Prestauroneis dayaensis W. Zhang & Kociolek 2024, sp. nov.

Species Prestauroneis dayaensis W. Zhang & Kociolek sp. nov. (LM: Figs 2–7, SEM: Figs 8–19) Description LM (Figs 2–7). Valves elliptic to lanceolate-elliptical with distinctive rostrate to subcapitate ends and slightly convex margins, length 25.5–32.0 μm, width 8.0–11.5 μm (n=24). L/W ratio 3.11. Axial area narrow, linear. Central area forming a narrow stauroid fascia, rectangular, some of them with one shortened stria on one side. Raphe straight, the proximal raphe ends slightly enlarged, toward to the same side. Striae relatively widely-spaced and radiate at the center part, nearly parallel at the ends, 18–20 in 10 μm. Distinct pseudosepta present at both ends. SEM (Figs 8–19). Externally (Figs 8–12), central raphe endings slightly expanded and weakly curved to the same side, terminal raphe fissures hook-shaped, curved in the opposite direction relative to the central raphe ends, extending to the mantle (Figs 9–12). The axial area linear. Sternum slightly elevated (Figs 8, 12). Stauroid fascia narrow, rectangular, slightly elevated, some of them with a shortened striae at one side (Fig. 12). Openings of areolae variable in shape, circular at the central area, linear to elliptic at the ends, 37–40 in 10 μm. (Figs 8–12). Striae spaced with robust interstriae (Figs 8, 12). Internally (Figs 13–19), sternum and stauroid fascia elevated (Figs 13, 16, 19). A short distinct pseudoseptum present at each end (Figs 13–15). Areolae openings rounded, completely covered by hymens (Fig 18). Proximal raphe endings slightly dilated, slightly curved to one side (Figs 16, 17, 19). Type locality:— CHINA, Guangdong Province: Huizhou City, Daya Bay area, Danao River 22°74'N, 114°51'E, elevation 88 m a.s.l., Dr. Wei Zhang, 16 December 2023 (holotype Huizhou20231201, SHOU! Herbarium of the Hydrobiological Department, Shanghai Ocean University, Shanghai, China = Fig. 6. Isotype Huizhou20231203, Jiangnan University, Wuxi, China.) Etymology:—The specific epithet ‘ dayaensis’ refers to the locality from which the new species was found. Ecology:— Prestauroneis dayaensis sp. nov. was found at two sites from the Danao River (22°73'N–22°78'N, 114°48'E – 114°54'E), the water temperature was 19.70–21.72 ℃, pH 7.55–8.29, conductivity 570–610 μs· cm-1. ......continued on the next page Associated taxa:—The dominant algal species in the collection site were as follows Nitzschia clausii Hantzsch (1860: 40), Sellaphora pupula (Kützing) Mereschkowsky (1902: 187), Nitzschia filiformis (W. Smith) Van Heurck (1896: 406), Nephrococcus confertus Y.-Y. Li (1984: 191), Stylosphaeridium stipitatum (H. Bachmann) H. Bachmann in Geitler & Gimesi (1925: 609), Phormidium mucicola f. roseum Skuja (1956: 66), and Lyngbya kuetzingii Schmidle (1897: 58), as well as, some other unidentified diatom species of the genera Nitzschia Hassall (1845), and Navicula Bory (1822).