A new and endemic species of Drosera (Droseraceae) from Madagascar

Background and aims – This study is part of an ongoing revision of the world Drosera species. During herbarium revisions of Drosera from Madagascar, a new species was identified and is here described.Methods – The species’ morphology is described based on herbarium studies and observation of living plants in situ, and ecological notes from field observations are provided. The species is compared and contextualized within the current subgeneric classification of Drosera.Key results – The new species, Drosera arachnoides, is recognized as most closely related to another Malagasy-endemic, D. humbertii, from which it is morphologically and ecologically distinct. The new species is placed within D. subg. Drosera sect. Ptycnostigma. Based on the restricted occurrence, the species is assessed as Vulnerable, following IUCN categories and criteria. A key to the Drosera species from Madagascar is provided.Conclusion – Drosera arachnoides is the second endemic Drosera species in Madagascar and raises the total number of species on the island to six.