Prestauroneis dayaensis W. Zhang & Kociolek, 2024

Species Prestauroneis dayaensis W. Zhang & Kociolek sp. nov.

(LM: Figs 2–7 View FIGURES 2–7 , SEM: Figs 8–19 View FIGURES 8–12 View FIGURES 13–19 )

Description

LM ( Figs 2–7 View FIGURES 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 View FIGURES 8–12 View FIGURES 13–19 ). Externally ( Figs 8–12 View FIGURES 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 View FIGURES 8–12 ). The axial area linear. Sternum slightly elevated ( Figs 8, 12 View FIGURES 8–12 ). Stauroid fascia narrow, rectangular, slightly elevated, some of them with a shortened striae at one side ( Fig. 12 View FIGURES 8–12 ). 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 View FIGURES 8–12 ). Striae spaced with robust interstriae ( Figs 8, 12 View FIGURES 8–12 ).

Internally ( Figs 13–19 View FIGURES 13–19 ), sternum and stauroid fascia elevated ( Figs 13, 16, 19 View FIGURES 13–19 ). A short distinct pseudoseptum present at each end ( Figs 13–15 View FIGURES 13–19 ). Areolae openings rounded, completely covered by hymens ( Fig 18 View FIGURES 13–19 ). Proximal raphe endings slightly dilated, slightly curved to one side ( Figs 16, 17, 19 View FIGURES 13–19 ).

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 View FIGURES 2–7 . GoogleMaps 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.

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) .