Inferring the extinction of species known only from a single specimen

Many species are poorly known, with the sum of our knowledge represented by specimens in museums. For assessment of conservation status the most enigmatic and challenging species are probably those known only from a single specimen. We examine the potential persistence of such species using the orchid flora of Madagascar as a case study. We apply a statistical method that tests the likelihood of species presence in relation to the time when a species was collected and a measure of annual collection effort, calculated in three ways based on specimen collection over time. The results suggest that as of 2000 up to nine of the 236 orchid species known from a single specimen may be inferred to be extinct under at least one of the three methods of estimating collection effort and extinction. In addition, up to two additional species are likely to be extinct by 2018 assuming no new collections were made by that time. Substantial collection effort and/or additional evidence will be needed to reach a decision on the persistence of more recently observed species known only from a single collection. This represents a challenge for conservation practitioners.

A botanical mystery solved by phylogenetic analysis of botanical garden collections: the rediscovery of the presumed-extinct Dracaena umbraculifera

Extinction is the complete loss of a species, but the accuracy of that status depends on the overall information about the species. Dracaena umbraculifera was described in 1797 from a cultivated plant attributed to Mauritius, but repeated surveys failed to relocate it and it was categorized as Extinct on the IUCN Red List. However, several individuals labelled as D. umbraculifera grow in botanical gardens, suggesting that the species’ IUCN status may be inaccurate. The goal of this study was to understand (1) where D. umbraculifera originated, (2) which species are its close relatives, (3) whether it is extinct, and (4) the identity of the botanical garden accessions and whether they have conservation value. We sequenced a cpDNA region of Dracaena from Mauritius, botanical garden accessions labelled as D. umbraculifera, and individuals confirmed to be D. umbraculifera based on morphology, one of which is a living plant in a private garden. We included GenBank accessions of Dracaena from Madagascar and other locations and reconstructed the phylogeny using Bayesian and parsimony approaches. Phylogenies indicated that D. umbraculifera is more closely related to Dracaena reflexa from Madagascar than to Mauritian Dracaena. As anecdotal information indicated that the living D. umbraculifera originated from Madagascar, we conducted field expeditions there and located five wild populations; the species’ IUCN status should therefore be Critically Endangered because < 50 wild individuals remain. Although the identity of many botanical garden samples remains unresolved, this study highlights the importance of living collections for facilitating new discoveries and the importance of documenting and conserving the flora of Madagascar.

Aloe belitsakensis (Asphodelaceae): a new species from north-western Madagascar

Madagascar is a major centre of diversity for the leaf-succulent genus Aloe Linnaeus (1753: 319) accounting for roughly a third of Aloe species (Carter et al. 2011). Approximately 128 species and 161 taxa are known from the region and all are restricted to Madagascar (Rakotoarisoa et al. 2014) and/or the nearby Mascarene archipelago. New taxa are described from these islands at a rate that rivals the ongoing discovery of aloes elsewhere in their natural range, on the African continent or Arabian Peninsula (Crouch et al. 2013). Extinction risks are alarmingly high among species of Aloe in this region. Conservatively, 39% of species are known to be threatened, and this figure is likely to be significantly higher (Rakotoarisoa et al. 2014), since several species have not been observed or collected for many decades. The Kew Madagascar Conservation Centre (KMCC) aims to record and collect the rare and threatened flora of Madagascar to ensure its conservation, and the genus Aloe is a priority for the dryland programme.

The reinstatement and rediagnosis of the madagascan genus Rhodocodon (Asparagaceae, Scilloideae), with validation and remarks on H. Perrier’s taxa

The genus Rhodocodon is here reinstated based on morphological, biogeographical and molecular evidence. On the basis of the work presented by H. Perrier de la Bâthie in Flora of Madagascar, one subgenus and ten species of Rhodocodon are validated here. Furthermore, Rhodocodon madagascariensis and R. urgineoides are lectotypified, and Hyacinthus cryptopodus and Urginea mascarenensis are transferred to Rhodocodon. A complete morphological description for all 13 accepted species of Rhodocodon is provided, including data on biology, ecology and distribution. Furthermore, an identification key for the Rhodocodon species is presented.