Hydrosera Wallich, 1858
Lectotype species: Hydrosera triquetra Wallich
Original publication:Wallich, G.C. (1858). On Triceratium and some allied forms, with figures of the same. Quarterly Journal of Microscopical Science 6: 242-253, pls Xii, XIII.
Type designated in Sournia, A. (1987). Atlas du phytoplancton marin. Volume II. Diatomophycées. Vol. 2 pp. 1-215. Paris: Éditions du Centre National de la Recherche Scientifique 15, quai Anatole France - 75700 Paris.
Taxonomic status: currently recognized as a distinct genus.
Gender: This genus name is currently treated as feminine.
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: -119, 39 pls.
Description: Cells triangular and undulate in valve view, rectangular in girdle view; forming short chains by mucilage pads secreted at all three valve angles; attached to the substratum by secretion at one angle. Plastids: numerous, elliptical platelets (Li & Chiang, 1977). A marine epiphytic genus usually found in estuarine situations; it may penetrate upstream in rivers and even into other freshwater sites (Li & Chiang, 1977). Generally regarded as tropical but now recorded in the R. Thames, U.K. A small distinctive genus with two commonly reported species. Valves triangular, their sides undulate. Valve face flat, curving into a fairly deep mantle; both valve face and mantle coarsely areolate, the areolae being somewhat smaller on the mantle. Pseudocelli on each corner, sometimes with small blunt spines around the outer rim; similar projections may occur on other parts of the valve. Areolae loculate, with foramina externally and small round pores internally, the inner pores forming rows radiating from the valve centre. Small domed structures on the outer valve face in the pits between the outer ornamentation. No vela have been detected; nor did Li & Chiang find any though further investigation is necessary. Valve mantle edge plain. The valve has one conspicuous stalked rimoportula, with an S-shaped slit internally. Plain ridges or folds (pseudosepta) extend across the bases of the three corners of the triangular valve. Between the valve mantle and the rimoportula, which is located opposite one of the central undulations of the wall, is a region with three cavities and a short ridge (the cavities were termed pseudonoduli by Li & Chiang, 1977). The opening of the rimoportula and any connection with the bases of the cavities are not obvious from the outside. Copulae closed, finely porous, with a fimbriate edge on the valvocopula; four(?) per cell. Li & Chiang report a complex overlapping of the valvocopula onto the pseudosepta.The most recent alteration to this page was made on 8 May 2018 by M.D. Guiry.
Comments: The 'psedonoduli' do not appear comparable to those in Actinocyclus. The internal folding of the valve, loculate structure and small domed external openings in the primary layer of the wall are reminiscent of other Biddulphiaceae though the relationships of the genera are unclear. Further details are given in Qi (1984) and Qi et al. (1984).
Numbers of names and species: There are 10 species names in the database at present, as well as 1 infraspecific names. Of the species names, 3 have been flagged as accepted taxonomically on the basis of the listed literature under the species name. In some instances, opinions on taxonomic validity differ from author to author and users are encouraged to form their own opinion. AlgaeBase is a work in progress and should not be regarded as a definitive source only as a guide to the literature..
Names: ('C' indicates a name that is accepted taxonomically; 'S' a homotypic or heterotypic synonym; 'U' indicates a name of uncertain taxonomic status, but which has been subjected to some verification nomenclaturally; 'P' indicates a preliminary AlgaeBase entry that has not been subjected to any kind of verification. For more information on a species click on it to activate a link to the Species database):
Click here to also show infraspecific names in the list below.
Verification of data
Users are responsible for verifying the accuracy of information before use, as noted on the website Content page.
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.
Created: 11 April 2002 by M.D. Guiry
Verified by: 08 May 2018 by M.D. Guiry
Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=43684
Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2020. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 15 August 2020.