Brightwellia Ralfs, 1861

Holotype species: Brightwellia coronata (Brightwell) Ralfs

Original publication and holotype designation: Pritchard, A. (1861). A history of infusoria, including the Desmidiaceae and Diatomaceae, British and foreign. Fourth edition enlarged and revised by J. T. Arlidge, M.B., B.A. Lond.; W. Archer, Esq.; J. Ralfs, M.R.C.S.L.; W. C. Williamson, Esq., F.R.S., and the author. pp. [1]-xii, [1]-968, 40 pls [I-XV]. London: Whittaker and Co..

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Description: A fossil genus in which whole cells have not been seen. Present in sediments of Oligocene to Eocene age. Valves round, shallow and saucer-like, with a ring of radially elongate (oval) openings externally separating a central zone of areolae from a marginal zone. Areolae loculate, opening internally by rimmed foramina and externally through cribra. The cribra probably have large central pores surrounded by a ring of smaller pores; our specimens were eroded but there appear to be bars occluding the pores. The pores form curving rows, in spite of 'belonging to' different areolae. A small plain central area is present. The inner foramina are rather irregularly arranged in the centre but in radial rows in the marginal region. The large oval openings seen on the outside seem to open into chambers with a single small, round internal foramen. The ring of chambers forms a more expanded part of the valve which is revealed internally as an annular swelling. Close to the valve edge there are small pores which are almost certainly eroded rimoportulae. The cingulum is unknown.

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.

Most recent taxonomic treatment adopted: Nikolaev, V.A., Kociolek, J.P., Fourtanier, E., Barron, J.A. & Harwood, D.M. (2001). Late Cretaceous diatoms (Bacillariophyceae) from the Marca Shale member of the Moreno Formation, California. Occasional Papers of the California Academy of Sciences 152: 1-119, 39 plates.

Comments: The valve structure is 'coscinodiscoid' with the addition of the ring of enlarged chambers. Hustedt's (1927-66) illustration shows hexagonal chambers. The genus also shows distinct similarities to Craspedodiscus, which also has a ring of enlarged areolae (see Gombos, 1982), whilst a central cluster of such chambers occurs in Hyperion (Gombos, 1983). These developments of the valve areolae into localised enlarged chambers seem to be a characteristic of fossil genera. Andrews (1986) has reviewed and illustrated several Brithgwellia species, and discusses the relationships and distribution of the genus.

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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.

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M.D. Guiry in Guiry, M.D. & Guiry, G.M. 07 December 2015. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 02 March 2024

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