Begonia ltahensis Girm.

Girmansyah D. 2017. Two new species of Begonia (Begoniaceae) from Long Duhung, Berau Regency, East Kalimantan, Borneo Island, Indonesia. Kew Bulletin 72:3. DOI 10.1007/S12225-016-9665-2

Type

Type: Indonesia, East Kalimantan, Berau Regency, Kelay Distr., Long Duhung Village, Unggun Forest along Ltah R., 100 - 150 m alt., 2 May 2015, Deden Girmansyah Deden 2092 (holotype BO!).

Habit

Cane-like begonia to 50 cm tall, sparsely covered with pale brown hairs

Stem

Stems dark red to brownish red, 7 - 10 mm thick, internodes, 3 - 6 cm apart, succulent, unbranched, slightly swollen at the nodes, rooting at base

Stipules

Stipules reddish at base and green towards the apex, narrowly triangular, c. 3.5 x 1 cm, hairy along the middle, margin entire, apex acuminate, persistent

Leaves

Leaves alternate, oblique, distant, held more or less vertically; petiole dark red to brownish red, 10 - 20 cm long, sparse hairs, getting rather dense near the base of lamina, canaliculate above; lamina rather grooved above with scattered short hairs near the base through the vein and prominent beneath with scattered hairs along the vein, asymmetric, broadly ovate, 20 - 27 x 11 15 cm, margin slightly dentate, apex acute; venation palmate-pinnate, veins reddish at base and becoming pale green near the apex, slightly hairy near the base, 2 - 3 pairs along the midrib, 2 veins in basal lobe, impressed above, prominent beneath

Inflorescences

Inflorescences protogynous, axillary; male and female inflorescences separate, a single or pair of female flowers at the lower stem or rhizome, male inflorescences with many flowers, cymes, total length of inflorescences 2.5 – 3 cm long, peduncle c. 1.5 cm; bracts in female inflorescences: pale green, glabrous, 6 - 8x4- 5 mm, margin entire, ovate, persistent; male inflorescences: rounded to broadly obovate, margin dentate with rounded glands; bracteoles in male flowers similar to bract, pale green, glabrous, margin dentate with unusual glands at the end of teeth, broadly obovate to rounded, c. 3 x 2 mm, persistent

Flowers

Female flowers pedicel reddish, 10 - 20 mm long, with thinly scattered hairs; ovary pink with scattered hairs near the base, 10 - 15 x 10 - 13 mm, wings 3, subequal, locules 3, placentas 2 per locule; tepals 5, not isomorphic, pinkish, lanceolate, 9 - 10 x 4 - 5 mm with scattered hairs at the base, margin entire, apex rounded; styles 3, yellow, wide Y-shaped, c. 5 mm long, divided to base; stigma yellow, papillose, forming a continuous twisted band Male flowers pedicel light red, 10 - 13 mm long c. 5 mm long, glabrous; tepals 2, white and rosy at base through the middle, rounded to broadly ovate, c. 5 x 5 mm, margin entire, apex rounded; stamens c. 20, clustered not globose, filaments yellow, c. 0.5 - 1.2 mm long; anthers yellow, oval to oblong, c. 1 - 1.2 mm long, apex emarginate

Fruits

Fruit single or pairs on the lower stem or rhizome, 11 - 12 x 10 - 11 mm, pale green, sparsely hairy at base, locules 3, wings 3, subequal, dehiscing between the locule and wing; pedicel pendent, reddish brown, c. 2 cm long, sparsely hairy

Seeds

Seed barrel-shaped, ovoid to ellipsoid, 0.3 - 0.35 mm long, collar cells more than a half the seed length

Distribution

Only known from one location in East Kalimantan, in the Indonesian part of Borneo.

Ecology

Terrestrial herb from a hillside in mixed lowland dipterocarp forest, frequently along stream margins in damp places, alt. 141 m.

Conservation

Begonia ltahensis is only known from one locality. It is likely to be found in similar habitats in Borneo and more extensive collections from the region are needed to confirm its distribution. The conservation status of Data Deficient (DD) is most appropriate for this species (IUCN 2012).

Note

Begonia ltahensis is similar to B. calcarea Ridl. in erect habit, leaf shape, number of female flowers and fruits but differs in the male inflorescence, male and female tepal colour and the tepal margins in male and female flowers. The species is named after the type locality “Ltah” a small stream at Unggun forest in Berau Regency, East Kalimantan, Indonesia. Similar to Begonia calcarea Ridl. in habit, female flowers from leaf axils or from the rhizome and the number of female flower tepals. Differs in erect stem, male inflorescence cymes, pinkish female tepal colour, and tepal margin entire.