Dissochaeta papuana (Mansf.) 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

40. Dissochaeta papuana (Mansf.) Karton. comb. nov. Map 21

Diplectria papuana (Mansf.) Bakh. f., Contr. Melastom.: 202. 1943.

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

Basionym.

Anplectrum papuanum Mansf., Nova Guinea 14: 202. 1924.

Type.

Indonesia. Papua: Siriworivier, Jul 1912, R.F. Janowsky 132 (lectotype, designated here: L [L0008872]!; isolectotype: BO [BO1865947]!).

Description.

Branchlets terete, 3-4 mm in diameter, glabrous; nodes swollen, with raised annular crest-like interpetiolar ridge, often with bristle hairs; internodes 6-8.7 cm long. Leaves: petioles terete, ca. 10 mm long, furfuraceous and dorsally with bristle hairs; blades ovate, 8-16 × 4.5-9 cm, membranous to subcoriaceous, base cordate, margin entire, apex acuminate, tip 1-1.5 cm long; nervation with 1 pair of lateral nerves and 1 pair of intramarginal nerves; surfaces glabrous, abaxially with a pair of glandular patches at the base. Inflorescences terminal, up to 30 cm long, many-flowered; main axis angular, covered with stellate hairs; primary axes up to 28 cm long with 6 or 7 nodes, secondary axes up to 13 cm long with 4 or 5 nodes, tertiary axes up to 5 cm long with 3 or 4 nodes, quarternary axes when developed 1-1.5 cm long with 1 or 2 nodes; bracts linear, ca. 3 mm long, stellate-furfuraceous, caducous; bracteoles subulate, ca. 1 mm long, densely stellate-furfuraceous; pedicels stellate-furfuraceous, ca. 3 mm long in central flowers, 1-2 mm long in lateral flowers. Hypanthium suburceolate, 3-4 × ca. 2 mm, glabrous; calyx lobes truncate, ca. 0.5 mm long, apex triangular; petal buds conical, 1.5-2 mm long, apex acuminate; mature petals ovate, 3-3.5 × ca. 2 mm, reflexed, base clawed, apex acute, glabrous. Stamens 8, unequal, filaments straight; alternipetalous stamens staminodial, with ca. 2 mm long filaments, anthers rudimentary, thecae ca. 2 mm long, slender, terete, basal crest triangular, ca. 1 mm long, thin, base emarginate or hastate, apex acute, lateral appendages absent; oppositipetalous stamens with ca. 3 mm long filaments, anthers thick, curved, S-shaped, thecae 3-3.5 mm long, yellow, basal crest bilobed, ca. 0.3 mm long, lateral appendages absent. Ovary half as long as hypanthium, apex glabrous; style 7-8 mm long, curved at the end, slender, glabrous; stigma minute, capitate; extra-ovarial chambers 4, oppositipetalous, extending to the middle of the ovary. Fruits subglobose, 3-4 × ca. 3 mm, glabrous; calyx lobe remnants persistent. Seeds ca. 0.5 mm long.

Distribution.

New Guinea (Indonesian Papua).

Ecology and habitat.

Lowland forest at river banks at ca. 50 m elevation.

Note.

Dissochaeta papuana resembles D. glabra in its glabrous appearance and pair of glandular patches at the abaxially base of the leaves, but differs in the ovate shape of the leaf blade and the more urceolate hypanthium.

Specimens examined.

INDONESIA. Papua: Geelvink Bay, Siriwo River, Jul 1912, R.F. Janowsky 132 (BO, L). West Papua: Sorong, 50 m, 28 Aug 1948, D.R. Pleyte 705 (BO, K, L).

Figures

Map 21. Distribution of D. micrantha (■), D. nodosa (●) and D. papuana (▲).