Ceratostema is a genus in the Ericaceae comprising, approximately 50 species and is distributed from Venezuela and Guyana to northern Peru in South America. The country with the greatest diversity of the genus is Ecuador, where most taxa are restricted to the submontane and montane forests of the eastern slopes of the Andes. The " auriculatum group" refers to a set of species restricted to south-eastern Ecuador, characterised by plants with an epiphytic and pendant habit, amplexicaul leaves that partially enclose the flowers, few-flowered inflorescences provided with small floral bracts and bracteoles and a calyx with a non-prominent limb. Two new species of Ceratostema from the Morona Santiago province, Ecuador, belonging to the informal morphological “ auriculatum ” group are described and illustrated here. Ceratostema gearyana has plinerved, suborbicular leaves that are pruinose with lobes that do not overlap at the base; the mid-vein that is raised throughout its length; and a calyx with an obconic hypanthium with deltate-ovate lobes. It is compared with C. cutucuense from which it is distinguished by the smaller leaves, the glabrous floral parts, the hypanthium smaller, obconic, obscurely pentagonal, the larger calyx lobes and the corolla with narrowly linear-triangular lobes. Ceratostema moronasantiagoensis has pinnately veined, ovate leaves, with basally imbricate lobes, deltate calyx lobes and a fuchsia-red, pubescent corolla with puberulous stamens. It is most similar to C. auriculatum , but it is distinguished by the calyx limb unlobed at the base, the smaller, acuminate calyx lobes, not conspicuously nerved, pubescent overall, the fuchsia red, pubescent corolla, with longer lobes, and the puberulent, longer filaments. The taxonomic affinities of the two new species are discussed, and information about their distribution, habitat and conservation status is provided.
Jiménez et al. (Mon,) studied this question.