Begonia olivacea Ardi sp. nov. §. Reichenheimia urn:lsid:ipni.org:names:77151649-1 Figs 4, 14 Diagnosis The nearest species morphologically to Begonia olivacea is B. nurii Irmsch. (Irmscher 1929) from Kelantan in Peninsular Malaysia, the former differing in being a slightly smaller plant (leaves 2.7–4.5 × 2.6–3.7 cm, not c. 4 × 4–6 cm), having 3 (not 2) tepals in the female flowers, sparsely hairy petioles (not red-woolly), and duller green leaves (Kiew 2005). Also similar is B. droopiae Ardi (Ardi & Hughes 2010) from limestone in West Sumatra, which has more asymmetric leaves with darker variegation, and which is smoothly bullate between the veins (not mostly flat). See under B. simolapensis for a comparison with that species. Etymology The epithet reflects the dull greenish brown olive colour of the leaves. Type SUMATRA: North Sumatra Province, Leuser National Park, Simolap, 250 m, 9 Jul. 2011, Carmen Puglisi 230 (holo-: BO; iso-: E). Additional material SUMATRA: Aceh, Gajolandan, 600 m, 25 Feb. 1937, Van Steenis 9273 (BO); ibid., 600 m, 26 Feb. 1937, Van Steenis 9321 (L); Ketambe Research Station, Gunung Leaser Nature Reserve, 300–350 m, 9 Jun. 1979, de Wilde & de Wilde Duyfjes 18002 (L). Description Lithophytic acaulescent herb. Stem rhizomatous, internodes very short c. 1–2 mm long.Stipules persistent, with 2 mm long hairs on the keel, 10 mm long, narrowly oblong, with a 3.5 mm long filiform extension at the apex. Leaves: petiole 2.5–9 cm long, terete, sparsely hairy; lamina suborbicular, asymmetric, 2.7–4.5 × 2.6–3.7 cm, basifixed, base cordate with lobes sometimes slightly overlapping, abaxially mid green on the veins, dark purplish green between, occasionally all green with a faint purplish tinge between the veins, glabrous, slightly prominent between the veins, coriaceous, adaxially with sparse hairs on veins only, primary veins 5–7, margin crenate and fringed with sparse short hairs and recurved stiff teeth at the end of the veins, apex rounded. Inflorescences axillary, cymose, branching 2 times, few flowered, bisexual, protandrous; peduncle 7.5–10.5 cm long, glabrous,; bracts minute, caducous. Male flowers: pedicel 10–15 mm long, glabrous; tepals 4; outer tepals broadly ovate, 7–8 × 6–7 mm, white, glabrous, slightly cordate at the base becoming truncate when open, margin entire; inner tepals narrowly obovate or elliptic, c. 7 × 2 mm, white; androecium pale yellow, symmetric, globose, on a 1.5 mm long column; stamens 35–40. Female flowers: pedicel c. 14 mm long; ovary green, glabrous, total size including wings c. 5 × 11 mm; capsule ellipsoid, 5 × 3 mm, locules 3, placentae entire; wings 3, equal, rounded at base and sub cuneate at the apex, widest point at the middle, c. 4 mm; tepals 3; outer tepals 2, 6.5–7 × 6 mm, sub orbicular, white, glabrous; inner tepal 1, c. 5 × 2.5 mm, elliptic; stigmas 3, pale yellow-green, forked and once spirally twisted, caducous. Fruit recurved on a 17 mm long pedicel; total size c. 5 × 16 mm including the wings, wings 5 mm wide; apex obtuse. Distribution and habitat North Sumatra and Aceh, Gunung Leuser National Park (Fig. 4). This species grows in meagre, dusty soil on limestone rock at 250–600 m altitude. Conservation status The limestone habitat of the Gunung Leuser National Park in the Simolap area where this species occurs is relatively intact. As long as this remains the case, B. olivacea can be considered as belonging to the IUCN category of Least Concern.

Published as part of Hughes, Mark, Girmansyah, Deden & Ardi, Wisnu Handoyo, 2015, Further discoveries in the ever-expanding genus Begonia (Begoniaceae): fifteen new species from Sumatra, pp. 1-40 in European Journal of Taxonomy 167 on pages 29-31, DOI: 10.5852/ejt.2015.167, http://zenodo.org/record/3805815