Stauroneis saprophila M. Rybak, Noga & Ector, 2017

Noga, Teresa, Rybak, Mateusz & Ector, Luc, 2017, Description of Stauroneis saprophila sp. nov. (Bacillariophyta), a new diatom species from anthropogenic environment, Phytotaxa 327 (3), pp. 269-275 : 270-273

Stauroneis saprophila M. Rybak, Noga & Ector , sp. nov. ( Figs 3–25 )

Valves linear-lanceolate with rostrate ends ( Figs 3–17 ). Observed range of valve dimensions (n = 40): length 29.3– 50.8 μm, width 7.9–11.4 μm. Striae radiate throughout the entire valve, 13–16 in 10 μm ( Figs 3–20 ). Puncta clearly visible in LM, 21–23 in 10 μm ( Table 1). Under SEM areolae usually rounded, sometimes slightly elongated. Puncta decreasing in size towards the valve margin ( Figs 22–24 ). Raphe filiform, almost straight. The proximal raphe ends are rounded to tear-drop shaped ( Fig. 23 ). Distal raphe ends hooked toward the valve margin ( Fig. 24 ). Axial area narrow, central area is typical in stauros shape, without striae ( Figs 19, 20, 23 ). One row of pores is present on the girdle bands ( Fig. 22 ). In internal valve view areolae bacilliform, often with hyaline band. Pseudoseptum is present, hiding the distal raphe ends ( Figs 21, 25 ).

Type:— POLAND. Podkarpacie Province, Stalowa Wola , coordinates: 50º34’17.67”N, 22º04’33.78”E, M. Rybak, 12 November 2016, holotype slide BR-4473, deposited in Botanic Garden Meise (Belgium), illustrated in Fig. 7 ; isotype: slide PIRCE 2016 /8 deposited in University of Rzeszów (Poland) .

Etymology:— The species name saprophila refers to the environmental conditions in which it was found; all dominant diatom species are α- meso-/polysaprobous or polysaprobous ( Van Dam et al. 1994).

Distribution and ecology:— Stauroneis saprophila occurred from March to November 2016 in each sample, always individually, with a slight increase in November (up to approximately 0.5%). The sampling site was highly insolated. The water temperature was close to the air temperature and changed seasonally. The pH of the water was alkaline to strongly alkaline (in summer to 9.8), and the conductivity was high to very high – the highest in November (13 250 μS cm-1) when water was not flowing. In March and June the studied water contained high levels of nutrients, especially nitrates. Values of other ions (mainly chloride and sodium) were the highest in November, when the water was not flowing, and the diatom material was collected only from a pool ( Table 2).

Together with Stauroneis saprophila (0.1–0.5%), the most frequent species in the assemblages were Nitzschia palea ( Kützing 1844: 63) W. Smith (1856: 89) (45–74%), Fistulifera saprophila ( Lange-Bertalot & Bonik 1976: 312) Lange-Bertalot (1997: 73) (6–24%), Gomphonema saprophilum (Lange-Bertalot & E. Reichardt in Lange-Bertalot 1993: 69–70) N. Abarca, R. Jahn, J. Zimmermann & Enke (2014: 11) (5–12%) and Craticula minusculoides ( Hustedt 1942: 68) Lange-Bertalot (2001: 115) (5–10%).

Temperature [ºC] 6.2–30.6 PO 4 3- [mg l-1] ˂0.001–3.3

pH 7.9–9.8 NH

4

+ [mg l-1] ˂0.001–0.5

Conductivity [μS cm-1] 331–13 250 Na + [mg l-1] 38.3–2 689.2

Cl- [mg l-1] 51.7–4 455.5 K + [mg l-1] 18.1–66.7

SO 4 2- [mg l-1] 21.4–75.7 Mg 2+ [mg l-1] 4.8–38.4

NO 3 - [mg l-1] ˂0.001–37.7 Ca 2+ [mg l-1] 32.4–145.9

Figures

FIGURES 3–17. LM images of Stauroneis saprophila. Scale bar = 10 μm.

FIGURES 18–25. SEM images of Stauroneis saprophila. 18–20 External view of an entire valve. 21. Internal valve view of entire valve. 22. External view of valve apex, with visible girdle band perforations. 23. External view of central area. 24. External view of valve apex with distal raphe end. 25. Internal view of valve apex with clearly visible pseudoseptum. Scale bars: Figs 18–21, 25 = 10 μm, Figs 22–24 = 5 μm.