Deyeuxia gaoligongensis B.Paszko, 2013

Paszko, Beata & Pendry, Colin, 2013, Deyeuxia gaoligongensis (Poaceae: Agrostidinae), a new species from Gaoligong Shan in Yunnan, China, Phytotaxa 93 (1), pp. 40-46 : 41

Deyeuxia gaoligongensis B.Paszko , sp. nov. ( Figs 1–4 )

Differs from Deyeuxia debilis by its well-developed lemma awn that is twisted at the base, geniculate, and inserted on the lower half of the back of the lemma.

Type: — CHINA. Yunnan: Gongshan Xian [Cikai Zheng], track from Qiqi towards Dulongjiang (3000 m up to 3750 m), damp south-facing bank in boulder field in degraded open forest with Abies and Larix , 3300 m, 27º41'30ʺN, 98º27'25ʺE, 15 October 1996, Gaoligong Shan Expedition 1996 no. 7753 (holotype, E 00146585!).

Perennial, tufted, culms 10–32 cm tall, erect to decumbent at the base, nodes 2–3. Culm blades 1.3–8 cm long, 0.5–2.2 mm wide, upper leaf surface moderately ribbed and scabrous, leaf collar glabrous, ligules 1.5–2.2 mm long, oblong. Panicles 1.5–7 cm long, pyramidal, contracted to open, erect, with 5–60 spikelets, branches 0.7– 4 cm long, slightly scabrous, 3–7 nodes, 2–4 branches per node, pedicels distally slightly expanded 0.3 mm just below the spikelet. Spikelets 1-flowered, laterally compressed, long-pedicelled; glumes equal or subequal, smooth, or only slightly scabrous in the upper part over the midvein, apices acute, lower 3.3–4.5 mm long, 0.95–1.20 mm broad, 1-veined, upper 3.1–4.4 mm long, 0.85–1.05 mm broad, 0.93–1 × the length of the lower glume, 3-veined; callus hairs 2.5–3.5 mm long, 0.95–1.32 × the length of the lemma, surrounding the floret; lemmas 2.2–2.8 mm long, 5-veined, 0.58–0.71 × the length of the lower glume, apex 2–4-toothed or with 2 short mucros, ca. 0.3 mm; awn geniculate 4.1–8.2 mm long, twisted (sometimes only slightly twisted) at the base, attached to the lower ⅓–½ of the lemmas, conspicuously exerted from the glumes; palea shorter than lemma, 1.9–2.4 mm long, 0.77–0.91 × the length of the lemma; rachilla prolongation 0.50–0.85 mm long, shortly penicillate or almost glabrous, 1.9–2.2 mm including silky hairs; anthers 3, 0.6–0.9 mm long; caryopsis ca. 1.5 × 0.5 mm, smooth.

Distribution and habitat: — Deyeuxia gaoligongensis occurs in the Gaoligong Shan (sub-range of the southern Hengduan Mountain Range) in northwestern Yunnan, China. It was collected on the eastern slopes of the Gaoligong Shan at elevations between 3300 and 3900 m in two regions of Gongshan Xian: Dulongjiang Xiang and Cikai Zheng (NW Yunnan, China) ( Fig. 4 ). The new species grows in bamboo and Rhododendron thickets on rocky slopes and occasional open areas of meadow or damp south-facing banks in boulder fields in degraded open forest with Abies and Larix . The type collection was collected on the track from Qiqi towards Dulongjiang by Gaoligong Shan Expedition in 1996 at an elevation of 3300 m.

Etymology: —The specific name derives from the name of the mountain range, Gaoligong Shan, where three first localities are recorded.

Similar species: — Deyeuxia gaoligongensis is similar in spikelet morphology to D. debilis and these species could be confused at first sight. However, the former differs by its geniculate awn with a twisted column, arising from the lower half of the lemma back, whereas D. debilis has a straight awn inserted above the midpoint of lemma. These two species apparently sometimes grow in close proximity as one sheet (GSBS 17031) with a mixed collection was found during the course of this study.

Additional specimens: — CHINA. Yunnan: Gongshan Xian [Dulongjiang Xiang]. W side of the pass of the road from Gongshan to Kongdang. E side of Gaoligong Shan, 27º46ʹ16ʺN, 98º26ʹ29ʺE, bamboo and Rododendron thicket with rocky slopes and occasional open areas of meadow, 3750 m, 2 October 2002, Gaoligong Shan Biodiversity Survey ( GSBS) 17031 ( CAS!, in part, mixed with Deyeuxia debilis ; KUN) . [Cikai Zheng]. Salween Irrawaddy divide above Dong Shao Fang Forest Station on Nan Mo Wang Shan. East and west facing slopes, 3800–3900 m, 27º41ʹN, 98º27ʹE, 22 September 1997, Gaoligong Shan Expedition 1997 no. 9450 ( E00107774 !) .

Figures

FIGURE 1. Deyeuxia gaoligongensis (C–G, I drawn from GSBS 17031; A, B, H drawn from Gaoligong Shan Expedition 1996 no. 7753, by Jolanta Urbanik). A. habit; B. sheath, ligule and blade; C. lower and upper glume; D. floret; E. tip of lemma; F. caryopsis; G. anthers; H, I. two types of rachilla prolongations.

FIGURE 2. Holotype of Deyeuxia gaoligongensis (Gaoligong Shan Expedition 1996 no. 7753). With permission of the Keeper of the Royal Botanic Garden Edinburgh.

FIGURE 3. Deyeuxia gaoligongensis. A. upper leaf surface (Gaoligong Shan Expedition 1996 no. 7753); B. caryopsis in lateral view (GSBS 17031). Scale bar = 0.5 mm.

FIGURE 4. Distribution of Deyeuxia gaoligongensis in the Gaoligong Shan region, China, marked in grey.