Lasianthus lancilobus 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 : 51

65. Lasianthus lancilobus H.Zhu , sp. nov. — Fig. 19

Proximus L. robinsonii Ridl. , sed ramulis costis nervis subtus, pedunculis et calycibus sparsim hirsutis, nervis 5–6-binatis, nervulis subparallelis, petiolis 6–8 mm longis, bracteis late-linearis costatis 1.5 mm longis et lobis calycis lanceolatis nervatis differt. —

Typus: Church et al. 2639 ( holo L; iso K), Borneo, W Kalimantan, Serawai , 1600 m alt., in upper montane mossy forest, 22 Oct. 1995 .

Treelet, 2 m high; branchlets terete, c. 1.5 mm diam, deeply brown, sparsely hirsute. Leaves: blades oblong, 6 –13 by 2.5 – 3.5 cm, chartaceous, glabrous except sparsely hirsute midrib and nerves beneath, apex acuminate to shortly caudate, base acute, midrib slightly depressed above, prominent beneath, nerves flat above, prominent beneath, 5– 6 pairs, nervules obscure above, conspicuous beneath, subparallel; petioles 6– 8 mm long, hirsute. Stipules lanceolate, c. 3 mm long, hirsute. Inflorescences peduncled; peduncles slender, c. 0.3 mm diam, 2.5– 3 cm long, hirsute; bracts 2 at each node, usually unequal, longer ones linear and with a midrib, up to 1.5 cm long, 1 mm broad, sparsely hirsute; shorter ones narrowly linear, hirsute. Flowers pediceled; pedicels 1–3 mm long, hirsute; calyx hirsute, lobes 4, lanceolate, usually nerved, 5 mm long, hirsute external surface, tube c. 2 mm long; corolla not seen. Drupes subglobose, glabrous, 4 obtuse ridges, verrucose on surface, 4–5 mm diam, crowned by lanceolate calyx lobes.

Distribution — Indonesia (W Kalimantan).

Habitat & Ecology — In upper montane mossy forest. Flowering in October.

Note — This species is characterized by its slender peduncles, linear bracts with a midrib and nerved lanceolate calyx lobes. It is closely related to L. robinsonii , but differs from the latter by having sparsely hirsute branches and leaf midrib and nerves beneath, peduncles and calyx; nerves 5 – 6 pairs, nervules subparallel; petioles 6 – 8 mm long; bracts broadly linear with a midrib, up to 1.5 cm long; calyx lobes lanceolate, nerved. Lasianthus robinsonii has spreading tomentose branches, leaf nerves beneath and peduncles; nerves 8 pairs, nervules reticulate; petioles short, less than 3 mm long; bracts subulate-linear, less than 1 cm long and without a midrib; calyx lobes subulate.

Figures

Fig. 19 Lasianthus lancilobus H.Zhu. a. Habit with inflorescences; b. detail of branch; c. detail of inflorescence; d. calyx (all: A.C. Church et al. 2639, holo L).