Smithsonian Marine Station at Fort Pierce

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Figure 1


Figure 2.


Species Name: Minidiscus chilensis Rivera
Common Name: None
Synonymy: None
  1. TAXONOMY

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

    Species Description

    These tiny cells are solitary, drum-shaped, with the diameter usually larger than the pervalvar axis. The valves have incomplete radial rows of poroid areolae (Fig. 1) that begin at the valve margin and extend to about ¼ the valve radius. There is one rimoportula (Fig. 1, 2; SEM, arrowheads) and 3 fultoportulae on the non-areolate and slightly undulate central part of the somewhat undulated valve. A curious single pore is found on a line between the central fultoportula and the single rimoportula (Fig. 1, arrow). This pore is occluded, thus not visible in the valve interior (Fig. 2). The valvocopula is finely punctate, with the puncta arranged in irregular lines oriented in the pervalvar axis (Fig. 1). The known valve diameter range is 3-7.5µm, with most IRL specimens measuring 3.1-4.5µm. There are about 9 radial rows of poroid areolae in 1µm. Of the seven described species in this genus (Quiroga & Chretiennot-Dinet 2004; Kaczmarska et al. 2009), M. chilensis is the most distinctive, but it cannot be positively identified without electron microscopy due to its small size. It has a worldwide distribution, seemingly preferring coastal waters where it may reach over 105 cells per liter. In the IRL it was seen throughout the year. No quantitative estimates were possible, since it co-occurs with the equally small M. comicus and M. trioculatus. Kaczmarska et al. (2009) suggest that its frequent occurrence with attached sediment particles may be part of its lifestyle.

  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

    Kaczmarska I, Lovejoy C, Potvin M, MacGillivary M. 2009. Morphological and molecular characteristics of selected species of Minidiscus (Bacillariophyta, Thalassiosiraceae). Eur J Phycol 44:461-475.

    Quiroga I, Chretiennot-Dinet M. 2004. A new species of Minidiscus (Diatomophyceae, Thalassiosiraceae) from the eastern English Channel. Bot Mar 47:341-348.

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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