Begonia mendumiae M.Hughes [§ Petermannia

Ardi, W. H. & Thomas, D. C., 2022, SYNOPSIS OF BEGONIA (BEGONIACEAE) FROM THE NORTHERN ARM OF SULAWESI AND SANGIHE ISLAND, INDONESIA, INCLUDING THREE NEW SPECIES, Edinburgh Journal of Botany 79 (405), pp. 1-50 : 30-32

13. Begonia mendumiae M.Hughes [§ Petermannia ], Edinburgh J. Bot. 62: 196 (2006).

– Type: Indonesia, Sulawesi, Gorontalo, Gunung Ali , 28 iv 2002, M. Mendum et al. 240 (holotype E [E00163221], isotype K [K001235163]). Figure 10 .

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

Habitat. The species was observed growing on various substrates (soil, limestone rock, and other rock types) in secondary lowland to hill forest and even in a forest remnant in a cocoa plantation, in full to half shade, at 20–600 m elevation.

Proposed IUCN conservation category. Near Threatened (NT). Begonia mendumiae is endemic to Sulawesi and relatively widespread on the island (EOO, 45,962 km 2; AOO, 32 km 2), mostly occurring in disturbed lowland forest or limestone forest habitats. However, its known range does not include any legally protected areas in Sulawesi. Consequently, we assess this species as Near Threatened ( IUCN Standards and Petitions Subcommittee, 2019).

Additional specimens examined. INDONESIA. Sulawesi. Northern arm of Sulawesi. Western North Sulawesi: Palu-Oti Road , 3 vii 1979, M.M.J van Balgooy 3597 ( L) ; Donggala Regency, Batusuya , 10 viii 2018, W.H. Ardi et al. WI316 ( BO, KRB, SING) . Central North Sulawesi: Gorontalo: Albert s.n ( BO) .

Central Sulawesi Province: Poso Regency, Bancea , 2 viii 2018, W.H. Ardi et al. WI281 ( BO, KRB, SING) ; Poso Regency, Pesisir Utara Poso : 15 ii 2019, W.H. Ardi et al. WI429 ( BO, KRB, SING) ; 15 ii 2019, W.H. Ardi et al. WI434 ( BO, KRB, SING). Donggala Regency, Air Terjun Pangansitoli, 5 iii 2020, W.H. Ardi et al. WI690 ( BO, KRB, SING). West Sulawesi Province: Pasang Kayu Regency, Gumbasalu Cave , 3 iii 2020, W.H. Ardi et al. WI686 ( BO, KRB, SING) .

Based on observations in the field, Begonia mendumiae is morphologically highly variable, particularly regarding the indumentum density, leaf size and coloration, and ovary shape both among individuals in populations and among different populations. However, most generative characters are more stable, allowing clear identification of the species. Individuals from the Poso Pesisir Utara population have larger leaves, up to 21 × 14 cm, whereas distinctly smaller leaves (c.15 × 10 cm) are found in the other populations. Most of the populations show several variable characters such as adaxial leaf lamina colour, which can be reddish-dark green with irregular silvery variegation or light green without any variegation; short (up to 5 mm long) or long (up to 50 mm long) female inflorescence peduncles; 1- or 2-flowered female inflorescences; ovate or lanceolate female flower tepals; ellipsoid or cylindrical ovaries (without wings); and narrow or wider ovary and fruit wings, which can be rounded or cuneate at the base.

Figures

Figure 2. Distribution maps of Begonia species occurring on the northern arm of Sulawesi. Distribution points are from georeferenced collections from major herbarium collections (B, BO, E, K, KRB, L, SING), the Begonia Resource Centre (Hughes et al., 2015–) and the Sulawesi Begonia Data Portal (Thomas et al., 2013, continuously updated).

Figure 10. Begonia mendumiae from different locations. A, Cultivated from type locality, Gorontalo (M. Mendum et al. 240); B, Pangansitoli Waterfall, Donggala, C. Sulawesi (W.H. Ardi WI690); C, Pesisir Utara Poso, C. Sulawesi (W.H. Ardi WI429); D, Batusuya, Donggala, C. Sulawesi (W.H. Ardi WI316); E, Bancea, Poso, C. Sulawesi (W.H. Ardi WI281); F, Gumbasalu Cave, Pasang kayu, W. Sulawesi (W.H. Ardi WI686). Photographs: A, Mark Hughes; B–F, W. H. Ardi.