Lasianthus atroneurus H.Zhu, 2012

5. Lasianthus atroneurus H.Zhu View in CoL , sp. nov. — Fig. 1 View Fig

Similis L. chinensis Benth. , sed foliis crasse coriaceis, lobis calycis 4, pyre- nis 4 differt. Similis to L. pergamaceus King & Gamble , sed cymis sessilis, foliis lanceolatis, lobis calycis ovatis differt. —

Typus: Van Balgooy & Van Setten 5396 (holo L), Borneo, W Kalimantan, Gunung Palung , 1000 m alt., in montane forest of summit ridge on granite, 12 June 1986 .

Treelet, 3 m high; branchlets robust, c. 3 mm diam, compressed, fistulous, subglabrous, dark brown in the youngest part. Leaves: blades lanceolate, 12–19 by 3.5–4.3 cm, thickly coriaceous, glabrous above, puberulous to glabrescent beneath, apex acute, the base cuneate midrib flat to slightly prominent above, strongly prominent beneath, dark brown and puberulous or glabrescent beneath, nerves slightly prominent above, strongly prominent beneath, 7–8 pairs, ascending at an angle of 70–80°, curved to margin, dark brown and puberulous or glabrescent beneath, nervules conspicuously prominent on both surfaces, reticulate, puberulous or glabrescent beneath, margin conspicuously recurved; petioles 5–10 mm long, puberulous and dark in colour. Stipules subulate, c. 2 mm long, puberulous. Inflorescences axillary, sessile; bracts inconspicuous. Flowers sessile; calyx tubular-cupular, c. 4 mm long, densely puberulous external surface, calyx lobes 4, ovate, c. 1 mm long, slightly folded; corolla not seen. Drupes ellipsoid, c. 5 mm diam, puberulous, with 8 ridges (alternately 4 obtuse and 4 acute), crowned by persistent shortly cupular calyx limbs with ovate lobes; pyrenes 4.

Distribution — Endemic to Borneo (Kalimantan).

Habitat & Ecology — In montane forests on ridge top on granite soil at c. 1000 m altitude. Fruiting between March and June.

Additional specimen examined. Kalimantan, Gunung Palung , 1°12'S , 110°8'E, 1000 m alt., T. G. Laman et al. TL801 ( K, L).

Note — This species has conspicuously reticulate nervules and a tubular calyx with slightly folded ovate lobes, which points to relationship with L. chinensis , but differs from the latter in having thickly coriaceous leaves, calyx with 4 lobes and drupes with 4 pyrenes. It is similar to L. pergamaceus , but differs in having sessile cymes, lanceolate leaves and ovate calyx lobes, while L. pergamaceus has shortly peduncled cymes, oblong-elliptic leaves and truncate calyx limbs.