Diploneis zhui Levkov, Plenković-Moraj & Sun, 2023

Sun, Geng, Levkov, Zlatko, Xiao, Weiyang, Moraj, Nikola, Udovič, Marija Gligora, Du, Jie, Chen, Qunlong & Plenković-Moraj, Anđelka, 2023, New diatom species Diploneis zhui sp. nov. from Jiuzhaigou National Nature Reserve, China, Phytotaxa 629 (3), pp. 235-244 : 237-240

Diploneis zhui Levkov, Plenković-Moraj & Sun sp. nov. (LM 2–25, SEM 26–35)

Description: LM ( Figs 2–25 ): Valves linear to linear-elliptic with broadly rounded ends. Length 18–39 μm, breadth 9.5–11.0 μm. Axial area narrow, linear, central area small, longitudinally elliptical to round. Raphe filiform, with slightly expanded central pores. Longitudinal canals present on both sides of raphe, linear, opened with two small areolae. Striae almost parallel at mid-valve to strongly radiate towards valve apices, 16–18 in 10 μm. Areolae fine, visible with LM, ca. 25 in 10 μm.

SEM ( Figs 26–35 ): Valve face is flat and transition to the valve mantle is gradual ( Figs 26, 27 ). Central area is slightly raised ( Figs 28, 30 ). Raphe is linear with unilaterally deflected proximal raphe ends ( Figs 28, 30 ). Distal raphe ends short and unilaterally bent, not passing on valve mantle ( Figs 26, 29 ). Raphe is not surrounded with raphe ribs ( Fig. 28, 30 ). Externally, axial area very narrow, linear bordered by longitudinal canal ( Figs 26, 27 ). Longitudinal canal is linear with two rows of areolae occluded by cribra ( Figs 29, 30 ). Striae uniseriate near raphe becoming biseriate towards valve margin ( Figs 26, 30 ). Biseriate pattern of striae at marginal part visible internally in corroded specimens ( Figs 33, 34 ). Internally, raphe is linear with simple proximal and distal raphe ends ( Figs 33–35 ), placed in depression formed by longitudinal canal ( Figs 31–35 ). Internally, axial area broad covered by silica plate that encloses longitudinal canal ( Figs 31–35 ). Striae covered with thin silica layer ( Fig. 35 ).

Type:— CHINA: Jiuzhaigou National Nature Reserve , Mirror Lake, rocks from 0.5 to 1 m deep on the east coast, coordinates 103°53′57.80” E, 33°9′34.90” N (Accession No. 42); Leg. N. Moraj & W. Xiao; collection date: 29.04.201 5, Slide HRNDC! 48J2016 (holotype), Fig. 7 represents the holotype specimen ; slide MKNDC! 14382/B (isotype)

Etymology:—The species is named in honor of Zhongfu Zhu, a researcher, scientist and irreplaceable colleague of Jiuzhaigou Administrative Office, Sichuan, China, who sadly passed away.

Ecology:— Diploneis zhui occurred at 5,0 % relative abundance (total counted, 400 valves) in samples together with species that accounted for more than 5 %: Navicula cryptotenella Lange-Bertalot (in Krammer & Lange-Bertalot 1985: 62) (18.5%), Cymbella hantzschiana Krammer (2002: 47) (16.0%), Tryblionella angustata W. Smith (1853: 36) (15.0%), Nitzschia fossilis (Grunow) Grunow (in Van Heurck 1881, fig. 68: 24) (10.0%), Gomphonema acuminatum Ehrenberg (1832: 88) (6.0%) and Sellaphora Mereschkowsky (1902: 186) sp. (5.5%). Mean values of environmental parameters were: pH = 8.22, water temperature = 9.72 °C, conductivity = 351 μs/cm, Total N = 417 μg/L and Total P = 8 μg/L.

Distribution:—So far, the new species was observed only at the type locality Mirror Lake in Jiuzhai Valley.

Figures

FIGURES 2–25. Diploneis zhui sp. nov. Light microscopy. Valve size diminution series. Scale bar = 10 μm.

FIGURES 26–30. Diploneis zhui sp. nov. Scanning electron microscopy. Figs 26, 27. External view of the entire valve. Figs 28, 30. External view of the middle of the valve. Fig. 29. Detailed external view of the valve end. Scale bar = 5 μm (26, 27), 2 μm (28–30).

FIGURES 31–35. Diploneis zhui sp. nov. Scanning electron microscopy. Figs 31, 32. Internal view of the entire valve. Figs 33. Internal view of half of the valve. Fig. 34. Detailed internal view of the valve end. Fig. 35. Detailed internal view of the valve centre. Scale bar = 5 μm (31, 32), 2 μm (33–35).