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Figure 1.


Figure 2.

Species Name: Azpeitia nodulifera
Common Name: None
Synonymy: None
  1. TAXONOMY

    Kingdom Phylum/Division Class: Order: Family: Genus:
    Protista Bacillariophyta Coscinodiscophyceae - - Azpeitia

    Species Description

    Fryxell & Sims (in Fryxell et al. 1986) revised the taxonomy of this (formerly Coscinodiscus) and related species. It is a heavily silicified cylindrical species with circular flat valves and a vertical mantle. The main distinguishing feature of the genus is the presence of a rimoportula at or near the valve center (Fig. 1, modified from Hustedt 1931), with an adjacent areola visibly depressed and larger than the others (Fig. 2, modified from Shiono & Koizumi 2002). According to Fryxell et al. (1986), the depressed areola is where the rimoportula of the sibling valve is fitted. There is also a ring of rimoportulae around the valve at the margin. The areolae are arranged in radial rows, with both larger and smaller areolae over the valve surface.

    Cell diameter is usually 35-48µm, though Fryxell et al. report a range of 20-102µm. There are 5-9 areolae in 10µm, and about 7-10µm between rimoportulae around the margin (not visible in the light microscope). It is found rarely in the IRL, and probably is advected in through the inlets from offshore, since it is commonly found in the Gulf Stream. Except for one Antarctic species, the five extant species of Azpeitia are confined to tropical-subtropical oceanic waters. Shiono & Koizumi (2002) provide further observations on this species, along with its geological occurrence. Azpeitia nodulifera is similar to A. barronii, which differs in having uniformly sized areolae over most of its valve surface.

  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

    Fryxell GA, Sims PA, Watkins TP. 1986. Azpeitia (Bacillariophyceae): Related genera and promorphology. ASPT Syst Bot Monogr 13:1-74. DOI: 10.2307/25027634.

    Shiono M, Koizumi I. 2002. Taxonomy of the Azpeitia nodulifera group in late Neogene sediments from the northwest Pacific Ocean. Diat Res 17:337-361. DOI: 10.1080/0269249x.2002.9705553.

Unless otherwise noted, all images and text by PE Hargraves
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Page last updated: 28 April 2015

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