Lasianthus minutiflorus 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 : 62

79. Lasianthus minutiflorus H.Zhu , sp. nov. — Fig. 25

Proximus L. phymatodeus H.Zhu , sed foliis conspicue majoribus 15–28 cm longis 3.5 –5 cm latis, nervis 7–10-binatis, calycibus densely hirsutis, drupis levigatis et pyrenis abaxialiter levigatis differt. — Typus: Buwalda 6546 (holo L), Sumatra, Derapit ( C Sumatra), in primary forest .

Treelet, 1.5 – 2 m high; branchlets terete, 1.5– 2 mm diam, glabrous, brown. Leaves: blades ovate-lanceolate to ovate elliptic, coriaceous, 15– 28 by 3.5– 5 cm, glabrous on both surfaces, apex caudate, mucronate, margin slightly recurved, base acute or cuneate; midrib slightly prominent above, strongly prominent beneath, nerves flat above, prominent beneath, 7–10 pairs, ascending at an angle of 60–70°, curved to margin; nervules parallel, prominent on both surfaces, conspicuous beneath; petioles c. 1 cm long, glabrous or sparsely puberulous, dark-brown. Stipules triangular, 1.5– 3 mm long, puberulous, bristles from the inside base of stipules existent, c. 0.5 mm long. Inflorescences extremely congested; bracts inconspicuous. Flowers sessile, extremely small; calyx c. 1 mm long, densely hirsute, lobes 4–5, triangular-subulate, 0.5 mm long, densely hirsute on external surface; corolla not seen. Drupes subglobose, 4–5 mm diam, subglabrous, smooth, with 4–5 obtuse ridges; pyrenes 4–5, smooth on the abaxial face, sulcate on sides, ovate in the transverse section.

Distribution — Malaysia (Peninsular), Indonesia (Sumatra).

Habitat & Ecology — In lowland and lower montane primary forest. Flowering and fruiting between February and April.

Additional specimens examined. N Sumatra, Langkat, Soedarsono 250 (K, L), Soedarsono 327 (K, L). Peninsular Malaysia, Pahang, KEP­FRI 6443 (L); Ulu Kelantan, KEP­FRI 5476 (L); Kelantan, M.R. Henderson 19732 (K).

Note — This species is characterized by its extremely small flowers fascicled in the extremely congested cymes. It seems close to L. phymatodeus , but differs from the latter by having leaves conspicuously big (15–28 by 3.5– 5 cm), with 7–10 pairs of nerves, calyx densely hirsute, drupes smooth on surface, pyrenes smooth on the abaxial face, sulcate on sides from cross section view. Lasianthus phymatodeus has leaves 8–12 by 2–3.5 cm, with 4–5 pairs of nerves, calyx sparsely puberulous or glabrous, drupes strongly warty; pyrenes irregularly sharp ridges on all sides from cross section view.

Figures

Fig. 25 Lasianthus minutiflorus H.Zhu. a. Habit; b. detail of node showing axillary inflorescences; c. stipule; d. calyx; e. fruit; f. cross section of pyrene (all: Buwalda 6546, holo L).