Social media have become useful tools for providing new biodiversity data, with, for example, species discovered on Flickr (Semachrysa jade, Neuroptera, Chrysopidae; Winterton et al., 2015, Zookeys, 214, 1–11), Facebook (Hoya amicabilis, Apocynaceae, Asclepiadoideae; Rahayu & Rodda, 2019, Nordic Journal of Botany, 37, e02563), Twitter (Ameronothrus retweet, Acari, Oribatida; Pfingstl et al., 2021, International Journal of Acarology, 48, 348–358), Instagram (Oligodon churahensis, Reptilia, Serpentes; Mirza et al. 2021, Evolutionary Systematics, 5, 335–345) and Youtube (Leichhardtia weari, Apocynaceae, Asclepiadoideae; Gateble et al. 2023, Pyhtotaxa, 591, 91–100).
Here we report a new record discovered on Facebook and Instagram of Dipterocarpus littoralis (Dipterocarpaceae), a tree endemic to the 6.6 km2 West Nusakambangan Nature Reserve in the westernmost part of Nusakambangan Island in Central Java Province, Indonesia. This tree is categorized as Critically Endangered on the IUCN Red List because of its restricted distribution, small population size, and continuing population decline caused by habitat conversion and invasive species.
Posts on Facebook (bit.ly/3MfEnc3) and Instagram (bit.ly/3LlAa67) on 29 April 2023 showed photographs of a group of fruits and leaves of a tree species of the Family Dipterocarpaceae. The images were tagged as Dipterocarpus sp., and were from Tasikmalaya, a regency in West Java Province c. 70 km from West Nusakambangan Nature Reserve, in a hilly forest at 100 m altitude. Based on the obturbinate shape of the fruit calyx tube and the high number of secondary nerves (> 19 pairs), the images can be firmly assigned to Dipterocarpus littoralis. The species is reported to be a lowland segregate of the widespread submontane Dipterocarpus retusus, which differs from the former by subglobose fruit calyx and 16–19 pairs of secondary nerves.
A survey in the new locality is required to assess the population size and any threats. As this finding will significantly increase the extent of occurrence, area of occupancy and number of locations of the species, its conservation status under criterion B of the IUCN Red List will need to be reassessed. In addition, living collections of the species from the new locality need to be added to the current ex situ collections at the Bogor Botanic Gardens, to represent the genetic diversity of the species fully.