Melocalamus guangxiensis D. Z. Li & J. X. Liu, 2025

Chen, Yu-Jin, Chen, Mei, Zhou, Meng-Yuan, Xu, Zu-Chang, Zhang, Yu-Xiao, Liu, Jing-Xia & Li, De-Zhu, 2025, Further investigation of Melocalamus (Poaceae, Bambusoideae) in China based on Skmer analysis and morphology, PhytoKeys 259, pp. 177-198 : 177-198

Melocalamus guangxiensis D. Z. Li & J. X. Liu sp. nov.

Fig. 7 Chinese name. “ 广西梨籐竹 ” (ɡuǎnɡ xī lí téng zhú ).

Type.

China • Guangxi: Chongzuo City, Ningming County, Chengzhong Town, Shanghe Village , 22°11'54.10"N, 106°58'41.96"E, alt. 163 m, 11 Apr 2023, Z. C. Xu et al. Xuzc 2023109 (holotype, KUN!, Barcode: 1643898; isotype, CSH!, Barcode: CSH 0219482 ) .

Diagnosis.

Melocalamus guangxiensis resembles M. puberulus , M. cordatus , M. pacoensis , M. truongsonensis and M. compactiflorus var. fimbriatus in the characters of foliage leaf auricles with radiate oral setae or culm leaf ligules with fringed long setae at the apex. However, M. guangxiensis can be easily distinguished by its unique culm sheaths, which feature a membranous projection on the basal outer margin, ca. 1–2 cm and culm leaf blades that are long- lanceolate, non-constricted at the base.

Description.

Perennial. Rhizomes pachymorph, short-necked. Culms slender, ca. 10–15 m long, 1–2 cm in diam.; internodes greyish-green, with densely white-brown pubescence, hollow, 50–80 cm long, wall 3–5 mm; nodes prominent, a ring of light-brown tomenta present above and below nodes; sheath scars prominent, corky, with residual base of culm leaf sheaths. Buds solitary, triangle, puberulent, the lateral edges ciliolate. Branches several, slender and equal length, dominant one equal to culm in size. Culm leaves tardily deciduous, ca. 2 / 5 to 1 / 2 as long as the internodes, 20–30 cm long, base 15–20 cm wide; sheaths leathery, long-triangle, apex concave or truncated, margins thin, membranous, with white powder and brown hairs abaxially, base of outer one with a subcircular projection, ca. 1–2 cm; auricles wavy, narrow rim, with several fimbriate long oral setae, easily dropped; ligules prominent, 2–3 mm in length, uniformly serrated, with fimbriate hairs, 7–14 mm long; blades length 6–8 cm × width 0.7–0.9 cm, lanceolate, erect or recurved. Foliage leaves 6–12 per ultimate branch; sheaths leathery, glabrous; auricles reflexed, sickle-shaped, oral setae radiated, 6–12 mm long; ligules ca. 3 mm in length, with white short hairs abaxially, apex truncate or with inconspicuous serrated, with fimbriate long hairs, ca. 1 cm long; blades lanceolate, 16–26 cm × 3–4.5 cm, with white pubescence abaxially, one margin entire, the other with short cilium, secondary veins 10–12 paired. Inflorescence and caryopsis unknown.

Phenology.

New shoots May to August.

Distribution and ecology.

This new species is found in Pingxiang and Congzuo Counties in Guangxi, China. It grows in warm and humid environments and usually occurs in limestone montane areas at altitudes of 100– 300 m.

Etymology.

The epithet originates from Guangxi Autonomous Region where the new species was collected.

Additional specimen examined.

China • Guangxi: Chongzuo City, Pingxiang County, Xiashi Town, Pochatun , 22°11'7.14"N, 106°58'3.98"E, alt. 260 m, 21 Jul 2023, C. Zhang et al. PX 001 .

Note.

In the Skmer tree, sampled individuals of Melocalamus guangxiensis clustered in a clade sister to M. putaoensis . Due to notable morphological differences between M. putaoensis and M. guangxiensis , such as the absence of culm leaf auricles and oral setae, ligules without cilia and the base of outer margin in culm leaf sheaths without a membranous projection in M. putaoensis , we conclude that this species belongs to Melocalamus , but does not fit into any described species. Therefore, we treat it as a new species of Melocalamus .

Figures

Figure 7. Melocalamus guangxiensis D. Z. Li & J. X. Liu A. Habitat; B, C. Branch complement; D. Culm leaf blade; E. A complete internode and culm leaf, showing the culm bud, apex of culm leaf sheath and the base of culm leaf sheath; F. Longitudinal section of main culm; G, H. Foliage leaves and foliage leaf sheath; I. Branchlet.