Coleochaete Brébisson, 1844, nom. cons.

Holotype species: Coleochaete scutata Brébisson

Original publication and holotype designation: Brébisson, [L.] A. de (1844). Description de deux nouveaux genres d'algues fluviatiles. Annales des Sciences Naturelles, Botanique, Sér. 3 1: 25-31, 2 pls.

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Description: Most commonly found genus of Coleochaetales. Includes forms with prostrate and erect branched filaments, prostrate branched filaments, branched filaments adherent to form pseudoparenchyma, and parenchymatous thalli. Sometimes embedded in mucilage. Some thallus cells bearing distinctive sheathed hairs. Vegetative cell size varies from 5.5 to 38.5 um, depending upon species; antheridia smaller, zygotes larger. Chloroplasts single, parietal, plate-like, with 1 or 2 pyrenoids. Hair cells have circular plastids which may rotate. Nucleus single. Asexual reproduction by biflagellate, scaly zoospores produced singly, eyespots lacking. Sexual reproduction oogamous, occurring at various times in growing season, depending upon species. Oogonia (egg cells) peripheral, each bearing a trichogyne whose length varies among species. Spermatozoids colorless or pale green, emerging from spermatids which are small conical branches in filamentous species, or cells derived from asymmetrical, diagonal divisions of internal cells in parenchymatous species. Spermatids develop proximally to oogonia in monoecious (monoicous) species. Zygotes enlarge, accumulate starch and lipid storage, and become corticated by growth of adjacent thallus cells; the degree of cortication varies among species. In one species, cortical cells have localized wall ingrowths similar to placental transfer cells of embryophytes. Cortical cell walls and other cell walls near zygotes impregnated with resistant polyphenolic material; inner zygote wall with sporopollenin. Meiosis occurs at zygote germination; 8-32 scaly, biflagellate meiospores emerge, settle on substrates, and develop into new thalli. Widespread in freshwater; tropical, temperate and arctic/antarctic; attached to submerged leaves and stems of aquatic macrophytes, thalli of larger algae or inorganic materials. One species occurs endophytically in walls of characean algae. Not of economic use or cause of nuisance blooms. Ultrastructural, biochemical and molecular evidence demonstrates close relationship to ancestry of embryophytes. Derived characters shared with embryophytes include presence of nuclear tufA genes, introns in t-RNA Ala and Ile chloroplast genes, phragmoplasts in dividing cells, and similarities in reproductive development.

Information contributed by: L.E. Graham. The most recent alteration to this page was made on 2023-09-06 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.

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Contributors
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=44107

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 06 September 2023. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 22 November 2024