Cerataulus Ehrenberg, 1844
Holotype species: Cerataulus turgidus (Ehrenberg) Ehrenberg
Original publication and holotype designation: Ehrenberg, C.G. (1843). Beobachtungen des bedeutenden Einflusses unsichtbar kleiner Organismen auf die untern Stromgebeithe, besonders der Elbe, Jahde, Ems und Schelde. 1843: 259-272.
Description: Cells rectangular in girdle view with conspicuous ocelli twisted out of the pervalvar plane. Elliptical or circular in valve view. Plastids numerous, discoidal. A marine genus often found attached to one or more sand grains by mucilage extruded through the ocelli. Also frequently found coated with fine silt and clay particles, sometimes mixed into the plankton but strictly a benthic genus. Valves elliptical or circular and twisted, with large ocelli on short elevations pointing in opposite directions. The torsion varies between slight and extreme and makes the valve margin non-planar. Surface of valve with spines or granules, especially on the mantle. Areolae radiate from the centre. Areolae loculate (see also Ross & Sims, 1971) with fine outer pores and larger round foramina internally. Outer pores clustered into radiating multiseriate rows, except within a central annulus, where they are scattered. The valve mantle may be ornamented with circumferential ridges, 2(4) - sometimes forked exit tubes at the apices of the rimoportulae are situated near the margin of the valve face, midway between or near to the ocelli, one or two on either side of the valve in our specimens. Ocelli with wide plain margins and porelli in sectors. Copulae curved to follow the torsion of the valves, split, with ligulae.
The most recent alteration to this page was made on 2015-05-07 by M.D. Guiry.Taxonomic status: This name is of an entity that is currently accepted taxonomically.
Most recent taxonomic treatment adopted: Cox, E.J. (2015). Coscinodiscophyceae, Mediophyceae, Fragilariophyceae, Bacillariophyceae (Diatoms). In: Syllabus of plant families. Adolf Engler's Syllabus der Pflanzenfamilien. 13th Ed. Photoautotrophic eukaryotic algae Glaucocystophyta, Cryptophyta, Dinophyta/Dinozoa, Heterokontophyta/Ochrophyta, Chlorarachniophyta/Cercozoa, Euglenophyta/Euglenozoa, Chlorophyta, Streptophyta p.p. (Frey, W. Eds), pp. 64-103. Stuttgart: Borntraeger Science Publishers.
Comments: The systematics of this and other 'biddulphioid' taxa needs considerable attention and other species need detailed study, e.g. a triangular species, C. subangulatus, has been described from Oamaru, which Schmidt (1874-1959, taf. 116) considered might be a new genus. Hustedt (1927-66) clearly considered that the degree of torsion of the cell was an important distinction but even this requires further investigation. Only C. turgidus is regularly recorded and VanLandingham has only a few other records. We suggest that C. smithii belongs with other species in the 'reticulata' group of Biddulphia which requires re-investigation since they may form a new genus. C. laevis has already been returned to Pleurosia.
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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera,
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Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.
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Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 07 May 2015. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 22 November 2024
