Lasianthus laxifloroideus 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 : 53

67. Lasianthus laxifloroideus H.Zhu , sp. nov. — Fig. 20

Proximus L. laxifloro Merr. sed ramulis costia nervis subtus stipulis pedunculis calycis appressi-pubescentibus, foliis angustioribus, petiolis 5 mm longis, stipulis minoribus triangularis 2 mm longis, cymis 1–2 cm longis differt. A L. dinghoui H.Zhu foliis oblongis vel ovato-oblongis 2.5–4.5 cm latis apice acuminatis vel cuspidatis, lobis calycis lanceolatis 1.5 mm longis differt. —

Typus: Ching S. 40794 ( holo L ; iso K, L), Borneo, Sabah, Kelingkang Range , 1650 ft, in mixed dipterocarp forest, 10 Oct. 1979 .

Shrub, up to 3 m high; branchlets terete, c. 1.5 mm diam, densely appressed-pubescent. Leaves: blades oblong or ovate-oblong, 10–16 by 2.5–4.5 cm, subcoriaceous, glabrous except appressed-pubescent midrib and nerves beneath, apex acuminate to cuspidate, base abruptly acute to subrounded, midrib and nerves slightly prominent above, conspicuously prominent beneath, nerves 3 – 6 pairs, nervules prominent on both surfaces, more conspicuous beneath, parallel; petioles c. 5 mm long, appressed-pubescent. Stipules triangular, c. 2 mm long, appressed-pubescent. Inflorescences peduncled, appressed-pubescent; peduncles 0.5 –2 cm long, trifurcate at each node; bracts subulate-linear, 2 – 3 mm long, pubescent; bracteoles small, subulate, c. 1 mm long. Flowers pediceled; pedicels 3 – 5 mm long, articulate, appressed-pubescent; calyx campanulate, appressed-puberulous, tube 1.5 mm long, lobes 4, oblong-lanceolate, c. 1.5 mm long; corolla glabrous external surface, 6–7 mm long, lobes 4. Drupes rhomboidal-globose, 5 mm diam, glabrous, verrucose external surface, conspicuously 4-ridged; pyrenes 4, strongly verrucose on abaxial face and sides.

Distribution — Malaysia (Borneo).

Habitat & Ecology — In lower montane forests between 350– 900 m altitude. Flowering in April; fruiting in October.

Additional specimens examined. W Kalimantan, Serawai, A.C. Church et al. 2001 (L); W Kalimantan, Kabupaten Sanggau, W. de Jong 889 (L); Sarawak, Lubok Antu, Dyg Awa et al. 44116 (L); Sabah, Kelingkang Range, Rena et al. S.58966 (L); Sabah, Serian , B. & K. Bremer 1650 (L); Sarawak, G. Lesong, B. Lee S.43203 (L).

Note — This species is closely related L. laxiflorus and L. dinghoui H.Zhu. It differs from L. laxiflorus by having appressed-pubescent branches, leaf midrib and nerves beneath, stipules, peduncles, and calyx; petioles 5 mm long; stipules small, triangular, c. 2 mm long; inflorescence 1–2 cm long. While L. laxiflorus is a glabrous plant and has petioles 6 –10 mm long, stipules lanceolate 5–7 mm long, inflorescence 3–4 cm long. It differs from L. dinghoui by having densely appressed-pubescent on branches, and leave beneath, leaves oblong to ovate-oblong, more than 2.5 cm broad; leaf apex acuminate to cuspidate; calyx lobes oblong-lanceolate, c. 1.5 mm long.

Figures

Fig. 20 Lasianthus laxifloroideus H.Zhu. a. Habit with inflorescences; b. detail of lower surface of leaf showing parallel nervules; c. detail of node showing stipule and axillary inflorescences; d. calyx; e. fruit; f. cross section of fruit (all: Y.P. Ching S.40794, holo and iso L).