Reassessment of Varronia bellonis - a threatened, endemic plant from Puerto Rico

Abstract

Varronia bellonis is a lianescent or recumbent shrub that is endemic to Puerto Rico where it is restricted to specific geology types with a limited extent on the western half of the island. The species occurs on serpentinite geology covered by serpentine derived soils in the west-central mountains and on limestone geology in the the northern karst region. The species area of occupancy is estimated to range between 108 km2 and 268 km2, and its extent of occurrence to be between 644 km2 and 852 km2. The number of locations are estimated to be four. There are 418 known mature individuals in the wild (Hamilton 2020a). The species was previously assessed as Critically Endangered (Linsky and Sustache 2014) based on available information. However, an international team have been collaborating to conserve the species and based on new information derived from this work, the species is reassessed as Endangered (EN), based on Criteria B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v), according to the IUCN Red List Categories and Criteria (version 3.1) and guidelines (Subcommittee IUCN Standards and Petitions 2016).Areas of suitable habitat across the native range of the threatened plant, V. bellonis, were surveyed by a team of experts between 2016 and 2019 to determine the species habitat preferences, identify threats to the species survival and provide an up-to-date meta-population status. The new information enabled members of the international team to reassess the species status, and will enable sound and scientifically based recovery actions to be recommended that can secure Varronia bellonis populations for the future. Parallel efforts are ongoing to explore the species population genetics and reproductive biology.