Dissochaeta maxwellii (Karton.) Karton., 2018

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

36. Dissochaeta maxwellii (Karton.) Karton. comb. nov. Map 20

Basionym.

Diplectria maxwellii Karton., Kew Bull. 73-23: 1, fig. 1. 2018.

Type.

Malaysia. Sarawak: Kapit Division, Batang Baleh, Nanga Serani, 500 m elev., 4 May 1991, Runi et al. S.63137 (holotype: K [K000566618]!; isotypes: KEP [KEP43526, image seen]!, L [L3908632]!, SAN! [image seen], SAR n.v.).

Description.

Climbing up to 6 m in height. Branchlets terete, angular in the upper branches, ca. 3 mm in diameter, glabrous to sparsely stellate-puberulous; nodes swollen, with distinct interpetiolar ridge, annulum, densely covered with stellate-pubescent hairs and 4-6 mm long, brown, bristle hairs, prominent, ca. 0.1 mm thick at base, narrowing towards the acute tip; annulus 1-2 mm high, brownish; internodes ca. 5-6 cm long. Leaves: petioles terete, 10-12 mm long, densely stellate-pubescent and covered with dense, 4-7 mm long, brown bristle hairs; blades elliptic-oblong, 10.3-12.9 × 3.8-5 cm, membranous, base rounded, margin entire, apex acuminate, tip 1.2-1.5 cm long; nervation with 1 pair of lateral nerves and 1 pair of intramarginal nerves; adaxially glabrous, dark green, abaxially glabrous or stellate-puberulous on midrib and sparsely hairy on lateral veins, light brown. Inflorescences terminal, up to 14.8 cm long, many-flowered; main axis quadrangular, densely stellate-pubescent and sparsely covered with bristle hairs, purplish-green, nodes densely stellate-pubescent and densely covered with 3-5 mm long brown bristle hairs; primary axes ca. 12 cm long with 3 or 4 nodes, secondary axes 1.5-6 cm long with 1 or 2 nodes, tertiary axes 6-8 mm long with 1 node; bracts oblong-lanceolate, 5-7 mm long, densely stellate-pubescent, covered with 3-4 mm brown bristle hairs at the margin; bracteoles oblong, 2-3 mm long, densely stellate-pubescent; pedicels densely stellate-pubescent, purplish, 4-7 mm long in central flowers, 3-3.5 mm long in lateral flowers. Hypanthium tubular, campanulate, 3.5-4 × ca. 2.5 mm, densely pubescent and sparsely covered with glandular bristle hairs in middle and base; calyx lobes truncate, ca. 0.5 mm long, minutely apiculate; petal buds conical, 1-2 mm long, acute; mature petals obovate, 3-4.5 × 2.5-3 mm, apex acute, base clawed, glabrous. Stamens 8, unequal, filaments straight, glabrous; alternipetalous stamens staminodial with 3-4 mm long filaments, anthers reduced, thecae rudimentary, lanceolate, 2-4 mm long, terete, thin, basal crest triangular with erose tip, ca. 1 mm long, lateral appendages absent; oppositipetalous stamens with ca. 3 mm long filaments, anthers clavate, sickle-shaped, curved, thecae 4-5 mm long, glabrous, smooth, basal crest minute, ca. 0.3 mm long, lateral appendages paired, small, ligular, ca. 0.5 mm long. Ovary ⅔ of hypanthium in length, densely pubescent at top; style curved at top, 6-10 mm long, glabrous; stigma minute, inconspicuous; extra-ovarial chambers 4, extending to the middle of the ovary. Fruits globose, 5-8 × 3-6 mm, glabrous, red when ripe; calyx lobe remnants persistent, erect. Seeds ca. 0.5 mm long.

Distribution.

Borneo (Sarawak).

Ecology and habitat.

Sub-montane forest at ca. 500 m elevation.

Vernacular name.

akar kemunting (Kapit).

Note.

A distinct species that resembles D. viminalis in the number and shape of the stamens, but differs in having dense prominent bristle hairs on the nodes, petioles, bracts and bracteoles. Known only from the type from Kapit Division, Sarawak.

Figures

Map 20. Distribution of D. malayana (●), D. marumioides (■) and D. maxwellii (▲).