Discostella taxa (Bacillariophyta) from the Río Limay basin (northwestern Patagonia, Argentina)

Figures & data

Table 1 . Collecting dates and sites for samples examined in this study. LP(C) refers to the Herbarium of the Departamento Cientifíco Ficología, Facultad de Ciencias Naturales y Museo de La Plata

Sample number	Date	Site
LP(C) 3313	August 1981	Río Collon Cura
LP(C) 3319	January 1981	Río Limay (headwaters)
LP(C) 3321	January 1982	Río Alumine
LP(C) 3333	September 1995	Arroyito Reservoir
LP(C) 3337	October 1994	Piedra del Aguila Reservoir (near dam)
LP(C) 3339	April 1996	Piedra del Aguila Reservoir
LP(C) 3341	August 1981	Lago Nahuel Huapi
LP(C) 3342	August 1981	Río Limay (downstream Arroyo Carbón)
LP(C) 3343	August 1981	Río Traful
LP(C) 3352	August 1981	Río Limay (headwaters)
LP(C) 4502	June 1981	Río Chimehuin
LP(C) 4518	August 1981	Río Limay (at Estancia La Picasa)
LP(C) 4519	October 1997	Alicura Reservoir
LP(C) 4520	April 1996	Piedra del Aguila Reservoir (near dam)

Table 2 . Comparative morphological features of the Discostella taxa from the Río Limay basin (Argentina)

	Diameter (µm)	Striae/10 µm	Areolae/10 µm	External fulto- portula opening	Striae/fultoportulae	Frustule heterovalvar	Valve mantle
D. stelligera var. stelligera	7.5–20	9–12	28–36	With slightly raised rim	2	+	Scarcely developed
D. stelligera var. elliptica ^a	11–20 × 9–15.5 (14.5–23 × 12–20)	10–14 (10–15)	40–50 (45–50)	With slightly raised rim	1–2	–	Scarcely developed
D. glomerata	4–11.5	12–16 (20)	60	Shortly tubular	(1) 2–3	+	Scarcely developed
D. pseudostelligera	5–8	20–24 (28)	55–80	Tubular forked	4–7	+	Developed
D. woltereckii	6.5–7.5	20–22	70–80	Tubular forked	6–7	?	Developed
Discostella sp. 1	20–27.5	9–12	25–30	With slightly raised rim to shortly tubular	1–2	?	Developed
Discostella sp. 2	10.5–18	11–15	50–60	Complex	1–2	+	Developed
^aFigures in brackets correspond to Frenguelli's material.

Figs 1–8. Discostella stelligera var. stelligera. Figs 1, 2. Light micrographs. Fig. 1. Valve view of a valve with convex central area. Fig. 2. Valve view of a valve with concave central area. Figs 3–8. Scanning electron micrographs. Fig. 3. External view of a valve with a convex central area. Fig. 4. External view of a valve with a concave central area. Note irregularly scattered pores in the central area (arrowhead). Fig. 5. Frustule in girdle view. Arrowheads indicate the external openings of the fultoportulae. Fig. 6. Internal view of a valve with a convex central area. Arrowhead indicates the rimoportula opening. Fig. 7. Detail of preceding figure showing the fultoportula and rimoportula openings. Note costae dividing into two or more branches at the valve mantle. Fig. 8. Internal view of a valve with a concave central area. Scale bars: 5 µm (Figs 1–6, 8); 2 µm (Fig. 7).

Figs 9–14. Discostella stelligera var. elliptica from the Río Limay. Figs 9, 10. Light micrographs. Fig. 9. Valve view of a frustule with an elliptical outline. Fig. 10. Valve view of a frustule with an almost circular valve face. Figs 11–14. Scanning electron micrographs. Fig. 11. External valve view. Fig. 12. Detail of valve mantle showing the external openings of fultoportulae (arrowheads). Fig. 13. Internal valve view. Arrowhead indicates the rimoportula opening. Fig. 14. Detail of internal valve mantle showing the fultoportula and rimoportula openings. Note branching costae. Scale bars: 5 µm (Figs 9–11, 13); 2 µm (Figs 12, 14).

Figs 15–20. Discostella stelligera var. elliptica from Frenguelli's material. Figs 15, 16. Light micrographs. Fig. 15. External view of valve face. Fig. 16. Internal view of valve face. Figs. 17–20. Scanning electron micrographs. Fig. 17. External view of a valve with an elliptical outline. Fig. 18. External view of a valve with an almost circular valve face. Fig. 19. Detail of external valve mantle showing the fultoportula openings (arrowheads). Fig. 20. Detail of internal of valve face/mantle junction showing the fultoportula and rimoportula openings. Scale bars: 5 µm (Figs 15–18); 2 µm (Figs 19, 20).

Figs 21–26. Discostella glomerata. Figs 21–22. Light micrographs. Fig. 21. Valve view of a valve with a convex central area showing the external fultoportula openings (arrowheads). Fig. 22. Valve view of a valve with a concave central area showing the external fultoportula openings (arrowheads). Figs 23–26. Scanning electron micrographs. Fig. 23. External view of a valve with a convex central area. Fig. 24. External view of a valve with concave central area. Fig. 25. Internal view of a valve with convex central area. Arrowhead indicates the rimoportula opening. Fig. 26. Internal view of a valve with a concave central area. Scale bars: 5 µm (Figs 21, 22); 2 µm (Figs 23–26).

Figs 27–32. Scanning electron micrographs of Discostella pseudostelligera (Figs 27–30) and D. woltereckii (Figs 31–32). Fig. 27. External view of a valve with a convex central area. Fig. 28. External view of a valve with a concave central area. Fig. 29. Frustules in external view. Arrowheads indicate branching interstriae. Fig. 30. Internal valve view showing branching costae (white arrowheads) and the rimoportula opening (black arrowhead). Fig. 31. Discostella woltereckii. External valve view. Fig. 32. Detail of external valve mantle. Scale bars: 2 µm (Figs 27–31); 1 µm (Fig. 32).

Figs 33–38. Discostella sp. 1. Fig. 33 Light micrograph. Valve view. Figs 34–38 Scanning electron micrographs. Fig. 34. External valve view. Fig. 35. Detail of a valve in external view. Note the two rows of pores located beneath the opening of the fultoportulae. Arrowheads point the scattered pores in the hyaline ring betweeen the central and marginal areas. Fig. 36. Detail of the external valve mantle showing the openings of the fultoportulae (arrowheads). Fig. 37. Internal valve view. Arrowhead points the opening of the fultoportulae. Fig. 38. Internal valve view. Arrowhead points costae dividing in two or more branches at the valve mantle. Scale bars: 10 µm (Figs 33, 34); 5 µm (Figs 35, 37, 38); 2 µm (Fig. 36).

Figs 39–43. Discostella sp. 2. Figs 39, 40 Light micrographs. Fig. 39. Valve view focusing central area. Fig. 40. Valve view focusing marginal area. Note the external openings of the fultoportulae (arrowheads). Figs 41–43 Scanning electron micrographs. Fig. 41. External valve view. Fig. 42. Detail of external valve face/mantle junction. Note the distinctive morphology of the external opening of the fultoportulae. Fig. 43. Detail of the marginal area in valve view. Note the forked dorsal branch of the fultoportulae. Scale bars: 5 µm (Figs 39–41); 2 µm (Figs 42, 43).