Sellaphora tanghongquii, Ni & Guo & Tang & Huang & Kociolek & Li, 2022

Ni, Hong-Ping, Guo, Ji-Shu, Tang, Zheng-Bin, Huang, Ying-Yan, Kociolek, John Patrick & Li, Yan-Ling, 2022, Sellaphora tanghongquii sp. nov. (Bacillariophyta, Sellaphoraceae), a new diatom species from the Southern China, Phytotaxa 573 (1), pp. 103-114 : 106-108

Sellaphora tanghongquii Y.-L. Li sp. nov. ( Figs 2–26 )

Description:— LM ( Figs 2–20 ): Valves broadly linear, margins weakly undulate, slightly constricted near the middle, with round ends. Length 24.5–45.5 μm, width 9.0–11.0 μm, length/width ratio varying between 2.7–4.1, median 3.3 (n = 30). Raphe filiform, lateral and undulate towards the distal and proximal ends. The terminal raphe ends slightly hooked and deflected to the same side. The central raphe ends relatively straight and tipped with slightly inflated pores. Axial area narrow and undulate following the raphe. Central area oval or elliptical, occupying 1/5–1/3 the valve width. Striae radiate more strongly towards the poles, sparser and shorter around the valve center, density 14–17 in 10 µm in the middle portion, up to 22 in 10 µm towards the ends. In some specimens, a longitudinal ridge adjacent to the trough can be seen (see arrow in Figs 3–4 ). Areolae not visible.

SEM: Valves external ( Figs 21–23 ): Raphe undulate with central raphe ends slightly dilated with drop-shaped pores and slightly deflected towards the same side ( Figs 21, 23 ), terminal fissures hooked, deflected towards the opposite side of the valve, terminating onto the mantle ( Figs 21, 22 ). The axial area has shallow troughs on both sides, extending to the apical area and becoming progressively shallower (arrow A in Fig. 21 ), slightly expanded at the apical area ( Figs 21, 22 ), with wavy edges near the middle region ( Fig. 23 ). Striae uniseriate, slightly radiate throughout, and extending onto the mantle ( Figs 21–23 ). Areolae are mostly square and elliptical, partly round, oval, or irregularly shaped along the axial area and central area. Compared with the areolae from the longitudinal ridge to the edge of the mantle (type I: 47–55 in 10 µm), the areolae from the longitudinal ridge to the trough (type II: 42–46 in 10 µm) are smaller (arrow B in Fig. 21 ). Each areola has almost 2–4 small holes internally ( Figs 21–23 ). A row of separated and small pores is present along with the mantle (arrow C in Fig. 21 ). Polar bars are absent.

Valves internal ( Figs 24–26 ): Axial area straight and slightly expanded near the central area. Internal raphe straight, discontinuous with intermission. Central raphe ends not expanded, bending towards the same direction ( Figs 24, 26 ). Terminal raphe ends offset, terminating in elongated and straight helictoglossae ( Figs 24, 25 ). The apical area of the valve has a pore-like pit, and the striae in the apical area are covered by hymenate occlusions ( Fig. 25 ). Striae are biseriate, slightly radiate, formed by round, elliptical, C-shaped, or irregularly shaped areolae (107–150 in 10 µm) delimited by slightly oblique orientated vimines ( Figs 24–26 ).

Type:— CHINA. Guangxi Zhuang Autonomous Region: the Gui River , GR 17, elevation 78 m asl., 24°15′33′′ N, 110°45′51′′ E, Dr. Hong-Qu Tang, 29th July 2021 (Holotype GR202172902! in Coll. Hong-Qu Tang, Jinan University, Guangzhou, China = Fig. 2 ) .

Etymology:— tanghongquii , honors Dr. Hong-Qu Tang, the collector of the type sample.

Figures

FIGURES 2–20. Sellaphora tanghongquii sp. nov., LM, DIC. Valve views, showing size range and variability of the holotype population. In Figs 3–4 the white arrows point to the longitudinal ridges adjacent to the trough. Scale bar = 10 μm.

FIGURES 21–23. Sellaphora tanghongquii sp. nov., SEM, external views. 21. External view of the entire valve. Arrow A in the figure indicates troughs extending to the apical area and progressively becoming shallower. Arrow B indicates areolae becoming smaller from the longitudinal ridge to the trough. Arrow C indicates a row of separated and small pores on the valve mantle. 22. Detail of valve apices showing, uniseriate striae extending into the mantle. 23. External view of valve centre showing central raphe endings with the drop-shaped pores. Scale bar = 1 μm.

FIGURES 24–26. Sellaphora tanghongquii sp. nov., SEM, internal views. 24. Internal view of entire valve. 25. Detail of valve apex, showing pore-like pit and elongated helictoglossae. 26. Detail of the valve central area, showing biseriate striae and central raphe ends bending in the same direction. Scale bar = 2 μm (Figs 24, 26), 1 μm (Fig. 25).