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Authority

(Bailey) Gran (Hensen) Gran (1904: 527, pl. 27, figs 11, 12)

Class

Diatomophyceae

Order

Centrales

Family

Rhizosoleniaceae

Synonyms

Rhizosolenia styliformis var. semispina (Hensen) G.Karst. (Karsten, 1905: 96, pl. 10, figs 4, 4a, 4b), sensu Wimpenny (1946: 277, text fig. 1h, i)

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Basionym

Rhizosolenia semispina Hensen (1887: 84, pl. 5, fig. 39)

Additional References

Gran (1905: fig. 67b; 1908: 55, fig. 67b), Cupp (1943, fig. 50B), Manguin (1960: 268, pl. 5, figs 67, 68; pl. 27, figs 323, 324), Fenner et al. (1976, fig. 6), Priddle & Fryxell (1985: 86, figs A–H), Sundström (1986: 48, figs 19, 20, 114, 116–118), Priddle et al. (1990: 117, pl. 15.1, fig. 4), Tanimura (1992: fig. 3.15), Moisan & Fryxell (1993: 293), Hasle & Syvertsen (1997: 149, pl. 27 pro parte)

Description

Cells solitary or in pairs or chains, long, cylindrical; pervalvar axis 350–775 µm. Valves acutely conical, bilaterally symmetrical, finely areolate; areolae 22–24 in 10 µm. Apical axis 4.2–25 µm (5–12 µm fide Cupp). Process long (often broken during the preparation of material for microscopy), tapering. Otaria and claspers lacking. Intercalary girdle bands finely areolate; areolae 20–23 in 10 µm. Chloroplasts small, numerous.

Distribution

Weddell Sea (Moisan & Fryxell, 1993); Weddell-Scotia Confluence (Garrison et al., 1987).

Comments

Rhizosolenia hebetata f. hebetata is now considered to be the probable resting spore of R. hebetata f. semispina (Priddle et al., 1990). It is unlikely that either form exists in the Southern Ocean.

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