Dissochaeta horrida (Bakh.f.) 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

26. Dissochaeta horrida (Bakh.f.) Karton. comb. nov. Fig. 18 , Map 17

Dissochaeta rostrata Korth. var. horrida (Bakh. f.) J.F.Maxwell, Gard. Bull. Sing. 33: 320. 1980.

Basionym.

Macrolenes horrida Bakh. f., Contr. Melastom.: 208. 1943.

Type.

Indonesia. West Sumatra: Agam, Brani, 850 m elev., 22 Jun 1918, H.A.B. Bünnemeijer 3200 (holotype: L [L0537276]!; isotypes: BO [BO1751324, BO1751325]!).

Description.

Climbing up to 2 m in height. Branchlets terete, 4-5 mm in diameter, densely covered with brown-reddish pubescent hairs and with 4-5 mm long brown-reddish bristle hairs, young parts densely covered with red pubescent hairs and bristle hairs; nodes swollen, with interpetiolar ridge; internodes 7-8 cm long. Leaves: petioles terete, 10-15 mm long, densely covered with brown-reddish pubescent hairs and with 4-5 mm long brown-reddish bristle hairs; blades broadly ovate to suborbicular, 13-18 × 6-10 cm, subcoriaceous, base emarginate, margin entire, apex acuminate, tip 0.5-1 cm long; nervation with 2 pairs of lateral nerves and 1 pair of intramarginal nerves; adaxially glabrous, dark green, abaxially densely brown-reddish pubescent. Inflorescences terminal, up to 60 cm long, many-flowered; main axis angular, densely covered with brown-reddish pubescent hairs and with 4-5 mm long brown bristle hairs; primary axes up to 34 cm long with 6 or 7 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, 7-9 mm long, densely covered with brown-reddish pubescent hairs and with 4-5 mm long brown-reddish bristle hairs; bracteoles subulate, ca. 2 mm long, densely covered with brown-reddish pubescent hairs and with 4-5 mm long brown-reddish bristle hairs; pedicels densely covered with brown pubescent hairs and with glandular tip bristle hairs, 6-7 mm long in central flowers, 2-3 mm long in lateral flowers. Hypanthium tubular, 7-8 × ca. 3 mm, densely covered with brown-reddish pubescent hairs and with brown-reddish glandular-tipped bristle hairs; calyx lobes linear-lanceolate, 6-10 mm long, base truncate, apex acute, densely covered with brown-reddish pubescent hairs and with glandular-tipped bristle hairs; petal bud conical, 3-4 mm long, glabrous; mature petals oblong to suborbicular, 6-8 × 5-6 mm, purple. Stamens 8, subequal, filaments curved sideways; alternipetalous stamens with 6-8 mm long filaments, anthers slender, curved, sickle-shaped, thecae 12-13 mm long, pedoconnective with 1-3 mm long, basal crest minute, triangular, ca. 0.5 mm long, lateral appendages paired, filiform, 1.5-2 mm long; oppositipetalous stamens with 5 mm long filaments, bent at the end, anthers curved, S-shaped, thecae 9-10 mm long, basal crest consisting of minute auricles, ca. 0.3 mm long, lateral appendages paired, auricles, 0.5-1 mm long. Ovary ¾ of hypanthium in length, apex villous; style 15-20 mm long, glabrous; stigma minute; extra-ovarial chambers 8, extending to the base of the ovary. Fruits urceolate, ca. 10 × 5-6 mm, densely covered with brown-reddish pubescent hairs and with glandular-tipped bristle hairs; calyx lobe remnants persistent, lanceolate, 6-8 mm long, reflexed. Seeds ca. 0.7 mm long.

Distribution.

Sumatra (West).

Ecology and habitat.

Lowland dipterocarp forest or open cliff area at 500-850 m elevation.

Note.

Dissochaeta horrida is easy to recognise because most parts have reddish brown pubescent hairs and dense bristle hairs except the green, glabrous adaxially surface of the leaf blades. The shape of the calyx lobes (linear-lanceolate, 6-10 mm long) resembles D. floccosa , also from Sumatra, but the indumentum of the latter is floccose rather than pubescent.

Specimens examined.

INDONESIA. Riau: Indragiri, Taluk, 11 Jan 1956, W. Meijer 4271 (L). West Sumatra: Agam, Brani, 850 m, 22 Jun 1918, H.A.B. Bünnemeijer 3200 (BO, L); Lima Puluh Kota, Harau Valley, Sarasah Bonta, 500 m, 2 May 2001, Uce et al. 106 (ANDA); Ibid., 11 Sep 2017, A. Kartonegoro 1073 (BO, L).

Figures

Map 17. Distribution of D. hirsutoidea (●), D. horrida (■) and D. intermedia (▲).

Figure 18. Dissochaeta horrida a habit b branchlet c hypanthium d fruits. Photographs by A. Kartonegoro; vouchers: Kartonegoro 1073 (BO, L).