Dissochaeta atrobrunnea G.Kadereit, Edinburgh J. Bot. 63(1): 4, fig. 1. 2006.

Kartonegoro, Abdulrokhman, Veldkamp, Jan Frits, Hovenkamp, Peter & Welzen, Peter van, 2018, A revision of Dissochaeta (Melastomataceae, Dissochaeteae), PhytoKeys 107, pp. 1-178 : 1

5. Dissochaeta atrobrunnea G.Kadereit, Edinburgh J. Bot. 63(1): 4, fig. 1. 2006. Map 5

Type.

Indonesia. Central Kalimantan: Barito Ulu, Project Barito Ulu Base Camp, 1 Jun 1990, K. Sidiyasa PBU 229 (holotype: E [E00225106]!; isotypes: BO [BO0009659]!, K [K001089634]!, L [L.2542233]!).

Description.

Climbing up to 20 m in height. Branchlets terete, 4-6 mm in diameter, densely covered with stellate hairs and dark red-brown bristle hairs; nodes swollen, with interpetiolar ridge, thickly covered with stellate hairs and dark-red bristle hairs thickened at base; internodes 3.5-6 cm long. Leaves: petioles terete, 5-9 mm long, densely covered with stellate hairs and bristles; blades ovate, 8-11 × 4-7 cm, subcoriaceous, base cordate, margin entire, apex acuminate, densely bristly, tip 0.5-1 cm long; nervation with 2 pairs of lateral nerves and 1 pair of intramarginal nerves; adaxially glabrous with prominent nerves, abaxially with sparsely brown stellate hairs, more dense on midrib and with bristle hairs. Inflorescences terminal (many-flowered) and axillary (9-15 flowers), up to 20 cm long, up to 7 cm long when axillary; main axis angular, flattened at upper side, densely covered with stellate hairs and bristles; when terminal with primary axes up to 16 cm long with 6 or 7 nodes, secondary axes 5-6 cm long with 2 or 3 nodes, tertiary axes 0.8-1 cm long with 1 node; when axillary with primary axes, up to 5 cm long with 2 or 3 nodes, secondary axes up to 1 cm long with 1 node, tertiary axes not developed; bracts elliptic, 10-15 × 3-5 mm, densely covered with bristle hairs; bracteoles subulate, 7-9 × 1-2 mm, densely covered with bristle hairs; pedicels densely covered with stellate hairs and bristles, 2-3 mm long in central flowers, ca. 1 mm long or subsessile in lateral flowers. Hypanthium campanulate, 6-8 × 3-4 mm, densely covered with stellate hairs and bristle hairs; calyx lobes triangular, 1-2 mm long, densely covered with bristle hairs; petal bud conical, 5-6 mm long, apex bristly; mature petals ovate, 10-12 × 5-6 mm, glabrous, reflexed, base clawed, apex obtuse, white with purple flush or pinkish. Stamens 8, subequal, filaments curved sideways; alternipetalous stamens with ca. 9 mm long filaments, anthers slightly curved, sickle-shaped, thecae 8-9 mm long, pedoconnective 3-4 mm long, basal crest minute, lateral appendages paired, filiform, up to 6 mm long; oppositipetalous stamens with ca. 7 mm long filaments, anthers S-shaped, thecae 8-9 mm long, basal crest absent, lateral appendages paired, filiform, 5-6 mm long. Ovary ⅔ of hypanthium in length, apex thickened, bristly; style slightly curved when mature, 7-8 mm long; stigma minute; extra-ovarial chambers 8, the 4 alternipetalous ones extending to the base of the ovary, the 4 oppositipetalous ones extending to about the lower third of the ovary. Fruits urceolate, ca. 12 × 5-6 mm, covered with stellate hairs and dark red-brown bristles; calyx lobe remnants persistent. Seeds ca. 0.5 mm long.

Distribution.

Borneo (Central Kalimantan).

Ecology and habitat.

Primary and secondary lowland dipterocarp forest on swampy soil and in open areas at ca. 150 m elevation.

Note.

Dissochaeta atrobrunnea is known only from three collections from lowland dipterocarp forest in Central Kalimantan, Indonesia. The species resembles D. alstonii from North Sumatra by its dense bristles found all over the branchlets, petioles and hypanthium, but differs by having longer bristles and a larger hypanthium and fruits. The appearance of the vegetative organs sometimes resembles Macrolenes hirsuta (Cogn.) J.F.Maxwell, which is different in its flowering organs ( Kadereit 2006).

Specimens examined.

INDONESIA. Central Kalimantan: Barito Ulu, 1 Jun 1990, K. Sidiyasa PBU 229 (BO, E, K, L); Ibid., Trail Jalang Babang, 18 Jun 1990, C.E. Ridsdale PBU 81 (L); Kahayan River, South of Tumbang Sian, 150 m, 1 May 1988, J.S. Burley & Tukirin 852 (BO, K, L).

Figures

Map 5. Distribution of D. atrobrunnea (●), D. bakhuizenii (■) and D. barbata (▲).