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Authority

(Grunow) Willi Krieg., in Helmke & Krieger (1954: 17, pl. 187–189)

Class

Diatomophyceae

Order

Pennales

Family

Bacillariaceae

Synonyms

Fragilaria nana Steem.Niels. (Steemann Nielsen, 1935: 74, fig. 2a, b)
Fragilariopsis cylindrus var. planctonica Willi Krieg., in Helmske & Krieger (1954: 17, pl. 188, 189)
Fragilariopsis cylindrus f. minor Manguin (1960: 298, pl. 12, fig. 127)
Fragilariopsis linearis (Castrac.) Hust. var. intermedia Manguin (1960: 298, p1. 2, fig. 129)
Fragilariopsis nana (Steem.Niels.) Paasche (1961: 201) pro parte
Nitzschia cylindrus (Grunow) Hasle (1964: pl. 3, fig. 3)
See Hasle (1965b) for full synonymy, LM and EM, descriptions, discussion of nomenclatural problems and distribution.

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Basionym

Fragilaria cylindrus Grunow, in Cleve (1883: 484, pl. 37, fig. 64a–c)

Additional References

Buck & Garrison (1983: 1264, fig. 7), Hasle & Medlin (1990c: 181, pl. 24.6, figs 6–12), Moisan & Fryxell (1993: 493), Hasle & Syvertsen (1997: 302, pl. 68)

Description

Cells solitary or chain-forming, attached by the valve surfaces, linear in valve view, with rounded ends; apical axis 3–48 µm; transapical axis 2–4 µm. Transapical striae 13–17 in 10 µm, straight. Interstrial membranes perforated by minute areolae, either scattered or in 2 or 3 (exceptionally 4) rows, 60–70 in 10 µm. Fibulae present as continuations of the costae. Canal raphe present.

Distribution

Sea-ice near Davis Station, East Antarctica (Archer et al., 1996b); type locality, Tindingen, Greenland, Cape Wünkerema near Bering Strait (Cleve, 1883); KERFIX, 50°40’S 68°25’E, Southern Ocean (Kopczyńska et al., 1998); Zemlya Frantsa-Iosifa (Franz Josef Land), Arctic Ocean (Grunow, 1884); bipolar, cold-water species mainly confined to Antarctic and Arctic waters (Hasle, 1965b); Weddell Sea (Buck & Garrison, 1983); Weddell-Scotia Confluence (Garrison et al., 1987); Benguela Current (Heiden & Kolbe, 1928).

Comments

Hasle (1965b) explained that when Paasche transferred Fragilaria nana Steem.Neils. to Fragilariopsis, he retained the epithet nana with some reservation, suspecting that more than one species had been identified as Fragilaria nana in the Norwegian phytoplankton studies of the 1950s and 1960s. The diagnosis of Fragilariopsis nana (Steem.Neils.) Paasche apparently included the linear-valved Fragilaria nana Steem.Neils. Fragilariopsis nana is now separated into two taxa, viz. the linear-valved Fragilaria nana (a synonym of Fragilariopsis cylindrus) and the elliptical-lanceolate -valved Fragilariopsis pseudonana Hasle.

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