Schizostachyum strictum (R.Parker) Naithani & Bennet (1991: 68)

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 : 281-283

(14) Schizostachyum strictum (R.Parker) Naithani & Bennet (1991: 68) . Figs. 3N–Q .

≡ Neohouzeaua stricta R. Parker (1928: 97–98 , pl. 9), as `stricta `.

Type: — MYANMAR, Tavoy, Tenasserim River, 11 January 1927, R.N. Parker 2408 (lectotype designated by Goh et al. (2020: 118): K [K000912103!]).

Description: — Culms erect, 5–15 m high, tips drooping; internodes green when young, bright to yellowish green when mature, 50–80(–150) cm long, 2–5(–8) cm in diameter, covered with white to grey appressed hairs mixed with thin white wax, to glabrous; walls 3–4 mm thick; nodes with slightly prominent nodal line. Culm leaves: sheaths initially green, yellowish-green, greenish-yellow to yellowish, later pale orange, 20–40 cm long, apex symmetrical, concave, base of outer margin with a tiny projection 1–3 mm wide, margins scarious, densely covered with white to pale grey appressed hairs mixed with thin white wax; auricles inconspicuous or narrow rims, oral setae 0.5–1.5 cm long; ligules 1–2 mm high, irregularly toothed, bristly, bristles 1–1.5 mm long; blades spreading to more or less deflexed, yellowish-green to green, linear-lanceolate, 20–40 cm long, usually hairy on adaxial side. Foliage leaves: auricles inconspicuous, oral setae up to 7 mm long; ligules 0.5–1 mm high, irregularly toothed, bristly, bristles up to 3 mm long; blades 10–35 × 1.5–4.5 cm, sparsely hairy to glabrous on adaxial side, hairy to almost glabrous on abaxial side. Pseudospikelets congested as more or less densely globose clusters, purple to purplish-green, narrowly fusiform, 1.5–1.8(–2) cm long; rachilla internodes 1.5–3 mm long; fertile florets solitary, 1.5–2 cm long, usually with terminal rachilla extension 3–5 mm long, and without a vestigial floret; lemmas tightly convolute, 1–1.3 cm long, glabrous; paleas tightly convolute, 1.2–1.6 cm long, not keeled, glabrous. Lodicules absent. Stamens: anthers purplish yellow to purplish green, 4–6 mm long; filaments fused.

Distribution and ecology: — Schizostachyum strictum exists in mixed deciduous and semi-evergreen forests at 170– 500 m.

Additional specimens examined: — THAILAND: South-western. Kanchanaburi, Thong Pha Phum , 27 August 2010, S. Sungkaew & A. Teerawatananon 1238 (Thailand Natural History Museum) ; the same locality, 7 October 2022, S. Sungkaew & A. Teerawatananon 1721 (Thailand Natural History Museum) ; the same locality, 7 October 2022, S. Sungkaew & A. Teerawatananon 1722 (Thailand Natural History Museum) ; the same locality, 23 September 2023, S. Sungkaew & A. Teerawatananon 1809 (Thailand Natural History Museum) ; the same locality, 23 September 2023, S. Sungkaew & A. Teerawatananon 1815 (Thailand Natural History Museum) .

Conservation status: — Schizostachyum strictum has a relatively small EOO of less than 20,000 km 2 (7,377.4 km 2) which places it in the Vulnerable (VU) conservation category while a small AOO of less than 500 km 2 (64.0 km 2) places it in the Endangered (EN) category. As the number of populations and individuals is relatively limited, it therefore faces a high risk of extinction in the wild. According to IUCN (2023) criteria, the conservation status of S. strictum is assessed as Vulnerable [VU B1, B2c (iv)].

Vernacular name: —ไผ่ ทวอยน้อย (Phai Tavoy Noi).

Notes: — Schizostachyum strictum was first discovered in Myanmar in 1927 by R.N. Parker. This official new record in Thailand expands the known distribution range of this species. According to the protologue, Parker (1928) mentioned that the spikelets of S. strictum (under the name Neohouzeaua stricta R. Parker ) bear 3–4 small glumes. However, the structure of Schizostachyum inflorescence had been misinterpreted and the term ‘glumes’ in fact refers to bracts subtending buds and not the empty glumes ( McClure 1934).

(15) S chizostachyum zollingeri Steudel (1854: 332) . Figs. 2G–H . ≡ Melocanna zollingeri Kurz (1866: 20) . Nomen ≡ Melocanna zollingeri Kurz ex Munro (1868: 134) ≡ Melocanna zollingeri (Kurz) Kurz (1870: 88 , pl. 7, fig. 2). Type: — INDONESIA, Java, Jawa Barat, Bandung, Zollinger 3529 (lectotype here designated:P [P00633845, digital image!]; isolectotypes:

G [G00176513 & G00176514, digital images!], MPU [MPU00176514, digital image!], P [P00633842, P00633843, P00633844,

P00633846, digital images!], BM [BM000959294, digital image!], L [L0050081, digital image!]).

Description: — Culms erect, 10–17(–20) m high, tips drooping; internodes green when young, greyish green to green when mature, 40–70(–80) cm long, 2–10 cm in diameter, covered with white wax and white, dark brown to dark hairs; walls 3–7 mm thick; nodes with slightly prominent nodal line. Culm leaves: sheaths pale yellow to yellowish brown, orange to brownish-orange throughout, 10–30 cm long, apex symmetrical, concave, densely covered with appressed dark brown to shining black hairs on abaxial side; auricles undulate or plicate lobed, (3–) 5–10 mm high, oral setae 4–15 mm long; ligules 0.5–1 mm high, subentire, ciliate; blades erect, initially yellowish brown, yellowish green to purplish orange green, cordate or broadly triangular, 7–9 cm long, conspicuously inflated, covered with pale hairs on abaxial side. Foliage leaves: auricles inconspicuous to tiny lobes, oral setae up to 1.5 cm long; ligules up to 0.5 mm high, subentire, ciliate; blades (10–)15–30(–40) × 2–4(–6.5) cm, glabrous to slightly hairy on both sides. Pseudospikelets green, lanceolate, 1–2 cm long; empty glumes 1; rachilla internodes very short; fertile florets solitary, 0.9–1.6 cm long, with terminal rachilla extension, 5–6.5 mm long, with a vestigial floret ca. 0.5 mm long; lemmas 0.7–1 cm long, sparsely hairy toward apex on both sides, sometimes glabrous; paleas 0.7–1.5 cm long, keeled to not keeled, sparsely hairy toward apex on both sides, sometimes glabrous. Lodicules 3. Stamens: anthers yellow, purplish brown to greenish brown, 3.5–5 mm long; filaments free.

Distribution and ecology: —In Thailand, S. zollingeri is distributed in southern Thailand in evergreen forests and it is commonly found in Malaysia and Indonesia.

Additional specimens examined: — THAILAND: South-western. Prachuap Khiri Khan, Thap Sakae , 26 November 2022, S. Sungkaew & A. Teerawatananon 1764 (Thailand Natural History Museum). South-eastern. Trat, Ko Chang, 12 August 2022, S. Sungkaew & A. Teerawatananon 1700 ( Thailand Natural History Museum) ; Ko Kut , 9 April 2002, C. Phengklai 13610 ( BKF134132 ) ; the same locality, 10 November 2022, S. Sungkaew & A. Teerawatananon 1754 ( Thailand Natural History Museum). Peninsular. Surat Thani, Phanom, 12 July 2004, S. Sungkaew & A. Teerawatananon 2004-0113 ( Thailand Natural History Museum) ; the same locality, 22 October 2022, S. Sungkaew & A. Teerawatananon 1735 ( Thailand Natural History Museum) ; the same locality, 14 December 2009, C. Rattamanee M205 (BKF197518, BKF197158 ) ; Ratchaprapa Dam , 21 February 2001, S. Sungkaew & R. Pattanavibool 3 ( BKF132207 ) ; Phangnga, Khao Phra Mi , 9 January 1996, B. Hansen & T. Smitinand 11849 ( BKF36993 ) ; Nop Pring , 23 January 2001, S. Sungkaew & R. Pattanavibool 9 ( BKF132205 ) ; Phuket, Khao Pha Thaew , 27 February 1994, C. Niyomdham & W. Ueachirakan 3543 ( BKF123642 ) ; Krabi, Khao Pra Bangkram , 15 February 1991, C. Niyomdham 2101 ( BKF118549 ) ; Khlong Thom ( Klong Tawm ), 12 April 1996, S. Dransfield SD 1404 ( BKF111035 , L1328386 ) ; the same locality, 7 October 2005, J.F. Maxwell 05-559 ( BKF160014 ) ; the same locality, 9 July 2004, S. Sungkaew & A. Teerawatananon 2004-0070 ( Thailand Natural History Museum) . SINGAPORE: Pasir Panjang , 10 December 1934, R.E. Holttum s.n. ( SING0017831 ) ; the same locality, 11 December 1934, Klah s.n. ( SING0054950 ) . MALAYSIA: Genting , 14 March 1948, R.E. Holttum SFN38414 ( SING0330156 ) ; Kepong , 26 September 1980, S. Kamarudin FRI30401 ( SING0330132 ) ; Perak, 4 April 1934, J. L. Pestana 28431 ( SING0330143 ) ; Perlis, 17 February 1981, K.M. Wong FRI32102 ( SING0330133 ) .

Conservation status: — Schizostachyum zollingeri has an EOO of approximately 47,000.0 km 2 which puts it in the Least Concern (LC) conservation category while its small AOO of less than 500 km 2 (224.0 km 2) yields the Endangered (EN) category. There are many populations with many individuals commonly found both inside and outside protected areas over large areas. Here, we therefore consider the conservation status of S. zollingeri is LC according to IUCN (2023) criteria.

Vernacular name: —ไผ่กาบแดง (Phai Gab Daeng), ไผ่เกรียบ (Phai Kriab), ไผ่โป (Phai Po), ไผ่โปะ (Phai Poh), ไผ่เมี่ ยงไฟ (Phai Miangfai).

Notes: — Schizostachyum zollingeri is morphologically similar to S.brachycladum , which was treated as Melocanna zollingeri var. brachycladum Munro. Holttum (1958) suggested that Javan plants ( S. zollingeri ) and Peninsular plants ( S. brachycladum ) should be different species. Schizostachyum zollingeri bears prominent culm leaf sheath auricles with long oral setae and several glumes in its pseudospikelets. In contrast, S. brachycladum has relatively small auricles and absence of glumes in its pseudospikelets. In recent systematic work, parallel phylogenetic analyses agree that S. brachycladum and S. zollingeri are separate species ( Yang & Li, 2007; Yang et al. 2008; Zhou et al. 2022).

Nomenclatural notes: —In the protologue, Steudel (1854) provided the description of S. zollingeri from the specimens labeled as “ Bambusa nr. 3529. Hrbr. Zollinger. Java”. There are eight possible type duplicates matching with the detailed description and specimen labels in the protologue and they are deposited in BM, G, L, MPU and P. According to Stafleu and Cowan (1985), the majority of type specimens designated by Steudel are deposited in P and PC in Paris and some of them are at CN, K, L, PH and STR. We examined the labels on these type specimens and found that there are only two specimen labels in G (G00176513) and P (P00633845) written with Steudel’s handwritings ( Cayouette & Darbyshire 1994). With the information above, we have selected the specimen with the barcode P00633845 as the lectotype since it represents the best-preserved specimen.

Figures

FIGURE 2. (A–B) Schizostachyum brachycladum (Kurz) Kurz. (A) Culm internode with culm leaf; (B) Young culm shoot. (C–D) S. grande Ridl. (C) Young culm shoot; (D) Culm leaf on culm internode. (E–F) S. pergracile (Munro) R.B.Majumdar. (E) Culm internode with culm leaf; (F) Young culm shoot. (G–H) S. zollingeri Steud. (G) Culm leaf on culm internode; (H) Young culm shoot. (I–L) S. chinense Rendle. (I) Clump habit; (J) Young culm shoot; (K) Young culm showing culm leaf characteristics (with concave and inflated apex of the sheath proper, and erect blades) and a node; (L) Flowering branch. (Photographed by A. Teerawatananon & S. Sungkaew).

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).