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)