Gracilariopsis E.Y.Dawson, 1949

Holotype species: Gracilariopsis sjoestedtii (Kylin) E.Y.Dawson

Currently accepted name for the type species: Gracilariopsis andersonii (Grunow) E.Y.Dawson

Original publication and holotype designation: Dawson, E.Y. (1949). Studies of the northeast Pacific Gracilariaceae. Occasional Papers of the Allan Hancock Foundation 7: 1-105, 25 plates.

Description: Plants of the largest species reach 40 cm in length. Thalli are terete and erect from a discoid holdfast. Carpogonial branches are as for the family, as is the formation of a primary fusion cell composed of the carpogonium and up to six adjacent sterile gametophytic cells. A secondary fusion cell is absent, the gonimoblasts arising from the primary fusion cell. Secondary pit connections only link the basal cells of the carposporophyte with specially modified cells on the floor of the cystocarp cavity, there being no "nutrient tubular cells" as occur. Carposporangia form in chains at the periphery of the sterile gonimoblasts. Spermatangial mother cells occur in pairs or groups of 3 on outer cortical bearing cells and each cuts off a single spermatangium by a transverse division.

Information contributed by: G.T. Kraft & M.D. Guiry. The most recent alteration to this page was made on 2021-09-17 by M.D. Guiry.

Taxonomic status: This name is of an entity that is currently accepted taxonomically.

Gender: This genus name is currently treated as feminine.

Most recent taxonomic treatment adopted: Lyra, D. de M., Iha, C., Grassa, C.J., Cai, L., Zhang, H.G., Lane, C., Blouin, N., Oliveira, M.C., Nunes, J. M de C. & Davis, C.C. (2021). Phylogenomics, divergence time estimation and trait evolution provide a new look into the Gracilariales (Rhodophyta). Molecular Phylogenetics and Evolution 165(107294): [1-14], 4 figs.

Comments: Long considered a genus indistinguishable from Gracilaria, Gracilariopsis has been reinstated by Fredericq and Hommersand (1989), who emphasize four differences between the two genera which they consider important. Fusion cells in Gracilariopsis incorporate only the cells immediately flanking the carpogonium, whereas in Gracilaria additional gametophytic cells are later added. Nutrient tubular cells characteristic of Gracilaria are lacking in Gracilariopsis, and the carposporangial chains of the latter are straighter and more regularly organized. Spermatangial mother cells are formed from superficial cortical cells in Gracilariopsis, whereas in Gracilaria they are said to arise from adventitious filaments arising on subsurface (i.e. intercalary) cortical cells.

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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. 17 September 2021. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 10 August 2022

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