Begonia halabanensis 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 : 12-13

Begonia halabanensis M.Hughes sp. nov. § Reichenheimia

urn:lsid:ipni.org:names:77151640-1

Figs 2 , 5

Diagnosis

The peltate and succulent leaves are also found in B. kudoensis , however B. halabanensis has a thickly hairy rhizome and petioles (not glabrous), male flowers with 2 tepals (not 4), larger inflorescences (with c. 80 flowers, not c. 40) and fruit with a truncate (not obtuse) apex. The key from couplet 6 onwards deals with all 5 currently described peltate species from Sumatra.

Etymology

The epithet refers to the distribution of the species in Halaban in West Sumatra near Payakumbuh.

Type

SUMATRA: West Sumatra, Pajakumbuh, Halaban, 800 m, 29 Jan. 1950, Meijer 7550 (holo-: L).

Description

Erect acaulescent herb 20–30 cm tall; stem rhizomatous, stout, internodes c. 1 cm long, densely covered in a matted indumentum of reddish brown multi-branched thick hairs c. 1 cm long. Stipules lanceolate, stout, 2–3 × 1.5 cm, fibrous, persistent, with thick, long hairs. Leaves: petiole c. 20 cm long, cross section unknown, with quite dense 5 mm long hairs; lamina peltate, point of petiole attachment placed to within 3 cm of the margin, suborbicular, 10–15 × 10–15 cm, thick and succulent, base rounded, margin entire in outline, with evenly spaced 2 mm long stiff rounded teeth that are recurved underneath, margin also with a fringe of 5 mm long hairs, apex acute, underside with many pale dots of stomatal clusters, venation palmate, main veins 8, quite widely spaced over most of the lamina. Inflorescences axillary, c. 40 cm long and exceeding the leaves, cymose, many-flowered, branching c. 8 times, bisexual, protandrous; bracts elliptic, minute, glabrous, entire, c. 2 × 1.5 mm towards the terminal branches, basal pair not seen. Male flowers: pedicel 5 mm long, slender, glabrous; tepals 2, orbicular, entire, glabrous, c. 8 × 8 mm; androecium globose, symmetric, with c. 40 stamens, filaments unequal, fused at base, shorter to slightly longer than the anther, anther 0.75 mm long, ellipsoid-obtriangular, dehiscing through short slits near the apex, apex retuse, not hooded. Female flowers unknown. Fruits pendent on a 15–20 mm long hair-like pedicel, borne in a cyme of c. 50, total size 9 × 21 mm; capsule globose, 6 mm in diameter, three-locular, placentae entire; wings 3, subequal, 8–10 × 8–9 mm, tips rounded; apex obtuse.

Distribution and habitat

Found on limestone, endemic to the type locality in Halaban, West Sumatra ( Fig. 2 ). The thick fleshy leaves and densely hairy rhizome of this very distinctive species imply adaptation to dryer habitats. Known only from the type.

Conservation status

The distribution of limestone habitat in the Halaban area is not very well known, and the exact location of the type collection is not clear. Whether the species is already extinct, or in fact thriving in a naturally small population needs further fieldwork in the Halaban region; we assess B. halabanensis to be Data Deficient ( IUCN 2012).

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. 5. Begonia halabanensis M.Hughes sp. nov. A. Holotype [Meijer 7550 (L)]. B. Portion of leaf lamina underside showing margin hairs and recurved teeth. C. Anthers. D. Fruit. E. Male flower. Drawings by M. Hughes.