Dissochaeta latifolia (Triana) 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

31. Dissochaeta latifolia (Triana) Karton. comb. nov. Map 19

Diplectria latifolia (Triana) Kuntze, Revis. Gen. Plant 1: 246. 1891.

Basionym.

Anplectrum latifolium Triana, Trans. Linn. Soc. London 28: 85. 1872.

Type.

Malaysia. Borneo, 1853, T. Lobb s.n. (lectotype, designated by Veldkamp et al. 1979, pg. 412: K [K000859553]!).

Description.

Climbing up to 9 m in height. Branchlets terete, 5-6 mm in diameter, glabrous to covered with brown stellate-furfuraceous hairs; nodes swollen, with pectinate or subulate interpetiolar appendages, apex acute, up to 10 mm long and 1 mm wide, pointing upwards and downwards; internodes 10-16 cm long. Leaves: petioles terete, 15-25 mm long, densely covered with brown stellate-furfuraceous hairs; blades suborbicular to ovate, 17-19 × 8.5-10 cm, subcoriaceous, base slightly subcordate, margin entire, apex acute; nervation with 1 or 2 pairs of lateral nerves and 1 pair of intramarginal nerves; adaxially glabrous, glossy green, abaxially sparsely brown stellate-furfuraceous to glabrescent. Inflorescences terminal, up to 20 cm long, many-flowered; main axis angular, densely stellate-furfuraceous; primary axes up to 18 cm long with 4 or 5 nodes, secondary axes up to 4 cm long with 2 or 3 nodes, tertiary axes up to 0.8 cm long with 1 or 2 nodes; bracts linear, 4-6 mm long, densely stellate-furfuraceous; bracteoles subulate, 1-3 mm long, densely stellate-furfuraceous; pedicels densely stellate-furfuraceous, often with a few scattered capitate bristles, 5-6 mm long in central flowers, 2-3 mm long in lateral flowers. Hypanthium tubular, ca. 6 × 2 mm, glabrous to glabrescent; calyx lobes truncate, level, ca. 0.5 mm long; petal bud conical, 3-4 mm long, apex acuminate and bristly; mature petals suborbicular, 6-7 × ca. 6 mm, base clawed, apex acuminate, pink. Stamens 8, unequal, filaments straight; alternipetalous stamens staminodial with 2-3 mm long filaments, anthers rudimentary, terete, thecae 2-3 mm long, basal crest triangular or ovate, 1-2 mm long, apex acuminate, lateral appendages paired, ligular, ca. 2 mm long; oppositipetalous stamens with 4-5 mm long filaments, anthers thick, curved, hook- or S-shaped, thecae 10-11 mm long, apex rostrate, yellow, basal crest ligular, ca. 1 mm long, lateral appendages absent or minute, bifid, ca. 0.5 mm long. Ovary ⅔ of hypanthium in length, apex glabrous; style curved at the end, 8-10 mm long, glabrous, slender; stigma minute; extra-ovarial chambers 4, oppositipetalous, extending to the base of the ovary. Fruits urceolate, 8-9 × ca. 6 mm, glabrous; calyx lobe remnants persistent, erect. Seeds ca. 0.75 mm long.

Distribution.

Borneo.

Ecology and habitat.

Lowland mixed dipterocarp forest or heath forest at 45-150 m elevation.

Note.

Dissochaeta latifolia resembles D. pubescens in the tomentose indumentum of the branchlets, abaxially leaf surfaces and inflorescences. The size and shape of the leaves of both species are also similar, sometimes resulting in a misidentification. Dissochaeta latifolia is different in not having a membranous calyptra that encloses the petal bud before anthesis. The pectinate and subulate appendages in the interpetiolar nodal ring are also distinct in D. latifolia , making it easy to recognise amongst all species of Dissochaeta .

Specimens examined.

MALAYSIA. Sarawak: O. Beccari PB 800 (K, P); O. Beccari PB 1089 (K); T. Lobb s.n. (K); Miri, Lambir Hills, 152 m, 10 Jun 1961, D. Bakar S.4367 (K, L); Ibid., 5 Dec 1962, Joseph Au S.17256 (L); Kuching, Semariang Batu, 25 Jun 1976, Bagong et al. S.37642 (K, L); Lundu, Sematan, Pueh, Sungai Kopak, 200 m, 20 Aug 1996, R. Jawa & S.H. Lai S.74524 (L). BRUNEI. Belait: Sungai Liang, 1 Feb 1989, N. Nangkat 89 (K, L); Andulau, 45 m, 24 Apr 1957, P.S. Ashton S.5922 (K, L). INDONESIA. Central Kalimantan: Barito Ulu, 24 Jun 1990, C.E. Ridsdale PBU 647 (BO, K, L).

Figures

Map 19. Distribution of D. johorensis (●), D. latifolia (■) and D. leprosa (▲).