Paralia Heiberg, 1863
Holotype species: Paralia marina (W.Smith) Heiberg
Currently accepted name for the type species: Paralia sulcata (Ehrenberg) Cleve
Original publication and holotype designation: Heiberg, P.A.C. (1863). Conspectus criticus diatomacearum danicarum. Kritisk oversigt over de danske Diatomeer. pp. 1-135, 6 pls. Kjøbenhavn: Wilhelm Priors Forlag.
Description: Cells shortly cylindrical, linked to form straight chains. Plastids several per cell, small, discoid. Commonly found in marine inshore plankton but probably belonging on sandy sediments. A small genus, containing at least two species - the fossil P. sulcata and the extant P. marina. Valves robust, circular, with radial markings on the valve face. Valve face and mantles sharply differentiated. Sibling valves within chains linked via well-developed interlocking ridges and grooves, and by marginal spines; cameo (relief) and intaglio valves occur, comparable with those of Ellerbeckia. The relief valves have stepped mantles. At the ends of each chain are separation valves, with reduced ridges and no marginal spines. Valves composed of a thick inner layer penetrated by tubes, which connect the cell lumen with a series of chambers lying beneath a thinner outer layer; the chambers open to the outside by large holes positioned around the edge of the valve face and on the valve mantle (the inner part of the valve face is non-porous). Copulae numerous, open, bearing slits (P. marina) or without perforation (P. sulcata). Unlike most other genera, the valvocopula does not underlap the epivalve and is only inserted in a shallow groove between the two mantles of the cell. Consequently the copulae are easily detached.The most recent alteration to this page was made on 2015-12-07 by M.D. Guiry.
Taxonomic status: This name is of an entity that is currently accepted taxonomically.
Comments: Many varieties have been described in P. sulcata (e.g. in A. Schmidt 1874-1959, T. 175-178) and require re-investigation, especially in view of the heterovalve occurring in the genus. P. marina is unlikely to be confused with any other living diatom. The heterovalvy and the structure of the valves suggest a close relationship to Ellerbeckia and Trochosira, which can be recognised by placing both in a new family, the Paraliaceae. A detailed account of Paralia is given by Crawford (1979b).
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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in CD format. These AlgaeBase descriptions are now being continually updated, and each current contributor is identified above. The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and particularly the work of Dr Parker.
Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.
Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=44184
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 07 December 2015. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 09 February 2023