Pinnularia dongzhenensis W.Zhang, S.C.Yin & Kociolek, 2022

Zhang, Wei, Yang, Han, Wang, Ni, Cai, Mei, Kociolek, John Patrick & Yin, Sicheng, 2022, Pinnularia dongzhenensis sp. nov., a new freshwater diatom species (Bacillariophyceae) from Dongzhen Reservoir, Fujian Province, China, Phytotaxa 548 (1), pp. 82-90 : 83-84

Species Pinnularia dongzhenensis W.Zhang, S.C.Yin & Kociolek , sp. nov. (LM: Figs 1–7 , SEM: Figs 8–23 )

Valves narrowly linear-lanceolate, with slightly undulate margins, slightly constricted center and subcapitate apices ( Figs 1–9 ). Valve length 36–48 µm (average 42.2 µm), breadth 5.4–7.0 µm (average 6.2 µm), length-to-breadth ratio 6.0–7.9 (average 7.0) (n = 62). Axial area narrow, 1/5–1/3 of the valve breadth, linear, widening towards the central area ( Figs 1–9 ). Central area present, generally forming an asymmetric, rhombic fascia ( Figs 1–9 ). Raphe lateral with outer fissures weakly curved. Proximal raphe ends weakly expanded, funnel shaped and deflected in the same direction ( Figs 1–11 ). Terminal raphe fissures curved towards secondary side of valves strongly sickle-like, approximately hooked ( Figs 14–15 ). Striae 10–12 in 10 µm (n=62), radiate in the middle, slightly convergent towards the ends ( Figs 1–9 ). Alveoli pattern with 5–6 rows of rounded areolae, each row with 11–13 areolae in 2 μm ( Figs 12–15 , 20–23 ). Internally, the central nodule is present and bulging. The intermissio and internal raphe are covered by flap extended from the central nodule ( Figs 16–19 ). The distal raphe endings terminate in prominent helictoglossae, located 0.8–1.6 μm from apices ( Figs 22–23 ).

Type locality:— CHINA, Fujian Province: Putian City, Dongzhen Reservoir , 25°28′21″ N, 118°56′43″ E, elevation 65 m asl., Dr. Wei Zhang, 22th January 2021 (holotype Dongzhen1#, SHOU! Herbarium of the Hydrobiological Department, Shanghai Ocean University, Shangai, China = Fig. 4 ) .

Etymology:— The specific epithet ‘ dongzhenensis ’ refers to the locality from which the new species is described.

Ecology:— Pinnularia dongzhenensis sp. nov. occurs in surface sediments of a deep reservoir. At the time of collection, the water column was eutrophic (TN 0.80–1.05 mg ·L- 1, TP 0.04–0.08 mg ·L- 1), had low conductivity (50–70 µs· cm-1), high dissolved oxygen (11.24–11.50 mg ·L- 1), neutral pH (6.95–7.26) and the water temperature was 15.4 °C. The concentrations of nutrients of the sediments were high (TN 1.01–2.85 g · kg-1, TP 0.37–0.66 g · kg-1, organic matter 17.78–23.75 g · kg-1).

Figures

FIGURES 1–7. LM micrographs of the type population of Pinnularia dongzhenensis from Dongzhen Reservoir. Scale bar = 10 μm.

FIGURES 8–15. Pinnularia dongzhenensis sp. nov., SEM external views of P. dongzhenensis sp. nov.. 8, 9. General view of valve. 10, 11. Central area showing proximal raphe fissures bent in the same direction. 12, 13. Details of alveoli with rows of rounded areolae. 14, 15. Detail of the sickle–shaped raphe fissure at pole, and each alveolus with rows of rounded areolae. Scale bars = 10 μm (Figs 8, 9), 2 μm (Figs 10–15).

FIGURES 16–23. Pinnularia dongzhenensis sp. nov., SEM internal views of P. dongzhenensis sp. nov.. 16, 17. Entire valve. 18, 19. Central area; an intermissio is apparently lacking. 20, 21. View showing alveoli pattern. 22, 23. Valve apex showing typical helictoglossa. Scale bars = 10 μm (Figs 13, 17), 2 μm (Figs 18–23).