Fargesia nana F. Du, M. Shi & J. W. Li, 2025

Li, Jian-Wei, Wang, Juan, Shi, Ming & Du, Fan, 2025, Fargesia nana (Poaceae, Bambusoideae), a new bamboo species from Yunnan, China, PhytoKeys 257, pp. 219-233 : 219-233

Fargesia nana F. Du, M. Shi & J. W. Li sp. nov.

Figs 3 , 4

Diagnosis.

Fargesia nana is morphologically similar to F. fractiflexa and Yushania polytricha , but can be easily distinguished by the shortened culm neck (4 ~ 8 cm vs 13 ~ 40 cm in Y. polytricha ), branch complement (10 ~ 20 (30) vs. 1 ~ 5 in Y. polytricha ), culm leaf sheath / internode (1 / 3–1 / 2 vs. longer than internodes in F. fractiflexa , vs. 2 / 3 in Y. polytricha ), culm blade size (0.4 ~ 2 cm × 0.8 ~ 1.7 cm vs. 2 ~ 8 cm × 1 ~ 1.5 mm in F. fractiflexa ), auricle (absent vs. falcate auricle in F. fractiflexa ), foliage leaf size (5 ~ 7 cm vs. 7 ~ 13 cm in F. fractiflexa , vs. 9 ~ 21 cm in Y. polytricha ), foliage leaf sheath length (1.8 ~ 2.2 cm vs. 5.5 ~ 10 cm in Y. polytricha ), transverse veins on foliage leaf blade (conspicuous vs obscure in F. fractiflexa and Y. polytricha ).

Type.

China • Yunna: Chuxiong City, Wuding County, Jiyi Town, Jiyi Rift valley , 26°5'25.9"N, 102°15'52.7"E, 1916 m alt. 28 September 2021, M. Shi et al. 0072410 (Holotype: SWFC!), 0072411 (Isotype: SWFC!) .

Description.

Rhizomes pachymorph, neck 4–8 cm long and 0.6–0.8 cm in diameter; internodes 3–5 mm long. Culms 1–1.5 (2.2) m tall, erect, sympodial, 2–4 (6) mm in diameter; culm wall 1–2 (3) mm thick, cavity small or solid; culm with 10–15 (18) nodes, internodes terete, 10–19 (22) cm long, glabrous, without white powder and longitudinal ribs; supranodal ridge more prominent than the sheath scar, intranodes 2 mm tall. Culm buds 5–8, without obvious main buds, aggregated into a semi-orbicular composite bud. Culm branches 10–20 (30), with slender secondary branches, nearly equal, less than 1 mm in diam., 20–40 cm long. Culm leaf sheaths 5–11 cm long, 1 / 3 to 1 / 2 as long as internodes, caducous, papery, light yellow-brown, narrow triangular, abaxial surface sparsely brown bristled on upper part, glabrous below; auricles and oral setae absent; ligule ca. 2 mm tall, 2–3 mm wide, truncate or lacerated at apex; blade 0.4–2 cm long, 0.8–1.7 cm wide, reflexed, linear-triangular. Foliage leaves 4–6 per ultimate branch; sheath 1.8–2.2 cm long, with obvious longitudinal veins, margins without cilia; auricles and oral setae absent; ligule truncate, ca. 1 mm tall, glabrous; petiole 2–3 mm long; blade narrowly lanceolate, 5–7 cm long and 5–7.5 mm wide, apex long acuminate, base cuneate, sparsely gray-pilose adaxially when young, glabrescent, secondary veins (2) 3 pairs, transverse veins conspicuous. Inflorescence and caryopsis unknown.

Phenology.

New shoots August to September.

Distribution and habitat.

Fargesia nana was only found in Wuding County, Central Yunnan, China. It grows frequently in relatively humid habitats on steep cliffs at an altitude of 1895–1926 m, while coexisting with other herbs and bushes, such as Paradombeya sinensis Dunn , Sunhangia yunnanensis (Franch.) H. Ohashi & K. Ohashi , Heteropogon contortus (L.) P. Beauv. ex Roemer & Schult . Cymbopogon distans (Nees ex Steud.) Will. Watson , Dalbergia yunnanensis Franch.

Etymology.

The specific epithet “ nana ” refers to the morphological characteristics of bamboo species and represents the smallest bamboo species.

Chinese name.

Jǐ Yī Jiàn Zhú (Chinese pronunciation); 己衣箭竹 (Chinese name).

Conservation status.

Fargesia nana is an extremely rare species, and we only found three small populations in the Jiyi Rift Valley, with a total population of about 50–100 individuals. According to the IUCN Red List Categories and Criteria ( IUCN 2024), it meets the criteria to be listed as Critically Endangered (CR A 2 acde; B 2 ab; C 2 a (i )). Given the extremely dry habitat, this new species can only survive in small, relatively moist environments within the canyon. Furthermore, Fargesia nana is the smallest known species of Fargesia , possessing significant conservation and scientific research value.

Additional specimens examined (paratypes).

China • Yunnan: Wuding County, Jiyi Town, Jiyi Rift valley , 26°5'25.0"N, 102°15'54.1"E, 1916 m alt. 28 September 2021, M. Shi et al. 0072412 ( SWFC!) .

Figures

Figure 3. Fargesia nana F. Du, M. Shi & J. W. Li A habitat B habit C leafy branch D branches E culm leaf, showing details of blade and ligule F rhizome G culm bud H culm leaves I new shoot.

Figure 4. Fargesia nana F. Du, M. Shi & J. W. Li A rhizome B branches C culm bud D part of culm, showing culm leaf E foliage leaf sheath and ligule F culm leaf.