Lasianthus depressineurus 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 : 35

38. Lasianthus depressineurus H.Zhu , sp. nov. — Fig. 11

Proximus L. inodorus Blume , sed foliis minoribus ovato-lanceolatis, costis et nervis supra conspicue depressis, lobis calycis ovatis longioribus tubo differt. —

Typus: Dyg Awa & Lee S.50579 ( holo L; iso K, MO), Borneo, Sarawak, Bt. Lawi, Bario , 1290 m alt., in hill mixed dipterocarp forest, on top of the ridge, 3 Aug. 1985 .

Treelet, 2 m high; branchlets slender, terete, c. 1 mm diam, densely tomentose. Leaves: blades ovate-lanceolate, 8–11 by 1.5 cm, coriaceous, glabrous except pubescent midrib and nerves beneath, apex caudate, base acute or subrounded; midrib and nerves deeply depressed above, strongly prominent beneath, nerves 6–7 pairs, ascending at an angle of 45–60°, curved to margin, nervules obscure above, prominent beneath, reticulate, glabrous, margin conspicuously recurved; petioles 5 – 8 mm long, densely tomentose. Stipules triangular, c. 2 mm long, densely tomentose. Inflorescences sessile; bracts ovate-orbicular, c. 3 mm long, pubescent surfaces; bracteoles oblong, c. 2.5 mm long, pubescent. Flowers fascicular, sessile; calyx campanulate, pubescent, lobes 5, ovate, c. 2.5 mm long, 1.5 mm broad, pubescent both surfaces, densely hirsute on margin, tubes c. 2 mm long; corolla not seen. Drupes globose, c. 3 mm diam, pubescent, crowned by persistent ovate, c. 4 mm long calyx lobes; pyrenes 4, smooth on the abaxial face.

Distribution — Malaysian ( Sarawak).

Habitat & Ecology — In montane forest between 1290 – 1400 m altitude. Flowering and fruiting in August.

Additional specimen examined. Borneo, Sarawak, Limbang, D. Awa & B. Lee S.47839 (L).

Note — This species is characterized by its deeply depressed midrib and nerves above surface and ovate-orbicular bracts. It seems to be related to L. inodorus , but conspicuously differs from the latter by having small ovate-lanceolate leaves with deeply depressed midrib and nerves above, ovate calyx lobes longer than the tube.

Figures

Fig. 11 Lasianthus depressineurus H.Zhu. a. Habit with inflorescences; b. detail of lower surface of leaf; c. detail of upper surface of leaf showing reticulate nervules; d. detail of node showing stipule and axillary inflorescence; e. bract; f. bracteole; g. stipule; h. calyx split opened; i. immature fruit (all: Dyg Awa & B. Lee S.50579, holo L).