SYNOPSIS OF BEGONIA (BEGONIACEAE) FROM THE NORTHERN ARM OF SULAWESI AND SANGIHE ISLAND, INDONESIA, INCLUDING THREE NEW SPECIES Author Ardi, W. H. Research Center for Biosystematics and Evolution, National Research and Innovation Agency (BRIN), Jalan Raya Jakarta-Bogor Km 46, Cibinong, Kabupaten Bogor, Jawa Barat 16911, Indonesia. E-mail: wisn 005 @ brin. go. id. wisn005@brin.go.id Author Thomas, D. C. Research and Conservation, Singapore Botanic Gardens, National Parks Board, 1 Cluny Road, Singapore 259569. text Edinburgh Journal of Botany 2022 2022-08-18 79 405 1 50 http://dx.doi.org/10.24823/ejb.2022.405 journal article 10.24823/EJB.2022.405 1747-0036 10524193 9. Begonia insularum Irmsch. [§ Petermannia ], Bot. Jahrb. Syst. 50: 353 (1913) . – Type : Indonesia , Sulawesi , Sangir island , Warburg, O. 16107 ( holotype B [B100238023]) . Figure 7 . Distribution . Indonesia : endemic to Sulawesi , Sangihe (Sangir) Island (see Figure 2 ). Habitat . Transition of upland to hill rain forest with palms or secondary forest at 800 m elevation. Proposed IUCN conservation category . Vulnerable (VUD2). This species is known from only two collections, both of which have no exact locality information. Despite the legal protection of some areas on Sangihe (Sangir) Island due to being part of Sanger Gunung Api Uwu National Park, there are clear signs of anthropogenic disturbance, including habitation and nutmeg plantations, around the island. All available Begonia specimens from A, B, BM, BO, CEB, E, K, L and SING have been consulted, and therefore it must be assumed, at least until more intensive collecting on Sulawesi may reveal otherwise, that this species has a very restricted range. Therefore, this species is probably ‘prone to the effects of human activities or stochastic events within a very short time period in an uncertain future’ ( IUCN Standards and Petitions Subcommittee, 2019 ). Figure 7. Begonia insularum in its natural habitat, Sangihe Island. A, Habit; B, infructescence and male inflorescence. Photographs: Ullie Rachmawaty. Additional specimen examined . INDONESIA . Sulawesi . Sangihe Talaud Islands : Sangihe Island , 5 xi 1998 , D. Hicks & Anius 135 (K) . Begonia insularum is endemic to Sangihe (Sangir) Island . It is one of the most poorly known species in Sulawesi, being known from only a few specimen records and observations. Recently, the species was documented during a field survey by a colleague from Bogor Botanic Gardens (Ully Rachmawaty); however, no herbarium vouchers were made. Begonia insularum is similar to B. isoptera Dryand. ex Sm. from western Malesia (Java and Sumatra), but B. insularum can be distinguished from that species by several characters, including fewer stamens (25 vs 40 stamens), 5-tepalled female flowers (vs 3-tepalled female flowers) and fruit wings with a rounded base and truncate apex (vs fruit wings with cuneate base and truncate apex).