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Authority

A.Schimp. ex G.Karst. (Karsten, 1905: 124, pl. 17, fig. 12)

Class

Diatomophyceae

Order

Pennales

Family

Thalassionemataceae

Synonyms

Synedra thalassiothrix Cleve ex O.Müll. (Müller, 1877a: 20)
Synedra tabulata var. thalassiothrix Schwarz ex O.Müll. (1877b: 165)
Thalassiosira antarctica var. echinata G.Karst. (Karsten, 1907: 396, pl. 46, fig. 10a–c)
Thalassiothrix longissima var. antarctica Cleve & Möller (1878, No. 125), nom. nud.
Thalassiothrix longissima var. antarctica Cleve & Grunow, in van Heurck (1881, pl. 37, fig. 10), Hallegraeff (1986: 64, figs 15–22)

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Basionym

N/A

Additional References

Hendey (1937: 335), Hustedt (1958: 141), Semina (1981: 147), Hallegraeff (1986: 64, figs 15–22), Hasle & Semina (1987: 181, figs 26–59), Hasle (1990: 133, pl. 17.1, figs 4–6), Hasle & Syvertsen (1997: 266, pl. 58, tab. 67)

Description

Cells needle-like, straight, slightly curved or sigmoidal in girdle view, forming radiating colonies, joined by bent foot poles (one end of frustule); head poles separated. Apical axis 420–5680 µm; transapical axis 1.5–6 µm; foot pole apex rounded; head pole apex rounded but with 2 protruding spines. Areolae in a single marginal row, 12–17 in 10 µm, with complex vela. Row of fine spines, marginal on the vela, pointed towards the head pole, 1–2 in 10 µm, occurring along the frustule but more abundant towards the head pole. Small foramina on valve surface. Labiate process at each apex (see Hasle & Semina, 1987). Chloroplasts numerous, spherical.

Distribution

Heard I.; type locality, Antarctic Ocean, “Challenger” Expedition; Kerguelen (Hustedt, 1958); KERFIX, 50°40’S 68°25’E, Southern Ocean (Kopczyńska et al., 1998); Southern cold-water region (Hasle & Syvertsen, 1997); wide distribution in South Atlantic, Pacific and Indian Oceans (Hendey, 1937).

Comments

Thalassiothrix antarctica can form extensive mats of intertwined cells which have been mistaken for shallow rocks on marine charts (Quilty et al., 1985). Hasle (1990) noted that it often occurs in association with Trichotoxon reinboldii . The closely related T. longissima Cleve & Grunow is a northern, cold-water species.

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