Dissochaeta rectandra 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

45. Dissochaeta rectandra Karton. sp. nov. Fig. 25 , Map 24

Type.

Malaysia. Pahang: Fraser’s Hill, 3 Aug 1967, J.C. Carrick 1606 (holotype L [L.2533494]!; isotypes: K!, KLU n.v., L [L.2533495]!, SING n.v.).

Diagnosis.

Resembles D. bakhuizenii Veldkamp. Leaf blade margin entire or thinly serrate with glabrous to sparsely stellate punctation below. Hypanthium campanulate-angular, 6-8 × 3-3.5 mm, glabrescent to sparsely stellate-puberulous, calyx lobes truncate with 4 small undulate points, 1-1.5 mm long, glabrous outside, stellate-furfuraceous inside. Stamens 8, subequal, filaments and anthers straight upwards, alternipetalous stamens with triangular basal crest and paired, filiform, lateral appendages, oppositipetalous stamens with ligular basal crest and paired filiform appendages. Fruits with mammiform apex.

Description.

Climbing up to 7.5 m. Branchlets terete, 3-5 mm in diameter, glabrescent; nodes swollen, interpetiolar ridge distinct with annular crest-like ridge; internodes 5-12 cm long. Leaves: petioles flattened, 10-23 mm long, stellate-punctate; blades elliptic or ovate-elliptic, 9.5-18 × 5-9.2 cm, membranous, base rounded to slightly cuneate, margin entire or thinly serrate, apex acuminate, tip 1-2 cm long; nervation with 1-2 pairs of lateral nerves and 1 pair of intramarginal nerves; adaxially glabrous, dark green, abaxially glabrous to brownish stellate-punctate, maroonish and glabrous when young. Inflorescences terminal, up to 40 cm long, many-flowered; main axis terete, glabrescent to sparsely stellate-puberulous; primary axes up to 33 cm long with 5 or 6 nodes, secondary axes up to 10 cm long with 3 or 4 nodes, tertiary axes 1-2.5 cm long with 1 or 2 nodes, quarternary axes when developed up to 0.8 cm long with 1 node; bracts linear, 2-2.5 mm long, stellate-furfuraceous, caducous; bracteoles subulate, 1-1.5 mm long, stellate-furfuraceous; pedicels stellate-furfuraceous, 4-6 mm long in central flowers, 2-3 mm long in lateral flowers. Hypanthium campanulate-angular, 6-8 × 3-3.5 mm, glabrescent to sparsely stellate-puberulous; calyx lobes truncate with 4 small undulate points, 1-1.5 mm long, glabrous outside, stellate-furfuraceous inside; petal buds conical, 4-9 × 2-3 mm, glabrous; mature petals obovate to suborbicular, 10-11 × 8-9 mm, base clawed, margin ciliate, apex rounded, glabrous, pink to dark purple. Stamens 8, subequal, filaments straight, white pinkish; alternipetalous stamens with 8-9 mm long filaments, anthers lanceolate, thecae 7-8 mm long, straight, yellow, pedoconnective 1.5-2 mm long, basal crests triangular, 1-1.5 mm long, acute, lateral appendages prolonged from basal crest, paired, filiform, 2-2.5 mm long; oppositipetalous stamens with filaments 7-8 mm long, bent at top, anthers oblong-lanceolate, thecae 6-7 mm long, straight, yellow, basal crest ligular, 1-1.5 mm long, apex narrow, lateral appendages paired, filiform, 2-3 mm long. Ovary half as long as hypanthium, apex pubescent, bristly; style 12-13 mm long, straight, curved at top, glabrous; stigma minute, capitate; extra-ovarial chambers 8, extending from the middle to the base of the ovary. Fruits urceolate, 8-10 × 6-9 mm, apex mammiform, bristly, rest glabrous; calyx lobes persistent, erect. Seeds ca. 0.5 mm long.

Distribution.

Peninsular Malaysia (Selangor and Pahang).

Ecology and habitat.

Montane forest, open areas along road sides at 1280-1800 m elevation.

Etymology.

The species is named after the orientation and shape of its stamens, erect, straight upwards when mature.

Note.

Dissochaeta rectandra resembles D. bakhuizenii in having 8 fertile stamens, a triangular basal crest (alternipetalous) and ligular basal crest (oppositipetalous). Dissochaeta rectandra has thinly serrate leaf margins, large flowers and longer lateral appendages on the stamens (vs. entire margins of leaf blades, smaller flowers and short to absent lateral appendages in D. bakhuizenii ). This species is restricted to the montane forest of Fraser’s Hill (Pahang) and the Genting Highlands (Selangor).

Specimens examined.

MALAYSIA. Pahang: Fraser’s Hill, 3 Aug 1967, J.C. Carrick 1606 (K, L); Ibid., Richmond, 1280 m, 16 Apr 1955, J.W. Purseglove 4112 (L). Selangor: Genting Highlands, Gunong Ulu Kali, 1800 m, 3 Jun 1978, J.F. Maxwell 78-307 (L); Ibid., 1500 m, 3 Jun 1978, J.F. Maxwell 78-312 (L).

Figures

Map 24. Distribution of D. pubescens (●), D. rectandra (■) and D. vacillans (▲).

Figure 25. Dissochaeta rectandra a habit b inflorescence c hypanthium d open flower e ovary f alternipetalous stamens g oppositipetalous stamens h fruit. [drawn from Carrick 1606 (L).