Diversity of the Vascular Plants of the Gulf of Guinea Oceanic Islands

Abstract

Despite a long history of botanical collecting in the three oceanic islands of the Gulf of Guinea, no recent studies have documented floristic patterns. This chapter summarizes information on the vascular plants of the islands, including inventories conducted on Príncipe and São Tomé since 2017, as well as two recent expeditions to Annobón. An updated database of the vascular flora was compiled, which includes 14,376 records representing 1285 species and infraspecific taxa (1028 native). Príncipe has 445 species and infraspecific taxa (394 native), São Tomé has 1044 (842 native), and Annobón has 344 (274 native). Recent inventory work has generated collections of more than 90% of the endemic woody species. Several very rare taxa were rediscovered, including Balthasaria mannii (Oliv.) Verdc., 1969 (Pentaphylacaceae) and Psychotria exellii R. Alves, Figueiredo and A.P. Davis, 2005 (Rubiaceae), neither of which had been seen for more than 50 years. At least 17 species new to science were also discovered on Príncipe and São Tomé. Of the 1028 indigenous taxa, 164 (16%) are currently considered endemic to the islands. Of the 285 species evaluated according to the IUCN Red List criteria, 2 (0.7%) were Data Deficient, 226 (79.3%) Least Concern or Near Threatened, 55 (19.3%) threatened (including 3 Critically Endangered, 21 Endangered, and 31 Vulnerable), and 2 (0.7%) Extinct. On São Tomé and Príncipe, 325 plant species are used in traditional medicine, 37 of which are endemic. These results should be used to identify new priority sites for conservation, including on Annobón, where priority sites are less well defined.

Biodiversity in the Gulf of Guinea Oceanic Islands: A Synthesis

“…A preliminary list of 299 taxa (128 mosses, 171 liverworts and hornworts) is provided, and the authors note that several species likely remain undescribed or at least undocumented. Chapter 10 (Stévart et al 2022) presents an updated checklist of vascular plants, combining data from historical material and bibliographic references with extensive new field surveys conducted since 2017. The current number of vascular plants includes 1285 taxa, with 164 endemics, of which at least 18 are new to science.…”

Species Ecology in the Gulf of Guinea Oceanic Islands: Distribution, Habitat Preferences, Assemblages, and Interactions

“…Few studies have compiled geographically explicit information on species locations. Some exceptions include pteridophytes (Figueiredo 2002), endemic plants (Joffroy 2000;Stévart et al 2022), land snails (Holyoak et al 2020), and birds (Jones and Tye 2006). In some cases, information and even maps are shown, but details on how these were obtained are missing, as is the case for amphibians and reptiles (Pollo 2017) and threatened endemic birds (IUCN 2020a).…”

“…Even fewer species assemblages have been systematically surveyed across any of the islands. Some exceptions include plants (Fundação Príncipe 2019;Stévart et al 2022), terrestrial snails (Tavares 2020), benthic reefs and fishes (Maia et al 2018b), sea turtles (Ribeiro 2018;Hancock 2019), birds (Fundação Príncipe 2019Soares et al 2020), and bats (Rainho et al 2010). Bird surveys informed some of the first island-wide assessments of the distribution of community traits, such as species richness, composition, and structure (e.g.…”

“…Biological collections, in particular, play a fundamental role in enriching trait databases, and can even lead to unexpected discoveries. In the oceanic islands of the Gulf of Guinea, morphological analyses of more than 2500 plant specimens collected in 2019 and 2020 have yielded many new species, while rediscovering rare species and finding new records for the islands (Stévart et al 2022). Despite strong research effort in the 2000s (Figueiredo et al 2011), ongoing studies on orchids are still leading to the description of new species, especially for the genus Tridactyle.…”

“…Since then, the islands have captured the imagination and efforts of biologists, prompting scientific studies across multiple disciplines, many of which aim to clarify different aspects of ecology (e.g., Lima 2016), such as species distributions and habitat associations. Up to the 1990s, virtually all zoological publications focused on taxonomy (Gascoigne 1993), and this is still mostly the case for plants (Stévart et al 2022) and most invertebrates. Despite an increase in ecological research over the last few decades, key aspects of the ecology of species occurring in the Gulf of Guinea islands remain poorly documented, such as the influence community diversity and composition has on ecosystem processes.…”