Schizostachyum cambodianum Merkl., Chhang & K.M.Wong

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 : 270-271

(3) Schizostachyum cambodianum Merkl., Chhang & K.M.Wong (in Merklinger et al. 2017: 84, figs. 1, 2). Figs. 1K–M .

Type: — CAMBODIA, Veal Viang District , Phnom Samkos Wildlife Sanctuary, Yai Mau Shrine area, alt. ca. 875 m, 12° 12’ 38.6” N, 102° 53’ 55.2” E, 25 November 2015, Merklinger FFM 2015-76 (holotype: SING [SING0285986, SING0285987, SING0285988!]; isotypes: K & Forestry Administration Cambodia) .

Distribution and ecology: —The known distribution range of S. cambodianum , so far, covers the southwestern part of Cambodia in Pursat and Ko Kong Provinces and southeastern Thailand in Trat Province where its small population exists in an evergreen forest.

Additional specimens examined:— THAILAND: South-eastern. Trat, Ko Kut , 9 November 2005, A. Teerawatananon & S. Sungkaew 691 (Thailand Natural History Museum) ; the same locality, 3 April 2006, A. Teerawatananon & S. Sungkaew 918 ( Thailand Natural History Museum) ; the same locality, 10 November 2022, S. Sungkaew & A. Teerawatananon 1760 ( Thailand Natural History Museum) ; the same locality, 10 November 2022, S. Sungkaew & A. Teerawatananon 1762 ( Thailand Natural History Museum) ; the same locality, 10 November 2022, S. Sungkaew & A. Teerawatananon 1763 ( Thailand Natural History Museum) . CAMBODIA: Koh Kong Province, 18 August 2016, F.F. Merklinger 2016-17 (SING0282012, SING0282013 ) ; Pursat Province, Phnom Sam Los Wildlife Sanctuary , March 2015, F.F. Merklinger 2015-47 (BKF210512, SING0245535 ) .

Conservation status:— Schizostachyum cambodianum has a very small EOO of less than 100 km 2 (28.8 km 2) which places it in the Critically Endangered (CR) conservation category while a small AOO of less than 500 km 2 (28.0 km 2) places this species in the Endangered (EN) category. This bamboo species occurs on a small island “Ko Kut (Kut Island)” in Trat Province, Thailand. This can be regarded as a single severely fragmented population. According to IUCN (2023), we consider the conservation status of S. cambodianum Critically Endangered [CR B1, B2a].

Vernacular name:— ไผ่กะแสนย้อย (Phai Kasaen Yoi).

Notes: — Schizostachyum cambodianum was first described from the Cardamom Mountains in Cambodia. This is a new record for Thailand. Schizostachyum cambodianum found on Ko Kut (Kut Island) shows some morphological differences from the populations found in the Cardamom Mountains ( Merklinger et al. 2017) such as having a faintlykeeled palea and more hairs on the culm and leaf sheath.

Figures

FIGURE 1. (A–E) Schizostachyum aciculare Gamble. (A) Young culm showing culm leaf sheath, node and parts of internodes; (B) Culm leaf sheath apex; (C) Young culm shoot; (D) Part of leafy branch; (E) Flowering branches. (F–J) S. kohchangense W.Arthan, Teerawat. & Sungkaew, sp. nov. (F & J) Young culms showing culm leaf sheaths; nodes and parts of internodes; (G) Young culm shoot; (H) Part of leafy branch; (I) Flowering branches. (K–M) S. cambodianum Merkl., Chhang & K.M.Wong. (K) Young culm showing culm leaf sheath, nodes and parts internodes (note basal projection from the outer margin of the culm sheath proper); (L) Flowering branch; (M) Close-up of culm node with primary branch bud. (N–P) S. nigrum W.Arthan, Teerawat. & Sungkaew, sp. nov. (N) Flowering branch; (O) Close-up of culm node with the characteristic ring of hairs; (P) Young culm showing culm leaf sheath (note basal projection of outer margin), node and parts internodes. (Photographed by A. Teerawatananon & D. Pathumthong).