Psammoneis fujianensis, Qiu & Liu & Gao & Liang & Sun & Chen, 2025, Qiu & Liu & Gao & Liang & Sun & Chen, 2025

Qiu, Yu, Liu, Honghan, Gao, Yahui, Liang, Junrong, Sun, Lin & Chen, Changping, 2025, Psammoneis fujianensis sp. nov. (Bacillariophyceae), A New Epipsammic Diatom Species from Fujian, China, Phytotaxa 704 (1), pp. 79-86 : 81

Description

LM: Observations of living cells indicate that each cell contains two plastids. Rectangular cells are interconnected via one or both sides of the valve face, forming zigzag or straight-chain colonies ( Figs 1I, J ). Valve length ranges from 7.8 to 9.2 μm and width ranges from 2.6 to 3.9 μm. LM reveals that valve outline is linear-elliptical, with the broad and lanceolate central area. Striae are clearly visible, oriented-perpendicular to the sternum, with 19-22 in 10 μm, while the areolae in apical pore fields at both ends are not visible (Figs A–H).

SEM : The valve outline is linear-elliptical with rounded ends ( Fig. 2A ). The valve is flat, lacking marginal spines, and curves to form a deep mantle ( Figs 3C, 3D , 4 , 5 ). Valves exhibit a distinct and narrow sternum with striae oriented-perpendicular thereupon ( Fig. 2A ). Striae are arranged in parallel, with 19-22 in 10 μm. Areolae are narrow linear to elliptical, with densities ranging from 111-121 in 10 μm, and C-shaped areolae near the sternum ( Fig. 2C ). Apical pore fields are located at both ends of the valve, with areolae extending from the valve face to the mantle face, appearing irregularly round or square and diverging towards the mantle ( Figs 2B , 3B ). The girdle bands are smooth, unperforated and numerous. However, the girdle bands treated with acidization are easy to fall off ( Fig. 3C ), while those treated with critical point drying are completely preserved ( Figs 4 , 5 ). SEM of critical point drying shows that cells secrete gelatinous material via apical pore fields, connecting adjacent cells to form zigzag or straight-chain colonies ( Fig. 4 ); some cells secrete gelatinous material via apical pore fields to form gelatinous stalks ( Fig. 5 ).

Type. CHINA. Fujian Province, Quanzhou City: Sandy beach of Weitou Bay , 118°34’49”E, 24°31’07”N, 19. June. 2022, Collector Honghan Liu.

Holotype (designated here). Slide DL202302, deposited in the School of Life Sciences, Xiamen University, Xiamen, People’s Republic of China . Holotype specimen is illustrated in Fig. 1E .

Distribution. The taxon is first known from the type locality, followed by its appearance on the sandy beach of Maluan Bay, Dongshan County, Fujian Province, China, on November 3, 2023.

Etymology. The epithet “ fujianensis ” derives from the site where the specimen was found twice.

Figures

FIGURE 1. LM of P. fujianensis sp. nov. Figs A–H. From cleaned frustules; Figs I, J. From living cells; Fig. J. Cells containing two plastids (arrows). Scale bars: 2 μm (A–H); 10 μm (I, J).

FIGURE 2. SEM of P. fujianensis sp. nov. Fig. A. External view of the valve. Fig. B. Apical pore fields of the external valve. Fig. C. External valve view showing C-shaped areolae near the sternum (triangles). Scale bars: 1 μm.

FIGURE 3. SEM of P. fujianensis sp. nov. Fig.A. Internal view of the valve. Fig. B. Apical pore fields of the internal valve. Fig. C. Girdle view of the valve with several girdle bands. Fig D. Girdle view of the valve of two connected cells. Scale bars: 1 μm.

FIGURE 4. SEM of critical point dried P. fujianensis sp. nov. Fig. A. Cells connecting to each other in chains; Fig. B. Cells connecting to adjacent cells by gelatinous material secreted via apical pore fields (arrow); girdle view of the valve with numerous girdle bands; valve curving to form a deep mantle. Scale bars: 2 μm.

FIGURE 5. SEM of critical point dried P. fujianensis sp. nov. Fig. A. An individual cell secreting gelatinous stalk via apical pore fields (arrow). Fig. B. Two adjacent cells secreting gelatinous material via apical pore fields to form a shared gelatinous stalk (arrow). Scale bars: 2 μm.