Begonia masarangensis Irmsch. [§ 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 : 28-30

12. Begonia masarangensis Irmsch. [§ Petermannia ], Bot. Jahrb. Syst. 50: 368 (1913).

– Type: Indonesia, Sulawesi, Masarang , 23 iv 1894, K.F. & P.B. Sarasin 269 (holotype B [B100217759], isotype K [K000761116]). Figure 9 .

Perennial, small, monoecious herb, erect, c. 20–25 cm tall. Stem erect, few-branched; internodes 1–4 cm long, slightly swollen at the nodes, brownish-reddish, densely hairy with bristly hairs. Leaves basifixed, alternate; stipules persistent, 5–8 × 2.5–4.5 mm, anisophyllus, ovate, with an abaxially slightly prominent midrib, apex narrowed into bristle projecting up to 6 mm, margin entire, cream-coloured, abaxially hairy; petioles 0.6–3 cm long, terete, not channelled, concolorous with the stem, densely hairy; lamina 3.7–9.5 × 2.5–4.5 cm, asymmetrical, elliptic, base cordate and lobes not or just slightly overlapping, apex acuminate, margin biserrate, adaxial surface green, with red veins, densely covered with strigose, simple or sometimes branched hairs, abaxial surface brownish, hairy; venation pinnate, secondary veins craspedodromous. Inflorescences protogynous, female inflorescences basal to male or sometime solitary; female inflorescences 1-flowered, peduncles c. 10 mm long, bract persistent, c.5 × 1–2 mm, elliptic; male inflorescences simple monochasia with up to 10 flowers, peduncle c. 6 mm, hairy, bracts caducous. Male flowers: pedicels 9–16 mm long, white-cream, hairy; tepals 2, white, 12–17 × 17–22 mm, broadly ovate, base slightly cordate, apex rounded, outer surface hairy; androecium of 22–25 stamens, yellow, filaments up to c. 1 mm long, slightly fused at the very base, anthers up to c. 1 mm long, oblong to narrowly obovate, dehiscing through unilaterally positioned slits that are c.1/2 as long as the anthers. Female flowers: pedicels c. 7 mm long, pink, densely hairy; tepals 5, white, unequal, four larger c.15 × 17 mm, broadly ovate, one smaller 12–15 × 5–10 mm, obovate, adaxially hairy; ovary (excluding wings) 8 × 4.5 mm, ellipsoid, pale green with red longitudinal line, densely hairy, locules 3, placentation axile, placentae bilamellate, wings 3, subequal to unequal, pale green, base rounded, apex truncate, up to 9 mm at the widest point (apically or subapically); style c. 6 mm long, basally fused, 3-branched, each stylodium bifurcate in the stigmatic region, stigmatic surface a spirally twisted papillose band, orange. Fruits not seen.

Distribution. Indonesia: endemic to Sulawesi, North Sulawesi Province (eastern North biogeographical region), Gunung Masarang (see Figure 2 ).

Habitat. Disturbed or secondary upland to montane forest at 1000–1800 m elevation, in full shade.

Proposed IUCN conservation category. Critically Endangered ( CR), B1 ab(iii)+B2ab(iii). Begonia masarangensis is known from only two collections from a small forest remnant at its type locality, Gunung Masarang , Tomohon. The area is not legally protected, and currently most of the forest formerly surrounding the type locality has been converted into agricultural land. In combination with the very small AOO (4 km 2), this indicates that the species should be considered Critically Endangered ( IUCN Standards and Petitions Subcommittee, 2019).

Additional specimens examined. INDONESIA. Sulawesi. Northern arm of Sulawesi. Eastern North Sulawesi: Minahassa , top of G. Masarang, 10 i 1949, Koorders 16240b ( K) ; 20 ii 2008, M. Ardiyani, A.D. Poulsen & Ale 105 ( BO) ; 2 ii 2019, W.H. Ardi et al. WI400 ( BO, FIPIA) .

See notes under Begonia hispidissima .

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 9. Begonia masarangensis. A and B, Habit; C, stipule; D, male inflorescence; E, male flowers (front view); F, female flower (side view); G, female flower (front view); H, ovary (cross-section of middle part). A–H from W.H. Ardi WI400. Photographs: W. H. Ardi.