F. kerguelensis
[ Home ] [ Species descriptions ] [ Climate Archives ] [ Links ] [ Profile ] [ References ]

Fragilariopsis kerguelensis (O'Meara) Hustedt

Heavily silicified, coarsely structured valves. 4-7 (5) transapical costae pr. 10 µm valve length. These ribs are straight in the valve center, but tends to curve somewhat nearer to the poles. The intercostal depressions (membranes) show two rows of very distinct, alternating areolae, spaced transapically 8-10 areolae in 10 µm. The valve is heteropolar along the apical axis, with somewhat pointed apices. This gets more pronounced in larger specimens, while small speciments are almost elliptical with rounded apices. The coarse striation and heavy silicification makes this species reckognizable in girdle view too⁹.

F. kerguelensis is separated from F. ritscheri by its bigger and more widely spaced areolae. F. obliquecostata has even more oblique costae than F. kerguelensis⁹.

Size: 5-11 µm wide, 10-76 µm long⁹.

Occurence: The most widely distributed and frequently occuring Fragilariopsis species in the Southern Ocean. Its distribution ranges from Subantarctic waters to the north, but gets outnumbered by F. cylindrus and F. curta nearer to the Antarctic continent. It prefers oceanic conditions, with more sparse occurences in the extreme inshore areas⁹.

Suggestions or comments? Mail Simon H.H. Nielsen at Simon@npolar.no