Ptilagrostis contracta (Stipeae, Poaceae), a New Species Endemic to Qinghai-Tibet Plateau

PLOS ONE, Dec 2019

A new species, Ptilagrostis contracta, endemic to Qinghai-Tibet Plateau is described and illustrated. It is distinguished from other species in Ptilagrostis by having contracted panicles, 1-geniculate awns with hairy columns and scabrous bristles and evenly pubescent lemmas. Evidence from lemma epidermal pattern, cytology and molecular phylogenetic analyses based on the nuclear ITS sequence data confirm its systematic position in Ptilagrostis.

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Ptilagrostis contracta (Stipeae, Poaceae), a New Species Endemic to Qinghai-Tibet Plateau

January Ptilagrostis contracta (Stipeae, Poaceae), a New Species Endemic to Qinghai-Tibet Plateau Zhong-Shuai Zhang 0 1 Ling-Lu Li 0 1 Wen-Li Chen 0 1 0 State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences , Beijing , China , 2 University of Chinese Academy of Sciences , Beijing , China 1 Editor: Fan Chen, Institute of Genetics and Developmental Biology Chinese Academy of Sciences , CHINA A new species, Ptilagrostis contracta, endemic to Qinghai-Tibet Plateau is described and illustrated. It is distinguished from other species in Ptilagrostis by having contracted panicles, 1-geniculate awns with hairy columns and scabrous bristles and evenly pubescent lemmas. Evidence from lemma epidermal pattern, cytology and molecular phylogenetic analyses based on the nuclear ITS sequence data confirm its systematic position in Ptilagrostis. Introduction Ptilagrostis Griseb. is a small genus of approximately 11 high altitude species, widely accepted on the basis of its distinctive morphological characters, cytological evidence [1±6] and molecular data [ 7, 8 ]. Ptilagrostis is disjunctive in Asia and North America [5, 9±12] with the diversity center in the Qinghai-Tibet Plateau, where approximately eight taxa occur. They grow in various alpine habitats, including meadows, grasslands, shrubby and even Abies forests. During several botanical expeditions to Sichuan Province in 2013±2015, some unusual populations of Ptilagrostis were discovered in Litang and Kangding counties, located in the southeastern Qinghai-Tibet Plateau. The plants can be distinguished from all the other known Ptilagrostis species by having contracted panicles, 1-geniculate awns with pubescent columns and scabrid bristles and evenly pubescent lemmas. We determined that these populations represent a hitherto undescribed species and named as P. contracta. It is strongly supported to be a member within Ptilagrostis by the evidence from lemma epidermal pattern, cytology and molecular phylogenetic analyses based on the nuclear ITS sequence data. The detailed description of the new species is given below. Material and Methods Ethics statements All the collecting locations of the new species reported in this study are not in any natural conservation area and no specific permissions were required for these locations. And our field studies did not involve any endangered or protected species. (grant no. 2013FY112100), http://most.gov.cn/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of the authors are articulated in the 'author contributions' section. Competing Interests: The authors have declared that no competing interests exist. Material collection A total of five populations of new species were collected and examined during the field work conducted in the Qinghai-Tibet Plateau from 2013 to 2015. The specimens from PE, HNWP, KUN, CDBI were carefully checked, as well as the specimens borrowed from HITBC, B, CAS, GOET and K. Chromosome preparations Matured caryopses and voucher specimen were collected by the authors during the field trip in Litang. Voucher specimen: CHINA. Sichuan, Litang, Long. 100.41842 E, Lat. 29.72025 N, 3701 m, 26 September 2014, Z. S. Zhang & L. L. Li 341, deposited in the Herbarium, Institute of Botany, CAS (PE). Vigorous root tips obtained from germinated caryopses were pre-treated in an ice water mixture at 0Ê for 24 hours, then fixed in Carnoy's fluid (3: 1 ethanol: glacial acetic acid) at 4Ê for at least 30 min. They were then digested at 37Ê in a combination (1:1) of 2.5% cellulase and 1.25% pectinase for 1 hour before being stained with improved carbol-fuchsin solution [ 13 ] and squashed for cytological observation. Permanent slides were made using the standard liquid nitrogen method. The photographs were taken using a Zeiss Axio Imager A1 camera. The karyotype was analyzed following Li and Chen [ 14 ]. Lemma epidermal pattern Lemma ultra structure was studied by using dry mature caryopses sampled from the type specimen. To remove epicuticular wax the lemmas were cleaned in xylene for an hour. Samples were mounted and then covered with gold from a vacuum spray gun (type S-800, HITACHI). All the observation and photographs were made at varying magnifications by using scanning electron microscope (Hitachi S-4800 FESEM, Hitachi, Tokyo, Japan). Molecular systematics Taxon sampling. In order to determine the systematic position of the new species, one new ITS sequence, for Ptilagrostis contracta, was added to a data alignment of 48 selected accessions from GenBank of Ptilagrostis species and selected species of 23 other Stipeae genera, with Phaenosperma globosum Munro ex Benth. as an outgroup [ 7, 8 ]. GenBank accession numbers and voucher information for the materials used in this study are provided in S1 Table. DNA extraction, amplification and sequenc (...truncated)


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Zhong-Shuai Zhang, Ling-Lu Li, Wen-Li Chen. Ptilagrostis contracta (Stipeae, Poaceae), a New Species Endemic to Qinghai-Tibet Plateau, PLOS ONE, 2017, Volume 12, Issue 1, DOI: 10.1371/journal.pone.0166603