Rocella Hanna, 1930
Holotype species: Rocella gemma Hanna
Original publication and holotype designation: Hanna, G.D. (1930). A new genus of Silicoflagellata from the Miocene of Lower California. Journal of Paleontology 4: 415-16, Pl. 40, Fig. 8-18.
Fossil: This is a genus of fossil species, or a genus with a fossil type species, or a genus the type species of which was originally described as a fossil.
Description: Cells discoid. Marine fossil, from Oligocene to Miocene. A small genus, probably planktonic. Valves circular, flat, with short downturned mantles. Mantle edge thick, almost septum-like, crimped in some valves. Central areolae large, marginal and mantle areolae decreasing in diameter. Our material is too eroded to have vela but small spines, around the edges of the areolae point to their existence. Internally there is a conspicuous central 'plate' of silica with thick ribs branching and running out to join the inwardly developed mantle. A central rimoportula opens internally on a slight protruberance and externally by means of a simple large pore. A further pore is present internally adjacent to the rimoportula in our material. Cingulum incompletely observed but copulae apparently complete, narrow with a single row of areolae and at least the valvocopula bearing an internal flange.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 systematics of this genus have given us some problems and finally it was decided to allocate it to a new family. The simple central rimoportula, the internal ribbing and the structure of the valvocopula make it difficult to place this genus in any previously described family - further studies are required on this and many other fossil genera before relationships can be clarified.
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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in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.
Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=46176
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 07 December 2015. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 11 December 2023