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Figure 1


Figure 2.


Figure 3.

Species Name: Extubocellulus spinifer (Hargraves & Guillard) Hasle, von Stosch & Syvertsen
Common Name: None
Synonymy: None
  1. TAXONOMY

    Kingdom Phylum/Division Class: Order: Family: Genus:
    Protista Bacillariophyta Mediophyceae - - Extubocellulus

    Species Description

    This species is seen most commonly as a contaminant in isolated cultures of other species. Cells are rectangular in girdle view (Fig. 1, 3-cell chain and valve, modified from Hasle et al.; Fig. 2, 4-cell live chain of type culture F8). Individual cells are apparently united by minute spines (Fig. 1, left; Fig. 3, TEM of valve), though cells in a chain are easily separated. The valves are broadly lanceolate or elliptical with two oculluli at the apices (Fig. 3, arrow). Occasionally in culture some elliptical cells have three ocelluli. According to Hasle et al. (1983), each ocellulus is slightly raised above the valve surface and has 7-10 tubes (“porelli”) (Fig. 3, arrow). The valve surface is covered with numerous scattered pores (Fig. 1, right; Fig. 3).

    Its small size means it is normally overlooked in natural samples. The apical axis is about 2-7µm and the transapical axis is 2.0-3.2µm (Hargraves & Guillard 1974). The pervalvar axis depends on the number of girdle bands and is about 4-10µm. There is one parietal chloroplast, almost filling the cell (Fig. 2). The species was first described from isolates in a culture collection, but its distribution in nature is unknown. It has been found in cold temperate waters and the tropics (Hasle et al. 1983) of the Atlantic Ocean, nominally benthic but often in the coastal plankton. It also occurs along the Australian coast and has been reported from China and Antarctica (Saunders et al. 2010). Likewise, its distribution in the IRL system is unknown but it was found in the Vero Beach area.

  2. HABITAT AND DISTRIBUTION

    No information is available at this time

  3. LIFE HISTORY AND POPULATION BIOLOGY

    No information is available at this time

  4. PHYSICAL TOLERANCES

    No information is available at this time

  5. COMMUNITY ECOLOGY

    No information is available at this time

  6. ADDITIONAL INFORMATION

    No information is available at this time

  7. REFERENCES

    Hargraves PA, Guillard RRL. 1974. Structural and physiological observations on some small marine diatoms. Phycologia 13:163-172.

    Hasle GR, von Stosch HA, Syvertsen EE. 1983. Cymatosiraceae, a new diatom family. Bacillaria 6:9-156.

    Saunders K, Lane C, Cook S, McMinn A, Hallegraeff GM. 2010. Benthic Diatoms. In: Hallegraeff GM et al., Eds. Algae of Australia. CSIRO Publishing, Melbourne. pp. 83-144.

Unless otherwise noted, all images and text by PE Hargraves
Editing and page maintenance by LH Sweat
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Page last updated: 28 April 2015

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