Galapagos Species Database

Material at CDS matches the 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. Comparison with further material of R. sideriza is necessary to confirm the identity of the Galapagos specimens; meanwhile they are included in this species. 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 can, however, be 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. Furthermore, the lobe tips of R. sideriza are curled backwards into ‘‘shepherds’ crooks’’, whereas lobes of R. complanata are tapered and blade-like.