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Authority

(G.Karst.) Nothig & Ligowski, in Jordan et al. (1991: 68, figs 19–29)

Class

Diatomophyceae

Order

Centrales

Family

Rhizosoleniaceae

Synonyms

Rhizosolenia inermis f. rostrata Heiden & Kolbe (1928: 522, pl. 8, fig. 162; pl. 9, fig. 167)
Rhizosolenia rostrata (Heiden & Kolbe) Bunt & E.J.F.Wood (1963: 1255)
Rhizosolenia alata f. curvirostris auct. non Gran (1900: 120, pl. 9, fig. 122), sensu Hasle (1969: 142)
Rhizosolenia alata f. truncata (G.Karst.) Hasle (1969: 142)
Rhizosolenia alata auct. non Brightw. (Brightwell, 1858: 56, pl. 5, fig. 8), sensu Fenner et al. (1976: pl. 13, fig. 1)
Rhizosolenia alata f. indica Nothig, in Nothig & Nothig (1988: 74, fig. 42a, c)

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Basionym

Rhizosolenia truncata G.Karst. (Karsten, 1905: 97, pl. 10, figs 3, 3a)

Additional References

Priddle et al. (1990: 119, pl. 15.4, fig. 4)

Description

Cells solitary or often in long chains of up to 8 cells; individual cells 140–235 µm long, cylindrical; apical axis 16–30 µm diameter. Valves dissimilar; one with a short proboscis, the other with a long one. Short proboscis truncate, angled at c. 45° to pervalvar axis (lateral view), with spinules and a longitudinal slit at tip; claspers equal, protruding. Long proboscis tapered, straight or slightly angled (lateral view), slightly wider, with spinules and a short longitudinal slit just below tip; claspers, when present, equal, protruding. Girdle bands not distinguishable.

Distribution

Prydz Bay, near Davis Station, East Antactica; Drygalski Glacier, Ross Sea; recorded only from Antarctic waters (Jordan et al., 1991); Antarctic Peninsula (Ferreyra & Ferrario, 1983a).

Comments

Ferreyra & Ferrario (1983a) suggested that the long proboscis type is a winter form, and this was confirmed by Jordan et al. (1991).

Five species are currently recognised (see discussion in Hasle & Syvertsen, 1997), although further EM investigations may see taxa of the closely related Rhizosolenia being transferred to Proboscia. Three species have been reported from Antarctic waters, P. alata, P. inermis and P. truncata (Jordan et al., 1991). In the same publication, the authors identified ‘winter’ and ‘spring’ forms of these diatoms, noting that winter forms have a longer proboscis.

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