Novitates Gabonenses 86. The Begonia clypeifolia complex (Begoniaceae) unravelled

Abstract

Background - The acquisition of more data on the highly variable species Begonia clypeifolia Hook.f., necessitated a review of the taxonomic situation. Methods - A detailed morphological study was performed on herbarium material. Standard practices of herbarium taxonomy have been applied. Preliminary assessments of the IUCN Red List categories of threat were performed using the IUCN criteria and guidelines. Key results - The material revealed the existence of two new species and two new subspecies. All are endemic to the notoriously species-rich region between southern Cameroon and southwestern Republic of the Congo. The new taxa are: B. monte-alenensis Sosef (IUCN status Vulnerable under criterion D2), B. puberula Sosef (IUCN status Critically Endangered under criterion B2), B. clypeifolia subsp. mayombensis Sosef (IUCN status Endangered under criterion B1 and B2) and B. clypeifolia subsp. celer Sosef (IUCN status Vulnerable under criterion B1 and B2). The morphological distinctions between these taxa and B. clypeifolia subsp. clypeifolia (IUCN status Least Concern) are discussed, their distribution and habitat types are provided as well as a citation of all specimens studied. Conclusions - The five new hypotheses about taxonomic distinctions within the B. clypeifolia complex, now based upon a thorough morphological study, should preferably be tested using molecular methods.