Lasianthus brevipedunculatus H.Zhu, 2012

Zhu, H., Roos, M. C. & Ridsdale, C. E., 2012, A taxonomic revision of the Malesian species of Lasianthus (Rubiaceae), Blumea 57 (1), pp. 1-102 : 21

15. Lasianthus brevipedunculatus H.Zhu , sp. nov. — Fig. 6

Proximus L. nervosus King & Gamble ,sed foliis majoribus 4.5–8 cm longis 2–3 cm latis, cymis brevipedunculatis, floribus 5-meris, lobis calycis triangulatooblongis et pyrenis 5 differt. —

Typus: Nagamasu 3359 ( holo L), W Sumatra, Gunung Sago , 2100–2260 m alt., in upper montane forest around the summit, 30 Oct. 1988 .

Shrub, c. 2 m high; branchlets terete, c. 1.5 mm diam, densely brown-yellowish tomentose. Leaves elliptic-oblong to ovate-oblong, 4.5–8 by 2–3 cm, coriaceous, glabrous above, puberulous beneath, densely tomentose hairs on midrib and nerves beneath, apex acute or cuspidate, base subrounded, midrib depressed above, prominent beneath, nerves flat or slightly depressed above, prominent beneath, 5 –6 pairs, ascending at an angle of 50–60°, curved to margin, nervules prominent on both surfaces, parallel, margin hirsute; petioles 4–6 mm long, densely tomentose. Stipules triangular, 2 mm long, densely tomentose. Inflorescences shortly peduncled; peduncles 1– 3 mm long, densely tomentose; bracts 1–2, linear, c. 2 mm long, tomentose. Flowers sessile; calyx hirsute external surface, lobes 5, oblong or lanceolate-oblong, 3 mm long, tube very short, less than 1 mm long; corolla 4–5 mm long, tomentose external surface, lobes 5, triangular-oblong, 2 – 3 mm long; stamens 5; ovary with 5 locules. Drupes c. 4 mm diam, sub-globose, subglabrous, crowned by 5 calyx lobes; pyrenes 5.

Distribution — Indonesia (W Sumatra).

Habitat & Ecology — In upper montane forest at 2100 m altitude.

Note — This species is closely related to L. nervosus from Malaysian mountains. It differs from the latter by having relatively large leaves (4.5–8 by 2–3 cm), cymes shortly peduncled, flowers 5-merous, calyx lobes triangular-oblong, and drupes with 5 pyrenes. Lasianthus nervosus has leaves of 2.5 – 3.5 by 1.5 cm, cymes sessile, flowers 4-merous, calyx with triangular teeth, and drupes with 4 pyrenes.

Figures

Fig. 6 Lasianthus brevipedunculatus H.Zhu. a. Habit; b. detail of lower surface of leaf showing indumentum and parallel nervules; c. detail of node showing stipule and axillary inflorescences; d. corolla split opened; e. calyx split opened; f. fruit (all: H. Nagamasu 3359, holo L).