Home / Bacillariophyceae / Centric / Unicells / Actinocyclus

Home button

Click on images for larger format

Name derivation:

‘Cyclic ray’ (Gr.) – Actino- ray or beam;  cyclus – cyclic

Classification:

Actinocyclus Ehrenberg, 1837.  Of 388 species descriptions only 55 are currently accepted.

Order Coscinodiscales;  Family Hemidiscaceae

 

Morphology:

Unicells 16 – 48 µm diameter, barrel-shaped centric diatom with multiple discoid chloroplasts.  One valve is concave, the other conves.  Punctae on valve faces are arranged in ‘rays’ from the center to the rim.

Similar genera:

 

Habitat:

Aufwuchs (not firmly attached) on seaweeds and in nearshore marine plankton.  Increasingly occurring in eutrophied freshwater lakes including bays of the Laurentian Great Lakes of Canada and USA.

References:

Ehrenberg, C.G.  1837.  Nachricht des Hrn Agassiz in Neuchatel über den ebenfalls aus mikroskopichen Kiesel-Organismen gebildeten Polirschiefer von Oran in Afrika. 1837: 59-61.

Guiry, M.D. and G.M. Guiry  2013.  AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.  http://www.algaebase.org; searched on 10 September 2013.