Schizostachyum langbianense V. T. Tran, N. H. Xia & H. N. Nguyen 2016, sp. nov.
Creators: name: Tien, Chinh Vu
name: Xia, Nianhe
name: Wong, Khoon Meng
name: Van, Duy Nong
name: Toan, Phan Nguyen Huu
name: Nguyen, Hoang Nghia
name: Tran, Van Tien
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Poales
Poaceae
Schizostachyum
Schizostachyum langbianense

description: Schizostachyum langbianense V.T. Tran, N.H. Xia & H.N. Nguyen, sp. nov. (Figs. 1, 2)
TYPE:— VIETNAM. Lam Dong Province: Lac Duong District, Lang Bian mountain, 12002’ 654 ’, 108026’ 278 ’’, alt. 1879 m, 11 October 2008, V.T. Tran & N.H. Nghia 460 (holotype: VAFS!; isotypes: DLU!, IBSC!, SING!).
It is similar to Schizostachyum ninhthuanense in having pseudospikelets with a few spikelets clustered on the short ultimate branchlets, but differs in having culm leaves where the apical portion of the sheath proper is horizontal or only slightly concave, culm leaf blades that are narrowly lanceolate, a palea apex which is not bifid and with the dorsal side furrowed between two keels.
Rhizome pachymorph. Culms erect, 4–8 m tall, 2–4 cm diameter; internodes terete, straight, 55–60 cm long, when young covered with sparse soft hairs; wall 0.2–0.3 cm thick; nodes swollen, with a ring of white powder c. 0.5 cm broad below each node. Branches numerous at each mid-culm node, slender, subequal. Culm leaves oblong, densely covered with hairs on the outer surface at its base, 23–24 x 7–8 cm; apical portion of sheath proper horizontal or only slightly concave; blade narrowly lanceolate, 8–14 x 0.7–0.8 cm, erect at first, then becoming reflexed; auricles low rims ca. 0.1 cm long, with 4–5 slender bristles ca. 0.4 cm long; ligule horizontal or subtruncate, short, 1–2 mm long, with fimbriae 2–4 mm long. Foliage leaves 4–5 per complement; sheaths often sparsely covered with white hairs; auricles inconspicuous, oral setae numerous, 2–4 mm long; ligule ca. 0.1 cm long; petiole ca. 0.3 cm long, ca. 0.15 cm thick; blades 20–22 x 2.5–3.5 cm, base rounded and oblique, adaxially and abaxially covered with sparse smooth hairs; margins minutely serrulate, 6–9 veins on each side of the midrib. Synflorescences ca. 1.3 cm long, pseudospikelets several clustered on the short ultimate branchlets, glabrous; prophylls ovate-lanceolate, 4–5 x 1.5–2 mm, thin, apex obtuse, two-keeled; bracts 1–3, oblong to oblong-lanceolate, upper 5–6 x 3–4 mm, papery, veins 11–13, apex obtuse to acute or mucronate; glumes absent; floret 1, fertile; rachilla internodes short, ca. 1–2 mm long; fertile lemma oblong–lanceolate, 9–10 x 4–4.5 mm, veins 11–13, apex acute, short-mucronate; palea ovate-lanceolate, 9–10 x 4–4.5 mm, involute, papery, dorsal surface of palea slightly furrowed between 2 keels, margins ciliate, apex acute (not bifid), short-mucronate, veins 11–13; lodicules 3, triangular or oblong, largest 2 x 1 mm, margins apically ciliate; stamens 6, ca. 5 mm long, connate at their base; anthers initially dull green, pale yellow when mature, ca. 2 mm long; style ca. 1.3 cm long; stigmas 3, purple, plumose. Fruit a nucoid caryopsis, ovoid-oblong, 5–6 x 2–3 mm, glabrous, with the persistent style base at its apex.
Etymology:— The species epithet refers to Lang Bian Mountain.
Morphological comparisons:— Schizostachyum langbianense has a few pseudospikelets in each cluster on the short ultimate inflorescence branchlets, and so resembles S. ninhthuanense (Tran et al. 2010) found in the same geographical area. However, in contrast, the culm leaves of S. langbianense have a slightly concave or horizontal apical portion, culm leaf blades that are narrowly lanceolate, an acute (not bifid) palea apex, and a dorsal palea surface that is furrowed between 2 keels. The characters states considered important for distinguishing these species are given in Table 1.
Geographic distribution and Habitat:— This new species is only known from the type collection and its distribution area is not too far from the type locality of Schizostachyum ninhthuanense (Fig. 3). Both of them occur on the Lang Bian Plateau, southern Vietnam, S. ninhthuanense being found in lower montane sites (400–1000 m a.s.l.), which is whereas the new species is found in higher elevations (1600–1900 m a.s.l.). S. ninhthuanense is found in open semi-deciduous and degraded forests, and S. langbianense is found in evergreen alpine forests or mixed broadleaved alpine forests, along valleys and mountain gorges. It is found in small populations, being apparently endemic to Lang Bian Mountain, Lac Duong District, Lam Dong Province, southern Vietnam.
Phenology:— Flowering and fruiting were observed in October 2008 and December 2009, respectively. New culm shoots often appear from May to August.
description: Published as part of Tien, Chinh Vu, Xia, Nianhe, Wong, Khoon Meng, Van, Duy Nong, Toan, Phan Nguyen Huu, Nguyen, Hoang Nghia & Tran, Van Tien, 2016, Schizostachyum langbianense, a new species of bamboo (Poaceae: Bambusoideae) from Lang Bian Mountain, Vietnam, pp. 181-186 in Phytotaxa 257 (2) on pages 182-185, DOI: 10.11646/phytotaxa.257.2.8, http://zenodo.org/record/13674598