Stictodiscus Greville, 1861
Lectotype species: Stictodiscus rota (Ehrenberg) Greville
Original publication: Greville, R.K. (1861). Descriptions of new and rare Diatoms. Series I. Transactions of the Microscopical Society, New Series 9: 39-45, pl. IV.
Request PDFType designated in: Boyer, C.S. (1927). Synopsis of North American Diatomaceae, Supplement, Part 2. Naviculatae, Surirellatae. Proceedings of the Academy of Natural Sciences of Philadelphia 79: 229-583.
Description: Cells discoid. Plastids not observed. This is a genus known mainly from fossil marine material. Hustedt (1930) comments on its scarcity and occurrence in deep water habitats. Valves circular, triangular to multiangular. Valve face flat or slightly bowed; mantles distinct but shallow. Areolae in rows radiating from the centre, although often the central area itself is almost devoid of areolae. Raised siliceous thickenings often surround the widely spaced inner areolae externally, while towards the edge of the valve face there can be conspicuous radial thickenings and less prominent tangential ones separating the outer files; a distinct network is visible in the LM. The valve mantle has a similar structure to that of the valve face. No other surface structures present. Internally the valve face can be plain or bear radial and tangential thickenings. No portules or ocelli are present. Copulae not seen.
The most recent alteration to this page was made on 2017-01-30 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: This is a very distinctive genus easily recognised by the valve markings. The early separation of the multiangular forms into Stictodiscella is not recommended. The classification alongside Arachnoidiscus in a Stictodiscineae (Hustedt, 1927-66) or Stictodiscoideae, with several other genera (Simonsen, 1979), may be valid for some species referred to Stictodiscus; others seem further removed from the Arachnoidiscus form. However, it is clear that this and several other circular to multiangular genera need very careful detailed study before final decisions can be made. Most of the nearly 70 spp. listed by VanLandingham (1978) have rarely been recorded and should be checked; there is a possibility that some are resting spores. We thank P.A. Sims for the material photographed here.
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Contributors
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=46285
Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 30 January 2017. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 24 December 2024
