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Authority

van Heurck (1909: 18, pl. 2, fig. 29)

Class

Diatomphyceae

Order

Pennales

Family

Cocconeidaceae

Synonyms

Cocconeis pellucida sensu A.Mann (1907: 331)
Cocconeis gautieri van Heurck (1909: 17, pl. 2, fig. 30), Frenguelli & Orlando (1958: 82)
Cocconeis litigiosa van Heurck (1909: 18, pl. 2, fig. 28)
Cocconeis schuettii var. minor van Heurck (1909: 19, pl. 2, fig. 32)
Cocconeis schuettii var. litigiosa (van Heurck) Perag. (Peragallo, 1921: 54)

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Basionym

N/A

Additional References

Peragallo (1921: 53), Manguin (1960: 305)

Description

Cells solitary, elliptical; apical axis 50–110 µm; transapical axis 30–70 µm. Transapical striae curved and radiating, uniseriate; areolae poroid to slit-like. Raphe-valve slightly concave; R-valve transapical striae 12 in 10 µm near the margin, 18 in 10 µm near the centre. Raphe a simple straight fissure, expanded slightly at the inner and outer ends, and connecting with an arrow-shaped non-areolate area at outer ends (Fig. c). Pseudoraphe-valve convex near margin, but concave in central area around pseudoraphe. Areas immediately around pseudoraphe and from c. midway from centre to margin are non-areolate (Fig. a); P-valve transapical striae 24–25 in 10 µm near the margin (Fig. b), 20–21 in 10 µm near the centre.

Distribution

In sea-ice and epiphytic on Ballia, coastal waters near Davis Station, East Antarctica; Petermann I., Antarctic Peninsula (Peragallo, 1921).

Comments

Cocconeis cells are solitary and heterovalvate. One valve (the P-valve) is typically convex and bears a pseudoraphe; the other (the R-valve) is concave (or at least less convex than the P-valve) and bears a central raphe-sternum. Valve structure is usually of broad, non-areolate, transapical costae alternating with striae (intercostal areas) that contain uniseriate or multiseriate poroids (areolae). The arrangement of striae and costae on the P-valve often differs from that on the R-valve.

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