Chimonocalamus auriculatus

Thai name: No known records.

Distribution: THAILAND (Central): Phitsanulok Province, northernmost part: ภูสอยดาว Phu Soi Dao, a mountain on the border with Laos; grows in moist soils in the understorey of montane forest and along streams at 1,500–1800 m altitude.

Description: "Arborescent bamboo. Rhizomes pachymorph with short necks, forming a clump of culms. Culms erect, 5−7 m tall, 1−3 cm in diam., green and covered with white to gray hairs when young, yellowish-green and glabrous when mature; nodes faintly prominent, glabrous, the basal nodes (from the ground level to nodes 10−15) with a ring of 1−7 mm long root-thorns; internodes terete, 10−27 cm long, walls thin, 2−5 mm thick (mid-culm portion). Branches developing from around the mid-culm upwards. Mid-culm branch complement with 3 sub-equal branches at each node, the middle branch slightly bigger than the 2 side-branches. Culm leaf sheath green, deciduous, 17−26 × 7−10 cm, mottled or blotched when dry, covered abaxially with sparsely appressed brown to dark brown hairs, apex slightly concave to truncate, 5−10 mm wide, margins glabrous; auricles prominent, deltoid lobed, 1.5−3 mm tall, oral setae several, persistent, 0.3−1 cm long; ligule truncate to slightly concave, 2−3 mm tall, margin irregular toothed to fimbriate and fringed with minute cilia; blades purplish-green to green, spreading to slightly recurved, lanceolate-linear, 3−10 × 0.2−0.5 cm. Foliage leaves 3−7 per ultimate branch; sheaths 2−3.5 cm long, glabrous, margins glabrous; auricles prominent, deltoid lobed, 0.25−0.5 mm tall, oral setae 5−9, persistent, 2−5 mm long; ligules convex to slightly truncate, membranous, 0.5−1 mm tall, margin irregular toothed to fimbriate; pseudo-petiole 0.1−0.2 cm long; bladeswith inconspicuous transverse veins, narrowly lanceolate, 5−11 × 0.5−0.9 cm, glabrous both sides, occasionally abaxially sparsely hairy on nerves (particularly those nerves near the blade margins), base acute to attenuate, apex acuminate. Inflorescence unknown." — Sungkaew & al., Chimonocalamus auriculatus, one more new temperate woody bamboo species of the genus (Poaceae: Bambusoideae: Arundinarieae) described from Thailand, in Phytotaxa vol. 357 (1), 2018: p. 66-70 [#1266].

Images: Line drawing and photos in Sungkaew & al., l.c., 2018 [#1266].

Comments: "… In its vegetative state, the new species [Chimonocalamus auriculatus] can be distinguished from all the other Chimonocalamus species by its conspicuous auricles and oral setae (bristles) on the culm leaf sheath." — Abstract in Sungkaew & al., l.c., 2018 [#1266].