Desmarestia J.V.Lamouroux, 1813, nom. cons.
Holotype species: Desmarestia aculeata (Linnaeus) J.V.Lamouroux
Original publication and holotype designation: Lamouroux, J.V.F. (1813). Essai sur les genres de la famille des Thalassiophytes non articulées. Annales du Muséum d'Histoire Naturelle 20: 21-47, 115-139, 267-293, plates 7-13.
Description: Thallus erect, terete, compressed or ligulate, simple or branched, may be several m high, annual or perennial, usually epilithic. Vacuolar sap of the annual species contains sulfuric acid, pH may be as low as 1. Main axial filament with subterminal intercalary growth.and terminated by a feathery end filament eventually lost in mature thalli. Axial filament surrounded by a thick medulla of unpigmented cells formed by downwardgrowing hyphae. Cortex a dense layer of small isodiametric cells containing several lenticulate plastids without pyrenoids. Phaeophycean hairs absent. Unilocular sporangia either subglobular, produced by transformation of surface cells, or ovoid-elongate, formed on stalk cells in elevated sori together with one to 2-celled parapyses. Life history heteromorphic with macroscopic sporophyte and microscopic filamentous branched monoecious or dioecious gametophytes. When dioecious gametophytes are sexually dimorphic, male filaments to 10 µm and female to 30 µm in diameter. Male gametes are motile spermatozoids formed in clusters of club-shaped antheridia. Female gametes are oocytes formed in elongate oogonia. Release of spermatozoids from antheridia and subsequent attraction towards eggs mediated by desmarestene, a sexual pheromone segregated by mature oocytes. Chromosome numbers are n=22-23; 2n=44-46, but higher counts (2n=52-56) have been reported.
Information contributed by: A. F. Peters. The most recent alteration to this page was made on 2015-10-19 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: Silberfeld, T., Rousseau, F. & Reviers, B. de (2014). An updated classification of brown algae (Ochrophyta, Phaeophyceae). Cryptogamie Algologie 35(2): 117-156, 1 fig., 1 table.
Comments: Widely distributed in polar to warm-temperate seas. Dominant and stand-forming in Antarctica and some parts of the Arctic.
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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in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=56
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 19 October 2015. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 26 September 2023