thallus shrubby, greenish grey, decaying parts becoming red, without a distinct holdfast, relatively densely branched, up to 15 cm in diam., but usually much smaller (3–7 cm); branches initially upright, hanging down when older, in most parts distinctly canaliculate and in section broadly crescent-shaped to ± flattened, sometimes also markedly curved in the longitudinal direction and frequently with curved lobe tips (“shepherds’ crooks”), slender to relatively broad (up to 15 mm wide), occasionally anastomosing, leaving oval to elongated holes; lobe margins with rounded, irregular warts from which irregular, punctiform or sublinear pseudocyphellae develop; soralia absent; apothecia common, ca. 2–7 mm in diam., cupular, laminal to subterminal, disk yellowish to pinkish grey, branches often bent at the apothecia (geniculate), verrucose below with crateriform pseudocyphellae, ascospores hyaline, 1-septate, narrowly oblong, usually ± curved, 10–12 × 4–5 μm; pycnidia mostly marginal, hemispherical, 0.1–0.2 mm in diam., ostiole pale ochre; conidia rod-shaped, 5–6 × 0.5–1.0 μm; medulla K+ orange yellow, soon red, UV+ white or UV- (salazinic ± sekikaic ± divaricatic acid); cortex with usnic acid, occasionally (e.g. in the type collection) also with atranorin.
This species is corticolous or lignicolous, rarely also saxicolous and grows throughout the coastal and arid zone, rarely higher. It is often abundant on twigs and branches of coastal shrub and dry forest. The species is similar to R. complanata, which, however, has an irregularly flattened, not distinctly canaliculate surface and laminal tuberculate pseudocyphellae. Ramalina sideriza is also vaguely similar in habitus and like R. darwiniana has hooked lobe tips, but it has flattened lobes with a distinctly striate, often coarsely linear pseudocyphellate surface.
Selected specimens examined. Ecuador: Galápagos: Isabela Island, Cerro Alcedo, highest cinder cone along the trail going up the E-slope, 0˚ 23’ 37” S, 91˚ 1’ 31” W, alt. 250 m, arid lowlands, basalt outcrops, at the bottom, scattered Bursera graveolens trees and shrubs of Castela galapageia, on bark of Bursera, 10 iii 2006, A. Aptroot 65030 (CDS no. 31612); Pinta Island, at the S-coast, a little E of Cabo Chalmers, 0˚ 33’ 2” N, 90˚ 46’ 3” W, alt. 10 m, coastal zone; old lava flow with scarce vegetation (Opuntia galapageia, Alternathera filifolia, Prosopis juliflora), on bark, dead twigs of Bursera graveolens lying on the ground; semi-shaded, wind- and rain-exposed, 01 iii 2007, F. Bungartz 6077, (CDS no. 33756); Pinzón Island, along the trail going up from Playa Escondida, 0˚ 35’ 58” S, 90˚ 39’ 32” W, alt. m, arid zone with Prosopis juliflora, Alternanthera filifolia, Maytenus octogona, and Croton scouleri, on bark, twigs, 16 ii 2006, A. Aptroot 64160, (CDS no. 30724); Plaza Sur Island, eastern part, 0˚34’ 59’ S, 90˚9’ 54” W, alt. 1 m, coastal zone, scattered and low vegetation of Sesuvium portulacastrum and Tiquilia galapagoa with occasional Opuntia spp. in between, on wood of dead twigs, 21 ii 2006, A. Aptroot 64433 (CDS no. 31001); Rábida Island, NW-side of Rábida, 0˚ 23’ 59” S, 90˚ 42’ 35” W, alt. 27 m, on top of coastal cinder cliff above the beach; N-exposed slope with lava boulders, rocks and young Bursera graveolens trees (max. 3 m in height), on bark, twigs of Bursera graveolens; sunny, wind- and rain-exposed, 21 vii 2006, F. Bungartz 5351, (CDS no. 29567); San Cristóbal Island, near Rosa Blanca, inland from the SE-coast of the island, 0˚ 49’ 13” S, 89˚ 21’ 38” W, alt. 16 m, arid zone; open Bursera graveolens woodland with Scutia spicata in the understory on top of lava flow, on bark, twigs of Bursera graveolens; sunny, wind- and rain-exposed, 23 iv 2007, F. Bungartz 6412, (CDS no. 34627); Santa Cruz Island, Puerto Ayora, near CDRS, 0˚ 44’ 32” S, 90˚ 18’ 10” W, alt. 1 m, on rock (basalt lava), 24 v 2005, A. Aptroot 63074, (CDS no. 29802); Charles Darwin Research Station, path near shoreline west of library, growing on Maytenus octagona, 30 x 1982, P. Bentley 17, (CDS no. 10881); E of Puerto Ayora, near Charles Darwin Research Station, on lava blocks of wall around tortoise pens, 1 m alt., 18 February 2006, A. Aptroot 64172 (CDS 30735); near Los Gemelos craters, 0˚ 36’ 31” S, 90˚ 22’ 4” W, alt. 350 m, on wood, 31 v 2005, A. Aptroot 63397 C, (CDS no. 30150); along the trail from Puerto Ayora to Bahía Tortuga, above the dunes, 0˚ 45’ 36” S, 90˚ 19’ 55” W, alt. 16 m, coastal zone with Cryptocarpus pyriformis & Prosopis juliflora, on bark, dead twigs of Prosopis juliflora lying on open ground, sunny, wind- and rain-exposed, 05 i 2006, F. Bungartz 3396, (CDS no. 27063); Santiago Island, ca. 7 km inland from the E-coast, ± at the same latitude as Bahía Sullivan, 0˚ 17’ 4” S, 90˚ 38’ 21” W, alt. 190 m, arid zone; shrubland of Castela galapageia and Macraea laricifolia with occasional trees of Bursera graveolens, Zanthoxylum fagara and Psidium galapageium on NE-exposed slope, on bark, trunk of Acacia rorudiana (ca. 20 cm in diam.), W-exposed; shaded, wind- and rain-sheltered, 17 vii 2006, F. Bungartz 5124, (CDS no. 29337).
from: Aptroot, A. & Bungartz, F. (2007) The lichen genus Ramalina on the Galapagos. The Lichenologist39(6): 519-542.