Asteromphalus Ehrenberg, 1844

Holotype species: Asteromphalus darwinii Ehrenberg

Original publication: Ehrenberg, C.G. (1844). Untersuchungen über die kleinsten lebensformen im quellenlande des Euphrats und Araxes, so wie über eine an neuen formen sehr reiche marine tripelbildung von den Bermuda-Inseln. Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königlich-Preussischen Akademie der Wissenschaften zu Berlin 1844: 253-275, 1 pl.

Type designated in: Boyer, C.S. (1927). Synopsis of North American Diatomaceae. Part I. Coscinodiscatae, Rhizosolenatae, Biddulphiatae, Fragilariatae. Proceedings of the Academy of Natural Sciences of Philadelphia 78(Suppl.): 1-228.

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Description: Cells discoid to slightly pear-shaped, rarely naviculoid, undulate in girdle view. Plastids reported as numerous discoid bodies. Marine, planktonic in warm waters but never occurring in large quantity: about 35 species. Valves shaped like watch-glasses, without a distinct valve mantle; some species slightly extended along one radius to give an obovate form. The valve has very distinctive plain rays (see Gombos, 1980, for terminology) alternating with areolate areas. The broad inner parts of the plain sectors abut at the centre or off-centre on the valve face; one ray differs from the others (the median ray of Greville, 1860) having a thinner distal section and forming a focus from which the others radiate. At the marginal (outer) end of each ray is a thin plate which is usually lost leaving a large aperture (ray hole); below this is a smaller opening, representing the external aperture of a rimoportula. This is absent on the median ray but here the thin plate is missing, the outer part of the process is morphologically different and the rimoportula must open into the ray itself for a process can be seen on the inside. The rays are long chambers opening internally by ray slits which taper towards the margin. The valve edge is plain usually with a notch offset from the end of the thin ray. The areolae are loculate. Externally their apertures are variable, though basically cribrate. Internally they have simple foramina. Flattened kidney-shaped rimoportulae occur marginally, opposite the ends of the ray slits; the rimoportula opposite the narrow ray slit is often larger. In some species small rimoportulae also occur near the central plain area. Copulae not investigated.

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: Scott & Thomas (2005: 13) record this genus as being a member of the Order Centrales. This genus and Asterolampra are clearly closely related and both are found in tropical oceans. The rare 'naviculoid' forms were described by Kolbe (1955) as Liriogramma but are only boat-shaped species of Asteromphalus - they occur in the Gulf of California (Round, unpublished observation).

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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 24 April 2024

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