Schizostachyun dullooa (Gamble) R.B.Majumdar

Sungkaew, Sarawood, Wong, Khoon Meng, Hodkinson, Trevor R., Thammanu, Siriluck, Cheysawat, Somboon & Teerawatananon, Atchara, 2024, Taxonomic revision of the bamboo genus Schizostachyum (Bambusoideae: Melocanninae) in Thailand, with two new species and five new records, lectotypifications and nomenclatural corrections, Phytotaxa 676 (3), pp. 263-286 : 272

(5) Schizostachyun dullooa (Gamble) R.B.Majumdar (in Karthikeyan et al. 1989: 281). Figs. 3E–I .

≡ Teinostachyum dullooa Gamble (1896: 101 , pl. 89).

Type: — MYANMAR, Katha , Hawgaw Monastery garden, February 1892, Oliver s.n. (lectotype designated by Goh et al. (2020: 117): K [K000710261!]; isolectotypes: K [K000710257, K000710258, K000710259, K000710260, digital images!]) .

Description: — Culms erect, 5–15 m high, tips drooping; internodes dull green when young, green when mature, 45– 120 cm long, 2–10 cm in diameter, covered with pale hairs mixed with thin white wax, almost glabrous when mature; walls 3–5 mm thick; nodes without raised nodal line. Culm leaves: sheaths initially yellowish-green to straw-colored, later straw-colored, 15–30 cm long, apex asymmetrical, concave to more or less truncate, base of outer margin without a projection, (if present, projection less than 2 mm wide), margins scarious, covered with scattered white or pale hairs mixed with thin white wax on abaxial side; auricles narrow rim, oral setae 0.3–1.5 cm long; ligules ca. 1 mm high, irregularly toothed, ciliolate; blades spreading to deflexed, initially purplish green to straw-colored, later straw-colored, linear-lanceolate, 7.5–15 cm long, hairy on adaxial side especially at the base. Foliage leaves: auricles inconspicuous, oral setae 3–7 mm long; ligules up to 0.5 mm high, irregularly toothed, ciliolate; blades 10–25 × 2–4 cm, sparsely hairy on both sides. Pseudospikelets purple to purplish-green, fusiform, 1.3–2.5(–3) cm long; rachilla internodes up to 3 mm long; fertile florets 1, 2–2.2 cm long, with terminal rachilla extension, 1.5–1.7 cm long, and sometimes with a tiny vestigial floret; lemmas convolute, 1–1.5 cm long, short hairs all over; paleas convolute, 1.8–2.2 cm long, not keeled, scabrid near the apex. Lodicules absent. Stamens: anthers yellow, 8–9 mm long; filaments fused.

Distribution and ecology: —The occurrence of S. dullooa in Thailand accords with its continuous distribution range in mainland Southeast Asia since previous records were documented in India, Bangladesh, Bhutan, Myanmar and Vietnam ( Camus 1922; Gamble 1896; 1923; Stapleton 1994). Populations in Bhutan and Myanmar were found at altitudes from around 700–1,800 m ( Gamble 1896). Likewise, S. dullooa exists in Thailand at altitudes from 200– 1,600 m and grows in semi-evergreen and lower montane forests.

Additional specimens examined: — THAILAND: Northern. Chiang Mai, Doi Sutep-Pui National Park , 30 November 1999, J.F. Maxwell 99-310 ( L0399435 , L0399436 , L0399437 , L0399438 ) ; Fang, Mae Ngon , 27 September 2003, S. Sungkaew & A. Teerawatananon 2003-0198 ( Thailand Natural History Museum) ; Phayao, Mueang Phayao, Ban Tam , 21 July 2001, S. Sungkaew 210701-07 ( Thailand Natural History Museum) ; Nan, Bor Gluea , 27 October 2009, C. Rattamanee M185 ( BKF197499 ) ; Lamphun, Toong Hoa Chang , 27 February 2000, J.F. Maxwell 00-114 ( L0399430 , L0399431 , L0399432 , L0399433 ) ; Uttaradit, Mueang Uttaradit, Ban Dan Na Kham , 28 October 2022, S. Sungkaew & A. Teerawatananon 1752 ; Phitsanulok, Si Satchanalai, 6 February 1988, T. Smitinand s.n. ( BKF087390 ). North-eastern. Phetchabun, Tard Mok National Park , 11 August 2008, C. Rattamanee M037 ( BKF197418 ) ; Loei, Phu Ruea , 11 September 2009, C. Rattamanee M165 ( BKF199312 ). South-western. Ratchaburi, Suan Phueng, Khao Krachom, 3 July 2004, S. Sungkaew & A. Teerawatananon 030704-8 ( Thailand Natural History Museum) . LAOS: Nakhon Luang Vieng Chan, Sung Thong , 8 April 2005, S. Sungkaew & A. Teerawatananon 443 (Thailand Natural History Museum) .

Conservation status: — Schizostachyum dullooa has an EOO of 164,196.8 km 2 which places it in the Least Concern (LC) conservation category while its small AOO of less than 500 km 2 (56.0 km 2) yields the Endangered (EN) category. However, there are many populations commonly found in gaps and edges of semi-evergreen and lower montane forests in protected areas in wide geographic and altitudinal ranges, hence, it is unlikely that this species would encounter many threats. Based on IUCN (2023), the conservation status of S. dullooa should be categorized as LC.

Vernacular name: —ไผ่โพ (Phai Po), ไผ่เฮียะ (Phai Hia), ไผ่เหลือง (Phai Lueang).

Notes: — Schizostachyum dullooa is reported here as an official new record in Thailand. Previously, this bamboo was misidentified as S. virgatum (Munro) Naithani & Bennet (1991: 68) ( Sungkaew et al. 2011).

Figures

FIGURE 3. (A–B) Schizostachyum fimbriatum (S.Dransf., Pattan. & Sungkaew) K.M.Wong. (A) Part of leafy branch; (B) Young culm with culm leaf attached. (C–D) S. kerrianum (S.Dransf., Pattan. & Sungkaew) K.M.Wong. (C) Part of leafy branch; (D) Young culm with culm leaf attached. (E–I) S. dullooa (Gamble) R.B.Majumdar. (E) Young culm shoot; (F & G) Different aspects of culm leaves; (H) Part of leafy branch; (I) Flowering branch. (J–M) S. helferi (Munro) R.B.Majumdar. (J) Young culm shoot; (K) Young culm with culm leaf attached; (L) Part of leafy branch; (M) Flowering branch. (N–Q) S. strictum (R.Parker) H.B.Naithani & Bennet. (N) Young culm shoot; (O) Culm leaf; (P) Part of leafy branch; (Q) Pseudospikelet cluster on flowering branch. (Photographed by A. Teerawatananon & S. Sermsinchaisakul).