Lasianthus nigrescens 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 : 66

84. Lasianthus nigrescens H.Zhu , sp. nov.

Proximus L. sabahensis H.Zhu , sed foliorum laminis oblongis apice cuspidatis basi subrotundatis, nervulis conspicue prominentibus,petiolis 5–7 mm longis et tubis calycis 3 mm longis differt. —

Typus: Beaman 8149 ( holo K), Malaysia ( Sabah), Ranau District, East Mesilau River , 1950–2100 m alt., in oak-laurel forest, 30 Dec. 1983 .

Shrubs, up to 2.5 m high; branchlets terete, c. 2 mm diam, glabrous, more or less compressed in the youngest part. Leaves: blades oblong, 6 –12 by 3– 5 cm, coriaceous, glabrous, turning black when dry, apex cuspidate, rarely acute, margin reflexed, base subrounded, rarely acute, midrib and nerves prominent on both surfaces, nerves 6–7 pairs, ascending at an angle of 80–90°, curved to the margin, nervules loosely anastomosing, subparallel, conspicuously prominent on both surfaces; petioles 5 –7 mm long, glabrous. Stipules triangular, c. 2 mm long, glabrous. Cymes sessile; bracts absent. Flowers sessile, fascicular; calyx campanulate, tube c. 3 mm long, with 4 c. 1 mm long minute teeth, puberulous or glabrous outside; corolla tubular, c. 1 cm long, puberulous or glabrous outside, lobes 4, c. 2 mm long, puberulous or glabrous. Drupes ellipsoid, 6 –7 mm long, c. 5 mm diam, glabrous, crowned by a cupular calyx limb with 4 minute teeth, 2-pyrene, with cork-like structure between pyrenes; pyrenes with a hard wall, smooth on the abaxial face.

Distribution — Endemic to Borneo.

Habitat & Ecology — In forest between 1800–2200 m altitude. Flowering and fruiting from March to December.

Note — Lasianthus nigrescens is close to L. sabahensis , especially in the same type of drupes that have a cork-like structure between pyrenes. Lasianthus nigrescens differs from the latter in having leaves oblong, with usually cuspidate apex and subrounded base, nervules conspicuously prominent on both surfaces; petioles 5–7 mm long; calyx tube 3 mm long, not expended at limb. Lasianthus nigrescens differs from L. membranaceus in having coriaceous leaves with nervules conspicuously prominent on both surfaces; drupes with cork-like structure between pyrenes; pyrene walls smooth on the abaxial face.