| Original Botanical Description or Link to | Two new species of Begonia L. (Begoniaceae) from central Laos
Keooudone SOUVANNAKHOUMMANE, Soulivanh LANORSAVANH, Vichith LAMXAY: Begonia khammouanensis Souvann. & Lamxay, sp. nov.
Som Koung Bai Boua [Lotus leaf begonia] Sect. Diploclinium.
A distinct species, closest to Begonia crassula Aver.
in having succulent leaves, the same number of tepals in
male and female flowers and bifid, axile placentae. It
differs in being stemless (not succulent caulescent), and
in having a symmetric reniform lamina, (not strongly
asymmetric and narrowly ovate), and lanceolate and
acuminate apex of tepals (not reniform and rounded apex
of tepals). − Type: Laos, Khammouan province,
Boualapha district, Hin Nam No National Protected
Area, 17°26'35.6"N 105°47'30.2"E, 259 m,, 10 October
2017, Lamxay et al. HNN 138 (holo HNL, iso FOF, E,
SING).
Monoecious rhizomatous herb, 30–50 cm tall.
Rhizomes stout, 3–12 cm long, 6–10 mm in diam., erect
near apex, c. 2 cm tall, with numerous fibrous roots.
Leaves arranged in rosette-like cluster at the top of
rhizome; petiole 5–24 cm long, puberulous to
glabrescence, dark red at base, paler red-green toward
apex; lamina succulent, symmetrical, reniform, 4–6.5 ×
6–8.6 cm, base shallowly cordate, apex rounded, margin
undulate; adaxial surface, glossy, dark green, abaxial
surface pale green, glabrous on both surface; venation
palmate, veins 5–7, prominent beneath. Stipules
persistent, herbaceous, ovate to triangular-cuneate, 14–
25 × 6–12 mm, apex acute to acuminate, margin entire,
outside puberulous, inside glabrous, pink to lightly
green. Inflorescences compound cymes arising from top
of rhizome, branched up to 4 times, bisexual, 35–40 cm
long, staminate flowers distal and pistillate flowers
basal, protandrous; peduncles 20–36 cm long, terete,
with glandular hairs, dark red, glossy. Bracts ovate, 3–8
× 2–4 mm, apex acute, margin entire, glandular hairy
outside, pale green. Staminate flowers: pedicels 10–12
mm long, erect or occasionally ascending, sparsely
glandular hairy, dark red; tepals 2, lanceolate, 14–16 ×
6–10 mm, apex acuminate, outside surface with
glandular hairs, inside surface glabrous, pink flush inside
and outer part darker; stamens c. 15, bright yellow,
filaments clustered at the base, c. 2.5 mm, free 0.7–1 mm
long, anthers oblong-elliptic, 0.8–1 mm long, dehiscing
by longitudinal slits near the tip. Pistillate flowers:
pedicels 12–18 mm long, with glandular hairs, dark red;
tepals 4, outer 2 lanceolate, 12–15 × 8–12 mm, margin
entire, apex acuminate, outside surface sparsely
glandular hairy, inner 2 elliptic-lanceolate, 6–9 × 3–6
mm, margin entire, apex acuminate, glabrous, same
colour as staminate flowers; ovary lightly red or pink,
with 3 locular, with 3 wings, abaxial one narrowly
rectangular, lateral 2 small ridges; 3-locular,
placentation axillary, 2 branches per locule; styles 3,
connate at the base into common stalk, dark yellow;
stigmatic band U-shaped and minutely papillose;. Fruits
capsules, elliptic-oblong, 12–15 × 7–12 mm (including
wings); locules subglobose, 3–4 × 3–4 mm, abaxial wing
narrower, narrowly rectangular, curved along length of
capsule, c. 14 mm long, 3.5–4 mm wide, 2 lateral wings
reduced to ridges, wide at base, glossy, with glandular
hairs, pale red to pink, drying pale brown. Seed
numerous, elliptic-oblong, 0.3–0.4 × c. 0.1 mm, testa
reticulate, brown.
Distribution. Endemic to central Laos; Hin Nam No
National Protected Area with three additional populations
in Boualapha district, Khammouan province.
Habitat and ecology. This species occurs on wet
steep rocky slopes in limestone mixed deciduous forest
and dry evergreen forest at 230-400 m elevation.
Flowering September to October; fruiting October to
January.
Notes. This species is distinct in its glabrous and
glossy symmetrical reniform lamina, and petioles and
inflorescences with glandular hairs. The specific epithet
khammouanensis refers to the type locality.
Proposed IUCN category. VU D2. This new taxon
is only known from two locations in very limited area
and few populations. |
