Begonia (sect. Petermannia) chiasmogyna M. Hughes

4.Begonia chiasmogyna M.Hughes [§ Petermannia], Edinburgh J. Bot. 63: 193 (2006). –

Type: Indonesia, Sulawesi, Gorontalo, Gunung Boliohutu, 23 iv 2002, M. Mendum et al. 167 (holotype E [E00163227]).

Distribution. Indonesia: endemic to Sulawesi, North Sulawesi and Gorontalo Provinces (see Figure 2).

Habitat. Stream embankment at 800 m elevation, in full shade.

Proposed IUCN conservation category. Data Deficient (DD). This species is known from three localities: Bogani Nani Wartabone National Park, Gunung Boliohutu, and Gunung Poniki. Although the result of GeoCAT analysis recommend an Endangered status based on the EOO (1064 km 2) and AOO (12 km 2), the forests in the wider area of the three mountains is very poorly collected, and the species will probably also occur deeper in the forested areas. Because more detailed field observations of habitat conditions, population sizes and local abundance at the collection sites are lacking, we currently assess this species as Data Deficient (IUCN Standards and Petitions Subcommittee, 2019).

Additional specimens examined. INDONESIA. Sulawesi. Northern arm of Sulawesi. Central North Sulawesi: Gorontalo, Gunung Boliohutu, 9 iv 2002, M. Mendum et al. 46 (E, K, L); Gunung Boliohutu, 22 iv 2002, M. Mendum et al. 146 (E). Eastern North Sulawesi: Bolaang Mongondow, Dumoga-Bone National Park, Edward Camp, 28 iii 1985, de Vogel & Vermeulen 6790 (E); Bolaang Mongondow, Gunung Poniki, 30 x 2016, S. Barber et al. BAAK13 (BO, E).

Begonia chiasmogyna is similar to B. gambutensis Ardi & D.C.Thomas in terms of the dense indumentum on the vegetative parts and the cymose male inflorescence. In other characters, however, the two species are distinct. Begonia chiasmogyna can be easily differentiated from B. gambutensis by the colour of the indumentum, because the former species has a white indumentum (not red crimson). Other differentiating characters include the number and shape of the tepals of the female flowers: Begonia chiasmogyna has four obtrullate tepals, whereas B. gambutensis has five obovate tepals (Ardi et al., 2014).