Planktoniella F.Schütt, 1892

Holotype species: Planktoniella sol (G.C.Wallich) Schütt

Original publication and holotype designation: Schütt, F. (1892). Das Pflanzenleben der Hochsee. Ergebnisse der Plankton-Expedition der Humboldt-Stiftung 1A: 243-314, figs 58-92.

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Description: Cells discoid, solitary (P. sol) or in flat colonies (P. muriformis). A wing of stiffened mucilage (?) is produced around each cell so that it lies in a flat plate. In P. sol the mucilage forms a series of radial chambers and appears to be secreted through the girdle bands. Plastids small and discoid. P. sol is a widespread open ocean form, mainly tropical in distribution, while P. muriformis has only been recorded in tropical coastal regions. Valves discoid, with a flat valve face and a shallow mantle, the lower part of which has modified areolae; fultoportulae lie at the junction between the mantle and valve face. Areolae chambered, opening internally via fine cribra and externally by larger round foramina, which can, however, be partially occluded by siliceous ingrowths arranged in arcs. A single fultoportula occurs near the centre of the valve face and a ring of fultoportulae around the mantle. A singler large rimoportula in P. muriformis occurs slightly internal to the marginal ring of fultoportulae. Internally the rimoportulae and fultoportulae are unexceptional - the fultoportulae tend to be very shallow, almost flush with the surface. Copulae split, with vertical rows of small areolae and a row of larger areolae along the advalvar margin. It is not clear how the chambering/sectoring of the mucilage wing is produced in P. sol, since there seem to be no breaks in the copulae or their areolation, and the spacing of the fultoportulae bears no relationship to the chambers. Emended description (Yang Li & Lundholm in Yue et al., 2021: 1447).

The most recent alteration to this page was made on 2022-03-02 by G.M. 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 marine genus is one of several which have fultoportulae and rimoportulae, and the view might be taken that all could be included in Thalassiosira. However, that genus is already large and extremely diverse and we believe it is preferable to maintain the two genera, on the basis of the extended wing. The two species mentioned above have been discussed in detail by Loeblich et al. (1968), Gerloff (1970) and Round (1972c). Two other species reported in the literature require further study.

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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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G.M. Guiry in Guiry, M.D. & Guiry, G.M. 02 March 2022. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 02 October 2023

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