Dissochaeta glabra Merr., J. Straits Branch Roy. Asiat. Soc. 76: 101. 1917.

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

20. Dissochaeta glabra Merr., J. Straits Branch Roy. Asiat. Soc. 76: 101. 1917.

Diplectria glabra (Merr.) M.P.Nayar in Veldkamp et al., Blumea 24: 421, fig. 4B. 1979.

Diplectria glabra (Merr.) M.P.Nayar ssp. glabra : Veldkamp et al., Blumea 24: 421, fig. 4B. 1979.

Diplectria glabra (Merr.) M.P.Nayar var. glabra : J.F.Maxwell, Gard. Bull. Singapore 33: 313. 1980.

Type.

Malaysia. Sabah: Kalabakan, Pinajas River, 20 m elev., 8 Oct 1916, A. Villamil 242 (lectotype, designated here: PNH [PNH32349, image seen]!; isolectotypes: K!, US [US00120530, image seen]!).

Description.

Climbing up to 15 m in height. Branchlets terete, 4-5 mm in diameter, glabrous; nodes swollen, with prominent annular crest-like interpetiolar ridge, often with bristle hairs; internodes 6-8.5 cm long. Leaves: petioles terete, 7-10 mm long, furfuraceous and dorsally with bristle hairs; blades ovate to ovate-oblong, 9-16 × 4.5-8 cm, subcoriaceous, base rounded to shallowly subcordate, margin entire, apex acuminate, tip 0.5-0.8 cm long; nervation with 1 or 2 pairs of lateral nerves and 1 pair of intramarginal nerves; adaxially glabrous, abaxially glabrous, basally with a pair of glandular patches. Inflorescences terminal, up to 90 cm long, many-flowered; main axis angular, glabrous or sparsely covered with stellate hairs; primary axes up to 80 cm long with 7-10 nodes, secondary axes 8-20 cm long with 5-7 nodes, tertiary axes up to 6 cm long with 1-3 nodes, quarternary axes if developed 1-3 cm long with 1 or 2 nodes, quinternary axes when developed up to 0.5 cm with 1 node; bracts linear, 4-5 mm long, caducous, stellate puberulous; bracteoles subulate, ca. 1 mm long, densely covered with stellate hairs; pedicels stellate puberulous, 3-5 mm long in central flowers, 1-2 mm long in lateral flowers. Hypanthium cyathiform-tubular, 4-6 × 2-3.5 mm, glabrous or sparsely covered with stellate hairs; calyx lobes truncate, ca. 0.5 mm long, apex with 4 minute points, purplish; petal bud conical, 1-5 mm long; mature petals suborbicular, 3-6 × 3-4.5 mm, reflexed, base clawed, apex acute, white purplish or purple. Stamens 8, unequal, filaments flattened, straight; alternipetalous stamens staminodial, with 3-5 mm long filaments, anthers rudimentary, slender, terete, thecae 0.5-2 mm long, basal crest triangular, 0.75-2 mm long, thin, apex acute, base emarginate or hastate, lateral appendages prolonged from the theca vestige, paired, filiform, 3-6 mm long; oppositipetalous stamens with 4-6 mm long filaments, anthers thick, curved, hook-shaped or S-shaped, thecae 5-6 mm long, yellow, basal crest triangular, 0.3-2 mm long, erose to bifid, lateral appendages ligular with bifid apex, 0.5-1 mm long. Ovary half to ¾ of hypanthium in length, apex glabrous; style 8-12 mm long, curved at the end, slender, glabrous; stigma minute, capitate; extra-ovarial chambers 4, oppositipetalous, extending from ⅓ to the middle of the ovary. Fruits subglobose to urceolate, 4-7 × 4-5 mm, glabrous, slightly 8-lined; calyx lobe remnants persistent. Seeds ca. 0.5 mm long.

Distribution.

Borneo.

Note.

Within the genus, D. glabra has the longest and most robust inflorescences (up to 90 cm long) with up to 5 degrees of ramifications, but it has smaller flowers. Due to the flowers and stamens, this species closely resembles D. conica and D. papuana . The glabrous appearance and the glandular patches at the leaf base below are similar to D. beccariana , which is also endemic to Borneo, but differs in the shape of the alternipetalous stamens.