Lasianthus palawanensis 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 : 71

90. Lasianthus palawanensis H.Zhu , sp. nov. — Fig. 29

Proximus L. trichophlebus Hemsl. , sed foliis obovato-oblongis chartaceis, nervulis subreticulatis, lobis calycis 5 subulato-lanceolatis aequalis tubo differt. — Typus: Elmer 13252 (holo L), Philippines, Palawan Island , May 1911 .

Shrub; branchlets terete, robust,c. 2.5–3 mm diam, sparsely hirsute, densely at nodes, dark-brownish. Leaves: blades obovate-oblong, 10–12 by 3– 3.5 cm, chartaceous, glabrous and dark-brownish above, puberulous or glabrescent and lightly brownish beneath, apex cuspidate or shortly caudate, mucronate, base acute; midrib flat above, prominent and sparsely hirsute beneath, nerves slightly prominent above, prominent and hirsute beneath, c. 11 pairs, ascending at an angle of c. 60°, curved gradually to margin, nervules slightly prominent on both surfaces, obscure beneath, reticulate; petioles 3– 5 mm long, hirsute. Stipules triangular-lanceolate, 6 –7 mm long, hirsute. Inflorescences sessile, bracts fewer, linear, c. 2 mm long, hirsute. Flowers fascicular, sessile; calyx campanulate, c. 4 mm long, hirsute, lobes 5, subulate-lanceolate, c. 2 mm long; corolla c. 5 – 6 mm long, tube glabrous outside, lobes 5, lanceolate, c. 2 mm long, puberulous external surface; ovary with 5 locules. Drupes not seen.

Distribution — Endemic to Palawan Islands of Philippines.

Note — This species has hirsute hairs on nodes of branchlets, leaf nerves beneath, stipules, and calyx; stipules triangular-lanceolate, 6 –7 mm long. It seems closely related to L. trichophlebus , but differs from the latter by having obovate-oblong and chartaceous leaves with subreticulate nervules, calyx lobes 5, subulate-lanceolate,as long as calyx tube. Lasianthus trichophlebus has oblong and coriaceous leaves with parallel nervules, calyx lobes 4, triangular, shorter than calyx tube.

Figures

Fig. 29 Lasianthus palawanensis H.Zhu. a. Habit with inflorescences; b. detail of lower surface of leaf showing reticulate nervules; c. detail of node showing stipule and axillary inflorescences; d. calyx; e. calyx split opened; f. stipule (all: A.D.E. Elmer 13252, holo L).