Dissochaeta rubiginosa Stapf, J. Linn. Soc., Bot. 42: 79. 1914.

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

47. Dissochaeta rubiginosa Stapf, J. Linn. Soc., Bot. 42: 79. 1914. Map 25

Type.

Malaysia. Sabah: Ranau, Mount Kinabalu, Gurulau Spur, 5500 ft elev., Feb 1910, L.S. Gibbs 3977 (holotype: K [K000859491]!).

Description.

Climber. Branchlets terete, 3-5 mm in diameter, covered with densely stellate-furfuraceous hairs; nodes swollen, interpetiolar ridge raised; internodes 3.5-10 cm long. Leaves: petiole terete, 10-15 mm long, densely stellate-furfuraceous; blade elliptic-oblong or oblong, 7-11 × 2-4.8 cm, membranous, base rounded or cuneate, margin entire, apex acuminate, tip 0.5-1 cm long; nervation with 1 pair of lateral nerves and 1 pair of intramarginal nerves; adaxially glabrous, dark glossy green, abaxially brown, stellate-furfuraceous. Inflorescences terminal and in the upper leaf axils, cymous, with many flowers, 17-25 cm long; main axis angular densely stellate-furfuraceous; primary axes up to 23 cm long with 5-7 nodes, secondary axes 2-9 cm long with 2-5 nodes, tertiary axes 0.7-1.8 cm long with 1 or 2 nodes; bracts and bracteoles minute, less than 2 mm long, densely stellate-furfuraceous, caducous; pedicel densely stellate-furfuraceous, 2-3 mm long in central flowers, 1-2 mm long in lateral flowers. Hypanthium urceolate, 3-4 × 1-1.5 mm, densely stellate-furfuraceous; calyx lobes truncate with 4 triangular tips or occasionally slightly free triangular lobes, ca. 1 mm long; petal bud conical, 3-5 mm long, glabrous; mature petals oblong, 5-6 × ca. 2 mm, glabrous, red, base clawed, apex acute. Stamens 4, equal, filaments straight; alternipetalous stamens with 4-5 mm long filaments, anthers oblong or lanceolate, thecae ± straight, 4-5 mm long, pedoconnective short or slightly undeveloped, ca. 0.5 mm long, basal crest triangular, up to 1 mm long, lateral appendages paired, filiform, of unequal length, ca. 2 mm long at one side, 1-1.5 mm long on the other side. Ovary ¾ of hypanthium in length, apex villous; style glabrous, 7-10 mm long, straight but slightly curved apically; stigma capitate; extra-ovarial chambers 4, alternipetalous, shallow, reaching to ca. ⅓ of ovary. Fruits ovoid-urceolate, 5-6 × 3-3.5 mm, glabrescent, calyx remnant persistent up to 2 mm long. Seeds ca. 0.5 mm long.

Distribution.

Borneo (Sabah).

Ecology and habitat.

Montane forest at 900-1670 m elevation.

Note.

Dissochaeta rubiginosa resembles D. angiensis in indumentum and number of stamens, but differs by having more distinct triangular calyx lobes. The erect persistent calyx on the fruits is also different from D. angiensis .

Stapf & Green (1914) mention the collections Wallich 4052 from Penang and Helfer 2286 from Myanmar and refer them to this species. However, both specimens have a shorter (<3 mm long) campanulate hypanthium rather than the urceolate and long hypanthium (3-4 mm long) of D. rubiginosa and both are identified as D. biligulata in this revision. The flower petals were recorded as red, a colour uncommon in the genus (Stapf & Green 1914).

Specimen examined.

MALAYSIA. Sabah: Ranau, Mount Kinabalu,Gurulau Spur, 1670 m, L.S. Gibbs 3977 (K); Ibid., Marai Parai spur, 22 Nov 1915, M.S. Clemens 10941 (PNH); Ibid., Dallas, 900 m, J. Clemens & M.S. Clemens 26058A (K, L); Ibid., Sosopodon, 1500 m, Adam Gintus SAN 56381 (K, L); Ibid., S. Kokawa & M. Hotta 5190 (L); Tambunan, Mt. Alab, S. Kokawa & M. Hotta 2089 (L).

Figures

Map 25. Distribution of D. rostrata (●), D. rubiginosa (▲) and D. sagittata (■).