Stauroneis schinzii var. maxima Frenguelli 1933

Vouilloud, A. A., Guerrero, J. M., Palladino, M. B. & Lamaro, A. A., 2021, Revision Of The Type Materials Of Stauroneis Schinzii Var. Argentina Frenguelli And S. Schinzii Var. Maxima Frenguelli (Bacillariophyceae), Phytotaxa 478 (1), pp. 119-130 : 124-126

Stauroneis schinzii var. maxima Frenguelli 1933 (385, Pl. 1, fig. 11) ( Figs 22–31 )

Original description (as Stauroneis schinzi var. maxima ): Fig. 22

Puede considerarse como una forma ligada a la variedad anterior [ var. argentina ]; pero de dimensiones mucho mayores, de sílice más robusta, con extremos valvares menos atenuados, redondeados y con menor número de estrías. Valva: largo 0,294 a 0,308 ancho 0,026 a 0,027; estrías 11 en 0,01.

Here translated: “It can be considered a form linked to the previous variety [ var. argentina ], but with much higher valve dimensions, more heavily silicified, with less attenuated valve ends and lower stria number. Valve: length 0.294 a 0.308 [mm], width 0.026 a 0.027 [mm]; striae 11 in 0.01 [mm]”.

Frenguelli recorded S. schinzii var. maxima as rare in Series 268. Our LM examination of the slides recovered 11 broken specimens of this variety. During SEM examination of Series 268 we found only one broken valve in internal view.

Figures

FIGURES 22–31. Stauroneis schinzii var. maxima Frenguelli. Figs 22. Original drawing of Frenguelli (1933, Pl. I, fig. 11). Figs. 23–28. LM. Specimens from type population. Fig. 24. Lectotype. Fig. 27. Detail of valve end showing distal raphe fissure. Note the thickened sternum. Fig. 28. Detail of valve centre showing sternum and proximal raphe ends. Figs 29–31. Specimen from type population. SEM. Fig. 29. Detail of internal valve end showing distal raphe end terminating in a weakly developed helictoglossa (arrow). Fig. 30. Detail of internal valve center showing proximal raphe ends and stauros. Fig. 31. Broken tilted valve in internal view. Scale bars: 10 µm (Figs 22–26, 31); 5 µm (Figs 27–30).