Dissochaeta floccosa (J.F.Maxwell) 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

19. Dissochaeta floccosa (J.F.Maxwell) Karton. comb. nov. Map 13

Basionym.

Dissochaeta rostrata Korth. var. floccosa J.F.Maxwell, Gard. Bull. Singapore 33: 319, fig. 5. 1980.

Type.

Indonesia. West Sumatra: Pajakumbuh, Pakan Raba, Aer nan Dingin, 600 m elev., 1 Sep 1957, S. Maradjo 350 (holotype: L [L0537273]!; isotypes: L [L0537271]!, PNH [PNH59964, image seen]!, SING n.v.).

Description.

Branchlets terete, 5-6 mm in diameter, floccose, covered with dense stellate pubescent hairs and with 1-2 mm long capitate bristle hairs; nodes swollen, with interpetiolar ridge; internodes 12-14 cm long. Leaves: petioles terete, ca. 10 mm long, floccose, densely covered with pubescent hairs and with 1-2 mm long brown bristle hairs; blades ovate or ovate-elliptic, 17-20 × 7-9.5 cm, subcoriaceous, base emarginate to slightly cordate, margin entire, apex acuminate, tip 2-3 cm long; nervation with 2 pairs of lateral nerves and 1 pair of intramarginal nerves; adaxially glabrous, abaxially densely floccose, covered with pubescent hairs. Inflorescences terminal, up to 40 cm long, many-flowered; main axis angular, floccose, densely covered with pubescent hairs and 1-2 mm long capitate bristle hairs; primary axes up to 36 cm long with 5 or 6 nodes, secondary axes up to 6 cm long with 2 or 3 nodes, tertiary axes up to 2 cm long with 1 or 2 nodes, quarternary axes when developed up to 1 cm long with 1 node; bracts linear, 10-13 mm long, floccose, densely covered with pubescent hairs and with 1-2 mm long capitate bristle hairs; bracteoles subulate, 5-10 mm long, floccose, densely covered with pubescent hairs and with 1-2 mm long capitate bristle hairs; pedicels floccose, densely covered with pubescent hairs and with capitate bristle hairs, 6-7 mm long in central flowers, 2-3 mm long in lateral flowers. Hypanthium tubular, 7-9 × 3-4 mm, floccose, densely covered with pubescent hairs and with capitate bristle hairs; calyx lobes linear-lanceolate or triangular, 7-11 mm long, floccose, densely covered with pubescent hairs and capitate bristle hairs, base truncate, apex acute; petal bud conical, 3-5 mm long; mature petals not seen. Stamens 8, subequal, filaments curved sideways; alternipetalous stamens with 8-9 mm long filaments, anthers slender, curved, sickle-shaped, thecae 14-15 mm long, pedoconnective 2-3 mm long, basal crest minute, triangular, ca. 1 mm long, lateral appendages paired, filiform, 2-4 mm long; oppositipetalous stamens with ca. 8 mm long filaments, anthers S-shaped, thecae 12-14 mm long, basal crest with minute auricles, ca. 0.5 mm long, lateral appendages paired auricles, 1-1.5 mm long. Ovary ¾ of hypanthium in length, apex floccose; style glabrous, in bud ca. 15 mm long; stigma minute; extra-ovarial chambers 8, extending to the base of the ovary. Fruits urceolate, ca. 10 × 5-6 mm, floccose, densely covered with pubescent hairs and capitate bristle hairs; calyx lobes remnant persistent, 8-11 mm long, reflexed. Seeds ca. 0.5 mm long.

Distribution.

Sumatra (West).

Ecology and habitat.

Lowland forest at 300-600 m elevation.

Note.

Dissochaeta floccosa is known only from 2 collections. This species closely resembles D. horrida in having long, linear-lanceolate calyx lobes of up to 11 mm long and similar number and shape of the stamens, but differs in having a floccose indumentum all over with shorter bristle hairs.

Specimen examined.

INDONESIA. West Sumatra: Payakumbuh, Pakan Raba, 600 m elev., 1 Sep 1957, S. Maradjo 350 (L, PNH); Sawahlunto Sijunjung, Kulampi, 300 m, 21 Apr 2000, Erlo 32 (ANDA).

Figures

Map 13. Distribution of D. floccosa (●) and D. glabra var. glabra (■).