Cymbella pamirensis sp. nov. (Bacillariophyceae) from an alpine lake in the Pamir Mountains, Northwestern China Author Zhang, Zhongyan Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China & University of Chinese Academy of Sciences, Beijing 100049, China Author Rioual, Patrick Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China prioual@mail.igcas.ac.cn Author Peng, Yumei University of Chinese Academy of Sciences, Beijing 100049, China & State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075, China Author Yang, Xiaoping School of Earth Sciences, Zhejiang University, Hangzhou 310027, China Author Jin, Zhangdong State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075, China & Institute of Global Environmental Change, Xi’an Jiaotong University, Xi’an 710049, China Author Ector, Luc Luxembourg Institute of Science and Technology, Department of Environmental Research and Innovation, 41 rue du Brill, L- 4422 Belvaux, Luxembourg text Phytotaxa 2017 2017-06-07 308 2 249 258 http://dx.doi.org/10.11646/phytotaxa.308.2.6 journal article 302387 10.11646/phytotaxa.308.2.6 211fb518-264c-48af-8c7c-b1890abe6d17 1179-3163 13701843 Cymbella pamirensis Z.Zhang & Rioual , sp. nov. ( Figs 2–34 ) LM observations ( Figs 2–28 ) Valves strongly dorsiventral and triangular. Dorsal margin strongly arched. Ventral side nearly straight or slightly concave with slightly tumid center part. Ends variable from broadly round to weakly protracted. Valve dimensions (n=48): length 21 – 39 μm, width 7 – 10.5 μm, length/width ratio 2.6 – 4.3 (median 3.3), curvature value 0.038 – 0.083 . Axial area linear, narrow, widening slightly at mid-valve on the dorsal side, almost in the middle of the valve. Central area generally lacking on the ventral side or very small ( Figs 27, 28 ), but present dorsally where striae gradually shortened. Raphe branches lateral, becoming narrower near distal ends ; terminal fissures curved dorsally. Striae moderately radiate in middle of valve. No isolated stigmata discernible under the LM.