Azpeitia M.Peragallo, 1912
Lectotype species: Azpeitia temperi M.Peragallo
Currently accepted name for the type species: Azpeitia antiqua (Pantocsek) P.A.Sims
Original publication: Tempère, J. & Peragallo, H. (1912). Diatomées du Monde Entier, Edition 2, 30 fascicules. Fascicule 20-23. pp. 305-352. Arcachon, Gironde: Chez J. Tempère.
Description: Cells discoidal, solitary. A genus of species formerly included in Coscinodiscus but separated on the basis of possessing a central 'nodule'. Plastids not observed. Marine, planktonic; modern species tend to be tropical/subtropical in distribution and many fossil species are recorded, also from areas believed to have been tropical. Valves circular (triangular and multiangular in some fossil forms), flat, with a shallow but distinct valve mantle and often with a conspicuous raised central tube; immediately adjacent to this is a depression, into which the external tube of the sibling valve fits. The tube is the external extension of the central rimoportula. A distinct annulus is present in some fossil species (P.A. Sims, personal communication). Areolae in radiating rows, loculate. The inner openings are round foramina with raised rims, both towards the valve interior and towards the loculus itself; externally there are depressed cribra. The edge of the valve face is modified to form a solid ring of silica, within or below which the rimoportula openings are located. In A. africanus each opening extends into a circumferential slit. The areolae continue beneath the ring and tend to change shape, becoming diamond-shaped, often with one point truncated. Rimoportulae shortly stalked; one central rimoportula and others in a ring around the valve face/mantle junction. Copulae apparently plain.
The most recent alteration to this page was made on 2024-10-01 by G.M. Guiry.Taxonomic status: This name is of an entity that is currently accepted taxonomically.
Most recent taxonomic treatment adopted: Stoermer, E.F. & Julius, M.L. (2003). Centric Diatoms. In: Freshwater Algae of North America. (Wehr, J.D. & Sheath, R.G. Eds), pp. 559-594. San Diego: Academic Press.
Comments: The structure of the valve clearly places this genus in the Coscinodiscaceae but the central structure and distinct valve rim make a separate genus preferable. When the remainder of the species referred to Coscinodiscus are examined it is likely that others will be transferred to Aspeitia; we have observed several as yet unidentified species with conspicuous central rimoportulae and complex marginal thickenings. Certainly the common 'Coscinodiscus' nodulifer has to be transferred to Azpeitia and these are illustrated in Figs f-i. 'C.' furcatus also belongs here. Many species are important indicator species in the fossil record (Eocene to Recent). Fryxell et al. (1986) place this genus in the Hemidiscaceae, since some of the fossil species have a pseudonodulus.
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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.
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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.
Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=45157
Citing AlgaeBase
Cite this record as:
G.M. Guiry in Guiry, M.D. & Guiry, G.M. 01 October 2024. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 22 November 2024
