New to Galapagos; the material collected during this study corresponds well to specimens collected by A. Stewart in Academy Bay during the Expedition of the Californian Academy of Sciences to the Galapagos Islands, 1905-1906. This CAS material was annotated by H. Kashiwadani in 1999 as R. sideriza, a species described by Zahlbruckner from Hawaii. However, the Galapagos material differs slightly from some exsiccati collections identified as R. sideriza from Hawaii (Hawaii, Volcanoes Ntl. Park, 4000 ft, Weber & Bujakiewicz, distributed in Weber, Lich. Exs. no 633), which has consistently marginal apothecia and is partly geniculate. It is included in this species here pending further studies. Comparison with further material of R. sideriza is necessary to confirm the identity of the Galapagos specimens.

The Galapagos specimens are similar to R. complanata and the CAS material that was annotated by Kashiwadani had previously been identified as this species. All Galapagos material is, however, reliably distinguished from R. complanata by its conspicuously striate lobe surface, which soon develops into distinct parallel ridges abrading into broadened, linear pseudocyphellae. Unlike R. complanata, the lower surface of apothecia in R. sideriza is relatively smooth and not tuberculate or ridged. Lobe tips of R. sideriza are curled backwards into “shepherds’ crooks”, whereas lobes of R. complanata are tapered, blade-like.

The species is corticolous or lignicolous, rarely saxicolous; a characteristic and common epiphyte throughout the coastal and arid zone.

Selected specimens examined. Ecuador: Galápagos: Tortuga Island (near Isabela Island), on bushes, 30 x 1905, A. Stewart 370 (CAS no. 640928); Española Island, v 1899, R.E. Snodgrass s.n. (CAS no. 691734); on dead branches, 25 ix 1905, A. Stewart 367 (CAS no. 640926); Genovesa Island, on bushes, 14 xi 1905, A. Stewart 369 (CAS no. 640927); Plaza Norte Island, 0˚ 34’ 47” S, 90˚ 9’ 47” W, alt. 1 m, coastal zone; vertical, inpenetrable thicket of Grabowskia boerhaaviaefolia and Scutia spicata with occasional Opuntia in between, on wood, twig, 21 ii 2006, A. Aptroot 64374 (CDS no. 30939); Santa Cruz Island, SE-side, on bushes, 27 x 1905, A. Stewart 371 (CAS no. 637096); Puerto Ayora, CDRS area, 0˚ 44’ 32” S, 90˚ 18’ 10” W, alt. 1 m, on rock (lava), 18 ii 2006, A. Aptroot 64171 (CDS no. 30734); Santa Cruz Island, 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 3395 (CDS no. 27062); San Cristóbal Island, hills S of Punta Pit at the NE-coast of the island, 0˚ 43’ 16” S, 89˚ 14’ 40” W, alt. 63 m, coastal zone; SSE-exposed ridge of basalt cliff, on rock at the SE-front of the cliff; semi-shaded, wind- and rain-exposed, 21 iv 2007, F. Bungartz 6174 (CDS no. 34386); Santiago Island, at the W-coast of the island in Bahía Ladilla, 0˚ 18’ 8” S, 90˚ 49’ 56” W, alt. 10 m, S-exposed coastal lava cliff and boulders, on rock at the S-exposed cliff face; sunny, wind- and rain-exposed, 22 vii 2006, F. Bungartz 5394 (CDS no. 29610).

from:
Aptroot, A. & Bungartz, F. (2007) The lichen genus Ramalina on the Galapagos. The Lichenologist 39(6): 519-542.