Sellaphora jiuzhaienis Levkov, Plenković-Moraj & Sun, 2023

Sun, Geng, Levkov, Zlatko, Xiao, Weiyang, Moraj, Nikola, Udovič, Marija Gligora, Du, Jie, Chen, Qunlong & Plenković-Moraj, Anđelka, 2023, Sellaphora jiuzhaienis sp. nov. (Bacillariophyceae) - A new diatom species from Jiuzhaigou National Nature Reserve, China, Phytotaxa 626 (4), pp. 259-268 : 261-264

Sellaphora jiuzhaienis Levkov, Plenković-Moraj & Sun sp. nov. (2–39)

Description: LM ( Figs 2–28 ): Valves symmetrical, linear to linear-elliptic with slightly convex valve margins and unprotracted and broadly rounded ends. Valve length 17.5–33.5 μm and 7.0–8.5 μm wide (n=38).Axial area moderately broad, widened towards central area. Central area broad, longitudinally elliptical to round bordered by 4–5 regularly shortened and more distantly spaced central striae. Broad conopeum visible in central area. Raphe linearly arranged within broad conopeum. Ends of central raphe slightly expanded into small central pores, distal raphe fissures long, slightly curved in the same directions and passing onto valve mantle. Striae strongly radiate throughout and slightly curved, 18–20 in 10 μm. Areolae not discernible with LM.

SEM ( Figs 29–39 ): Valve surface flat and transition to valve mantle gradual ( Figs 29, 31 ). Raphe situated on very wide conopeum surrounded on both sides by deep and narrow grooves ( Figs 29–34 , white arrows in Figs 33, 34 ). Conopeum very broad in central area and occupies half of valve width ( Figs 32, 34 ). Raphe linear with slightly expanded central pores and slightly unilaterally deflected ( Figs 32, 34 ). Distal raphe ends long, curved unilaterally towards secondary valve side and passing onto valve mantle ( Fig. 33 ). Polar bars absent ( Fig. 33 ). Internally, the raphe is linear with indistinct central ends located in a slightly elevated central area ( Figs 35, 37 ). Distally, the raphe terminates in small helictoglossae ( Figs 36, 38, 39 ). Large foramen-like (pit), which does not penetrate externally, present distally of the helictoglossae ( Figs 36, 38, 39 ). Striae uniseriate, composed of small, round areolae ( Figs 35–39 ). Areolae about 60 in 10 μm, towards apices and valve margin becoming smaller. Striae separated by thickened interstriae ( Figs 37, 39 ). Internally, areolae occluded by dome-shaped hymens (white arrow in Fig. 38 ). In corroded specimens’ areolae appear as open holes ( Figs 36, 37, 39 ).

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 dates: 29.04.201 5, Slide HRNDC 48 J2016 (holotype) , slide MKNDC! 14382/A (isotype)

Etymology: the specific epithet ( “ jiuzhaienis ”) refers to the name of the Jiuzhaigou Nature Reserve from where this species is described.

Ecology: This new species occurred at 5.5 % 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) (18.6%), Cymbella hantzschiana Krammer (2002: 62) (16.2%), Tryblionella angustata W. Smith (1853: 36) (15.3%), Nitzschia fossilis (Grunow in Cleve & Grunow 1880: 98) Grunow (in Van Heurck 1881, fig. 68: 24) (10.2%), and Gomphonema acuminatum Ehrenberg (1832: 88) (6.2%). The 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: Thus far, the new species was observed only at the type locality Mirror Lake in Jiuzhai Valley.

Figures

FIGURES 2–28. Sellaphora jiuzhaienis sp. nov. Light microscopy (LM). Valve size diminution series. Scale bar = 10 μm.

FIGURES 29–34. Sellaphora jiuzhaienis sp. nov. Scanning electron microscopy (SEM). Figs 29–31. External view of entire valve. Figs 32, 33. External view of half of the valve. White arrow indicates narrow grooves surrounding the conopeum. Fig. 34. Detailed external view of the valve centre (white arrow indicates narrow grooves surrounding the conopeum). Scale bar = 5 μm (29–31), 2 μm (32–34).

FIGURES 35–39. Sellaphora jiuzhaienis sp. nov. Scanning electron microscopy (SEM). Fig. 35. Internal view of entire valve. Figs 36, 39. Internal view of half of the valve. Fig. 37. Detailed internal view of the valve centre. Fig. 38. Internal view of valve apex (white arrow indicates dome-shaped hymens), Scale bar = 5 μm (35), 2 μm (36–39).