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Three new species of Ulnaria (Kützing) Compère (Bacillariophyta) from China, with reference to the fine structure of their valvocopula

Bing LIU, David M. WILLIAMS, Saúl BLANCO, Zhu-Xiang LIU & Dan LIU

en Cryptogamie, Algologie 40 (11) - Pages 119-139

Published on 11 December 2019

Three new species of Ulnaria (Kützing) Compère are described based on light and scanning electric microscopy observations. Ulnaria oxybiseriata D.M. Williams & Bing Liu, sp. nov., has linear-lanceolate to lanceolate valves with apiculate and produced ends, biseriate striae, and a central area mostly forming an incomplete fascia surrounded by shortened striae on one side. Ulnaria jinbianensis S. Blanco & Bing Liu, sp. nov., bears linear-lanceolate valves with rostrate to subrostrate ends in larger valves and cuneate ends in smaller valves, uniseriate stria, and a central area forming a rectangular to trapezoid fascia. Ulnaria dongtingensis Bing Liu, sp. nov., possesses a narrow-lanceolate valve outline with produced rostrate to capitate ends, uniseriate stria, and a central area forming almost square fascia. The valvocopula of all three new species bears the same ultrastructure: 1) a complete valvocopula is a closed ring with the same shape as the valve outline, closely attached to the mantle interior surrounding the valve margin; 2) each valvocopula present a row of poroids which bisects the pars interior and exterior; 3) valvocopula with sawtooth-shaped projections attached to the valve over virgae internally; and 4) the valvocopula closed and hyaline at both apices. All three species were found in alkaline freshwater (around pH 8) with moderate conductivity (c. 102-221 μS/cm).


Keywords :

Closing plate, dongting Lake, fascia, silica sawtooth, Wuling Mountains, new species

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