Lasianthus sabahensis 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 : 81

109. Lasianthus sabahensis H.Zhu , sp. nov. — Fig. 34

Similis L. sterophyllo Merr. , sed limbis calycis 4 minute dentibus, ovariis 3-locularibus, pyrenis 2 raro 3 differt. — Typus: Chew & Corner RSNB 4598 (holo L; iso K), Malaysia (Sabah), Mt Kinabalu, 5000 ft, Bembangan River , 1.3.1964 .

Shrubs, up to 3 m high; branchlets terete, c. 2 mm diam, puberulous to subglabrous, more or less compressed in the youngest part. Leaves: blades oblong or lanceolate-oblong, 9 –15 by 2 –5 cm, coriaceous, glabrous above, puberulous hairs on midrib and nerves beneath, apex acute to acuminate or cuspidate, margin reflexed, base cuneate, midrib prominent on both surfaces, nerves depressed or flat above, prominent beneath, 7– 8 pairs, ascending at an angle of 60–80°, curved to the margin, nervules loosely anastomosing, subparallel, slightly prominent on both surfaces; petioles 1–1.5 cm long, puberulous. Stipules triangular, 4–6 mm long, with an acuminate to cuspidate apex, puberulous. Cymes sessile or shortly tuberculate; bracts absent. Flowers sessile, fascicular; calyx campanulate, tube c. 1 mm long, limb c. 1–1.5 mm long, more or less expanded, with 4 minute teeth, puberulous on both sides; corolla tubular, c. 5 mm long, puberulous outside, densely hairy in the upper half of the tube and the lobes inside, lobes 4; ovary 3-locular. Drupes ellipsoid, 8 – 9 mm long, c. 5 mm diam, puberulous or glabrous, crowned by a cupular calyx limb with 4 minute teeth, pyrenes 2, rarely 3, with thick, hard wall, smooth on the abaxial face, between pyrenes cork-like structure.

Distribution — Endemic to Borneo.

Habitat & Ecology — In forest between 800–1800 m altitude. Flowering from September to January.

Notes — This species is similar to L. sterrophyllus , but differs in having relatively large stipules (4–6 mm long), calyx limbs with minute teeth, 3-locular ovary and 2-, rarely 3-pyrened drupes with cork-like structure between pyrenes, while L. sterrophyllus has stipules which are 3–4 mm long, calyx with 4 triangular lobes which are 2 mm long, and drupes with 5 pyrenes.

This species seems somewhat between Lasianthus and Saldinia morphologically. Saldinia has a 2-locular ovary which develops to a 1-pyrened drupe with a hard wall. Lasianthus has an ovary with 3 or more locules, which develops to a drupe with 1 or more pyrenes with a hard and thick wall. Lasianthus sabahensis has a 3-locular ovary which develops to a drupe with 2 rarely 3 pyrenes of hard and thick walls.

Figures

Fig. 34 Lasianthus sabahensis H.Zhu. a. Habit with fruit; b. detail of node showing stipule and axillary inflorescences;c. calyx; d. corolla split opened; e. cross section of ovary; f. fruit; g. cross section of fruit (all: Chew & Corner RSNB 4598, holo L).