Dissochaeta marumioides Cogn. in A.DC. & C.DC., Monogr. Phan. 7: 556. 1891. non. D. marumioides Furtado, 1963 (see under D. spectabilis).

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

35. Dissochaeta marumioides Cogn. in A.DC. & C.DC., Monogr. Phan. 7: 556. 1891. non. D. marumioides Furtado, 1963 (see under D. spectabilis). Map 20

Type.

Indonesia. West Sumatra: Mt. Singgalang, 1600 m elev., O. Beccari s.n. (holotype: FI [FI007931, image seen]!).

Description.

Branchlets terete, 3-5 mm in diameter, brown stellate-furfuraceous; nodes swollen, with annular interpetiolar ridge; internodes 3-5 cm long. Leaves: petioles flattened, 10-15 mm long, densely stellate-furfuraceous; blades ovate-elliptic, 8.3-14 × 3.5-5 cm, membranous, base cordate, margin entire, apex acuminate, tip 1-2 cm long; nervation with 1 pair of lateral nerves and 1 pair of intramarginal nerves; adaxially glabrous, dark green, abaxially brown stellate-furfuraceous. Inflorescences terminal, up to 20 cm long, up to 20 flowers; main axis quadrangular, densely stellate-furfuraceous; primary axes up to 17 cm long with 5 nodes, secondary axes up to 3 cm long with 1 or 2 nodes, tertiary axes when developed 0.6-0.7 cm long with 1 node; bracts leaf-like, oblong-lanceolate, 15-22 × 4-6 mm, densely brown stellate-furfuraceous; bracteoles linear, 2-3 mm long, densely brown stellate-furfuraceous; pedicels densely brown stellate-furfuraceous, ca. 3 mm long in central flowers, 1-2 mm long in lateral flowers. Hypanthium campanulate, 7-9 × 3-5 mm, densely with stellate-furfuraceous and scattered, thickened, 1-2 mm long bristles; calyx lobes rounded, ca. 2 mm long, margin ciliate, apex obtuse, stellate-furfuraceous; petal buds conical, 3-5 mm long, acute; mature petals elliptic to suborbicular, ca. 12 × 9 mm, base clawed, apex acute, glabrous. Stamens 8, unequal, filaments curved sideways, glabrous; alternipetalous stamens with 6-7 mm long filaments, anthers slightly curved, lanceolate, thecae ca. 8 mm long, pedoconnective ca. 2 mm long, basal crest triangular, ca. 1.5 mm long, thin, entire or bifid, lateral appendages 4, filiform, 2-3 mm long; oppositipetalous stamens with ca. 6 mm long filaments, anthers sinuate, curved, thecae ca. 8 mm long, basal crest minute, ca. 0.3 mm long, lateral appendages paired, filiform appendages 2-3 mm long. Ovary ⅔ of hypanthium in length, apex villous; style ca. 15 mm long, curved at top, glabrous; stigma minute; extra-ovarial chambers 8, extending nearly to the base of the ovary. Fruits not seen.

Distribution.

Sumatra (West).

Ecology and habitat.

Montane forest at ca. 1600 m elevation.

Note.

Dissochaeta marumioides is only known from the type from Mount Singgalang, West Sumatra. This species has a non-bristly indumentum on branchlets and leaves; though sparse bristles are present on the hypanthium and calyx lobes. The 4 lateral appendages of the alternipetalous stamens are exceptional, all other species in the genus having 2. The calyx lobes with rounded apex are similar to those of D. rostrata from Borneo, but the species differs in the shape of the bracts.

Figures

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