Schizostachyum helferi (Munro) 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 : 273-275

(8) Schizostachyum helferi (Munro) R.B.Majumdar (in Karthikeyan et al. 1989: 281). Figs. 3J–M .

≡ Bambusa helferi Munro (1868: 114) .

Type: — MYANMAR, Tenasserim, 1839, Helfer 411 (not Griffith 6719, fide Goh et al. 2020) (holotype: K [K000912110!]. Supported by epitype: MYANMAR, Toungoo, Thandaung Forest, 31 May 1922, R.S. Hole s.n. (epitype here designated: K [K003901395!]).

Description: — Culms erect, 5–15 m high, tips drooping, occasionally clambering on other vegetation; internodes dark green throughout, 45–90(–120) cm long, 1.5–5 cm in diameter, covered with brown to black hispid hairs near the node and white hairs on the lower portion; walls 3–5 mm thick; nodes without prominent nodal line, below the nodes with a band of thin white wax and strigose hairs. Mid-culm branch complements with one dominant primary branch, and a dense cluster of several slender subequal higher-order branches per node. Culm leaves: sheaths initially green, yellowish green to green, 16–26 cm long, apex symmetrical, truncate, margins scarious, base of outer margin without a projection (if present, projection less than 5 mm wide), covered with white hispid hairs on abaxial side; auricles inconspicuous, oral setae 2.0– 2.5 cm long; ligules up to 1 mm high, irregularly toothed, bristly, bristles up to 2 cm long; blades spreading to finally deflexed, green throughout, narrowly lanceolate, 4–14 cm long, hairy on adaxial side. Foliage leaves: auricles inconspicuous, oral setae 1.5–2 cm long; ligules less than 0.5 mm high, irregularly toothed, bristly, bristle up to 1 cm long; blades 15–45 × 2.5–7.5 cm, glabrous on both sides. Pseudopikelets green to purplish-green, fusiform, 3–4.7 cm long; rachilla internodes up to 1 mm long; fertile florets 1, 3–4.5 cm long, terminal rachilla extension usually absent; lemmas convolute, lanceolate, 2.1–2.8 cm long, densely hairy at upper half part; paleas convolute around the floret, 3.0– 4.5 cm long, not keeled, hairy at the apex. Lodicules absent. Stamens: anthers reddish brown, 1.2–1.7 cm long; filaments fused.

Distribution and ecology: — Schizostachyum helferi occurs in highland areas (900–1,200 m a.s.l.) of India and Myanmar ( Gamble 1923). We have discovered two additional populations of S. helferi in Thailand growing on the Tenasserim Hills range near the Thai-Myanmar border in Kanchanaburi and Tak Provinces. This bamboo inhabits only in moist areas, forest edges and gaps of semi-evergreen and lower montane forests at high altitude above 700 m.

Additional specimens examined: — THAILAND: Northern. Tak, Tha Song Yang, Mae Wa Luang , 8 December 2023, S. Sungkaew & A. Teerawatananon 1823 (Thailand Natural History Museum) ; the same locality, 8 December 2023, S. Sungkaew & A. Teerawatananon 1824 ( Thailand Natural History Museum) ; the same locality, 8 December 2023, S. Sungkaew & A. Teerawatananon 1825 ( Thailand Natural History Museum). South-western. Kanchanaburi, Thong Pha Phum, 23 July 2004, S. Sungkaew & A. Teerawatananon 44 ( Thailand Natural History Museum) ; the same locality, 3 November 2005, S. Sungkaew & A. Teerawatananon 668 ( Thailand Natural History Museum) ; the same locality, 23 September 2023, S. Sungkaew & A. Teerawatananon 1812 ( Thailand Natural History Museum) ; the same locality, 23 September 2023, S. Sungkaew & A. Teerawatananon 1813 ( Thailand Natural History Museum) ; the same locality, 23 September 2023, S. Sungkaew & A. Teerawatananon 1814 ( Thailand Natural History Museum) . MYANMAR: Bago, Toungoo, North Thandaung Division , 31 May 1921, the Forest Ranger s.n. (K003901392) ; the same locality, 31 May 1921, R.S. Hole s.n. (K003901395) ; Karen Hills , 8 June 1921, R.S. Hole s.n. (K003901404) ; the same locality, S. Kurz 3185 (CAL0000002830, CAL0000002831 ) ; Thandaung Forest , 26 March 1922, Ranger officer Toungoo s.n. (K003901389, K003901390, K003901391, K003901394, K003901396) ; Pegu, Yomah , E. and W. Slopes, 4 February 1871, S. Kurz 3186 ( CAL0000002836 ) . INDIA: Meghalaya, Khasia , September 1889, G. Mann s.n. ( CAL0000002801 ) .

Conservation status: — Schizostachyum helferi has an EOO of 24,494.9 km 2 which places it in the Near Threatened (NT) conservation category while its AOO of 84.0 km 2 (i.e., less than 500 km 2) puts it in the Endangered (EN) category. Although the number of populations is relatively limited, they are in protected areas where the threats are unlikely to affect the existing population size. According to IUCN (2023) criteria, we therefore consider the conservation status of S. helferi is NT.

Vernacular name: —ไผ่ทวอยใหญ่ (Phai Tavoy Yai).

Notes: —Two populations of S. helferi mark a new record in Thailand on the Tenasserim Hills range and are the southernmost distributions of the species. Schizostachyum helferi shows morphological affinity to S. strictum and S. tavoyanum and they are also distributed on the Tenasserim mountain range. Our observations show that quantitative differences in characters are the most noticeable when we compare S. helferi to S. strictum and S. tavoyanum . Schizostachyum helferi possesses larger lemmas and paleas and longer anthers and styles than the other two species. Schizostachyum helferi has longer pseudospikelets, longer anthers and denser hairs on pseudospikelets than the ones of S. tavoyanum .

Nomenclatural notes: —The basionym Bambusa helferi was published by Munro (1868),who described diagnostic characters from a collection of J.W. Helfer (no. 411) in “Ind. or. Tenasserim”. In 1896, the name Teinostachyum helferi was published by Gamble based on the B. helferi collection and the flowering collections of G. Mann from India. Gamble (1923) further provided a full description using flowering materials collected by R.S. Hole from Myanmar and made a nomenclatural combination to yield a new name Neohouzeaua helferi . The type specimen of B. helferi was checked and shows severely degraded plant parts and thus is in too poor a state to provide sufficient morphological information. Here, proposing an epitype to complement the holotype is necessary ( Turland et al., 2018). We have found ten duplicates of a flowering specimen matching the information of Gamble (1923) at K (K003901388, K003901389, K003901390, K003901391, K003901392, K003901394, K003901395, K003901396, K003901404, K003901408). According to Article 9.9 of the Shenzhen Code, we here select the specimen with barcode K003901395 as the epitype, as this was used by Gamble (1923) to write the description.

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).