Begonia leuserensis M.Hughes, 2015

Hughes, Mark, Girmansyah, Deden & Ardi, Wisnu Handoyo, 2015, Further discoveries in the ever-expanding genus Begonia (Begoniaceae): fifteen new species from Sumatra, European Journal of Taxonomy 167, pp. 1-40 : 25-27

Begonia leuserensis M.Hughes sp. nov. § Platycentrum

urn:lsid:ipni.org:names:77151647-1

Figs 2 , 12

Diagnosis

Differs from B. teysmanniana Miq.(Tebbit) ( Tebbitt & Dickson 2000) in being a lower growing plant (c. 30 cm tall, not c. 60–80 cm) with lobed leaves (not entire) having dense red hairs on the leaf veins (not white sparsely puberulent), and differs from B. areolata Miq. ( Miquel 1855) in having leaves which are smooth above (not densely bullate). Begonia leuserensis differs from both in having 6 (not 5) tepals in the female flowers.

Etymology

The epithet is derived from the type locality of Gunung Leuser National Park, to where the species is endemic.

Type

SUMATRA: Aceh, Gunung Leuser Nature Reserve, Air Panas, 517 m, 19 Mar. 2008, Wilkie, Hughes, Sumadijaya, Rasnovi, Marlan & Suhardi PW 791 (holo-: BO; iso-: E).

Additional material

SUMATRA: Aceh, Gunung Leuser Nature Reserve, Air Panas, 433 m, 18 Mar. 2008, Wilkie et al. PW 778 ( BO, E, SING); Aceh, Gunung Leuser Nature Reserve, Bukit Ketambe, 800 m, 16 Mar. 2008, Wilkie et al. PW 739 ( BO, E, SING).

Description

Repent caulescent herb on earth banks, c. 30 cm tall. Stem with dense red short fleshy hairs, becoming nearly glabrous with age, rhizomatous at base with short internodes <1 cm long, becoming longer (to c. 25 cm long) on flowering stems. Stipules persistent, with fine hairs, denser at the base, lanceolate, 2 × 1 cm, apex long acuminate. Leaves: petiole 4–25 cm long, terete, the longer petioles being borne on the rhizomatous part of the stem, densely red hairy; lamina asymmetric, broadly ovate, lobed, divided up to ½ the way to the midrib, 8–18 × 5–14 cm, basifixed, base cordate, sinus 1–5 cm deep, upper surface glossy, nearly glabrous except for a few short fleshy hairs, under surface with dense red short hairs on the veins; margin denticulate, sparsely hairy. Inflorescences terminal, subtended by a pair of leaves, cymose, with c. 10 flowers, protandrous, bisexual; primary peduncle 8–12 cm long, red hairy; bracts: lanceolate, basal pair fused, tipped with a fringe of several points, 1–3 cm long, hairy at the base externally, bracts in the rest of the inflorescence much smaller. Male flowers: pedicel 15 mm long, hairy; tepals 4, outer 2 tepals ovate, 20 × 15 mm, white, red hairy externally, entire, inner 2 tepals elliptic, 14 × 7 mm, white, glabrous; androecium with c. 100 stamens; filaments subequal, shorter on the basal stamens, up to 1.5 mm long, anthers 1.5 mm long, ellipsoid, wider at the apex, connective extended slightly, rounded. Female flowers: pedicel 15 mm long, hairy; ovary green, with dense short hairs, total size including wings 15 × 22 mm; capsule ellipsoid, 2-locular, placentae unknown; wings 3, unequal, one large and two smaller, rounded-triangular; tepals 6, outer 3 ovate-lanceolate, white, 15 × 9 mm, red or white hairy externally, inner 3 elongate-obovate, glabrous; stigmas 2, bifid, greenish yellow, surface convolute. Fruit usually borne in pairs, recurved on a stiff pedicel c. 2.5 cm long; largest wing triangular, 2 cm long, outline slightly curved, thick and corky, smaller two wings forming a splash cup, triangular, 12 mm long; apex truncate.

Distribution and habitat

Endemic to Gunung Leuser National Park ( Fig. 2 ), found on steep slopes on the forest floor at 400–800 m altitude, where it grows in leaf litter around rotting logs and at the base of trees.

Conservation status

Currently the montane forests in Gunung Leuser National Park are not under pressure, and the two known locations for the species are in the centre of the reserve. It seems likely that the species may be found on other nearby peaks at similar altitudes. We consider an IUCN category of Least Concern to be appropriate.

Figures

Fig. 2. Map of Sumatra showing the full known species distributions based on collection localities. Each point may represent more than one collection.

Fig. 12. Begonia leuserensis M.Hughes sp. nov. A. Habit. B. Male flower back view. C. Male flower. D. Female flower. E. Lobed leaf. A–D from Air Panas of the type collection Wilkie et al. PW791; E from PW778. Scale bars on insets: B–D = 1 cm; E = 10 cm.