Ptilagrostis contracta Z. S. Zhang & W. L. Chen, 2017

Zhang, Zhong-Shuai, Li, Ling-Lu & Chen, Wen-Li, 2017, Ptilagrostis contracta (Stipeae, Poaceae), a New Species Endemic to Qinghai-Tibet Plateau, PLoS ONE (e 0166603) 12 (1), pp. 1-10 : 3-7

Ptilagrostis contracta Z. S. Zhang & W. L. Chen , sp. nov. [urn:lsid:ipni.org:names: 77158315–

1] ( Fig 1 and Fig 3 ).

Type: — CHINA. Sichuan: Litang , 3701 m, 26 September 2014, Z. S. Zhang & L. L. Li 341

( holotype PE!) .

Diagnosis. Ptilagrostis contracta differs from the other species of Ptilagrostis in having contracted panicles, 1-geniculate awns with hairy columns and scabrous bristles and evenly pubescent lemmas. In gross morphology, the new species resembles to P. yadongensis Keng

f. & J. S. Tang and Stipa subsessiliflora (Rupr.) Roshev. ( Ḛ Ptilagrostis subsessiliflora (Rupr.) Roshev. ) [ 6, 25, 26] in having contracted panicles. For distinguishing these 3 narrow panicled species, a key is provided here.

Key to Ptilagrostis contracta , P. yadongensis and Stipa subsessiliflora

Description. Perennial, densely tufted, basal branching intravaginal; culms erect, 60–105 cm tall, ca. 2–3 mm in diameter, 3-noded. Leaf sheaths nearly smooth; leaf blades slender, fold, up to 43 cm, 0.6–1 mm wide, nearly smooth; ligule lanceolate, 1–2.5 mm. Panicles contracted, 13–31 cm long; branches often paired, appressed to the rachis, pulvinae at the base of the branches absent; lower part bare, upper part with few spikelets. Spikelets 10–14 mm long, yellowish-brown or purple at base; glumes subequal, lanceolate-oblong, membranous, hyaline, midrib obvious, lateral veins inconspicuous, lower 10–14 mm long, upper 10–14 mm long; calluses obtuse, ca. 0.5 mm long; lemmas 6–9 mm long, evenly pubescent with hairs ca. 0.5 mm long, apex 2-toothed, teeth 0.3–1 mm long; awns persistent, 1.3–2.0 cm long, 1-geniculate, columns twisted, hairs ca. 0.5–0.7 mm long, bristles scabrous, hairs ca. 0.1 mm long; paleas subequal to lemmas; anthers ca. 2.5 mm long, bearded at apex.

Etymology. The epithet contracta refers to the contracted panicles. Chinese name: AE" DZM̔.

Distribution and habitat. Ptilagrostis contracta grows under the birch forests or in the

Rhododendron thickets at about alt. 3500–4300 m. It is endemic to Qinghai-Tibet Plateau and currently found only in Sichuan province, China ( Fig 4 ) .

Phenology. Flowering and fruiting from July to October.

Conservation Status. Ptilagrostis contracta is currently known from 9 locations in Sichuan province within the regions of Dawu, Kangding, Litang and Zamtang. The number of mature individuals is estimated to be ca. 18,000 in the populations. The populations in Kangding and Litang are all close to roads or villages in habitats seriously disturbed by human activities. One population in Kangding ( Z. S. Zhang & L. L. Li 375) possesses no more than 20 mature individuals. The population size of P. contracta will likely drop to 10,000 in the near future and is close to qualifying for a Vulnerable ( VU) species according to the criteria C ( IUCN red list categories and criteria, Version 3.1, Second edition) [ 27]. So P. contracta was categorized as a Near Threatened ( NT) species ( A taxon is Near Threatened when it has been evaluated against the criteria but does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for or is likely to qualify for a threatened category in the near future) [ 27].

Additional specimens examined. CHINA. Sichuan: Daocheng Xian & Litang Xian, Heitze-shan, 3700 m, 29 August 1934, C. S. Liu 1425 ( PE); Dawu Xian, 4300 m, 15 September 1974, Anonymous 5974 ( PE); Kangding Xian, 3574 m, 28 September 2014, Z . S . Zhang & L. L. Li 366 ( PE); Kangding Xian, 3545 m, 28 September 2014 , Z. S. Zhang & L. L. Li 371 ( PE); Kangding Xian, 3924 m, 29 September 2014, Z. S. Zhang & L. L. Li 375 ( PE); Litang Xian, 3728 m, 24 September 2014, Z. S. Zhang & L. L. Li 336 ( PE); Litang Xian, 4100 m, 24 September 1973, Sichuan Vegetation Survey Team 3987 ( PE, N, KUN); Zamtang Xian, 4100 m, 17 July 1975, Anonymous 932* ( PE).

Figures

Fig 1. Ptilagrostis contracta. A-B. habitat; C. contracted panicle; D. base of panicle branch (pulvinae absent); E. spikelets;F. floret (lemma evenly pubescent); G. chromosomes; H. karyotype; I. Lemma epidermal pattern. Scale bar in D represents 2 mm; in E, F represent 5 mm; in G, H represent 5 μm. doi:10.1371/journal.pone.0166603.g001

Fig 3. Illustration of Ptilagrostis contracta. A. habit; B. glume; C. floret; D. palea; E. callus F. outer surface of ligule; G. inner surface of ligule. Scale bar in B, C, F, G represent 5 mm; in D represent 2 mm; in E represent 0.5 mm (Drawn by Z. S. Zhang). doi:10.1371/journal.pone.0166603.g003

Fig 4. Distribution map of Ptilagrostis contracta. doi:10.1371/journal.pone.0166603.g004