Acrothrix Kylin, 1907
Holotype species: Acrothrix gracilis Kylin
Original publication and holotype designation: Kylin, H. (1907). Studien über die Algenflora der schwedischen Westküste. Akademische Abhandlung. pp. [i]-iv, 1-287, 7 pls. Upsala: K.W. Appelbergs Buchdruckeri.
Request PDFDescription: Erect thalli irregularly alternately branched several times, somewhat slimy, up to 50 cm in height and 1.5 mm in diameter, olive in color, solid in the terminal part and hollow in the middle and lower parts, haplostichous, constructed of a single central axial filament with trichothallic growth, medullary layer and cortical layer. Cells of central axial filaments long cylindrical, nearly hyaline, provided with terminal trichothallic hair. Medullary layer composed of 2-3 layers of large hyaline cells. The cortical layer composed of cortical cells, assimilatory filaments, lateral hairs and unilocular sporangia. Assimilatory filaments formed from a central axial filament near the apex and also from cortical cells in the middle and lower parts of the thallus. cells of assimilatory filaments contain several chloroplasts with pyrenoids. The number of cells and the shape of the assimilatory filaments considerably variable mainly according to the age of the plant. Phaeophycean hairs abundant in young plants. Unilocular sporangia sessile on the basal cells of assimilatory filaments or on the cortical cells with a stalk cell and ovoid in shape. Plurilocular sporangia not observed on erect thallus. A. norvegica and A. novae-angliae reported to be conspecific with A. gracilis. A. gracilis shows an asexual, heteromorphic, monophasic life history, while A. pacifica shows sexual, heteromorphic life history with upright gametophytes. A. pacifica differs from A. gracilis in the morphology of assimilatory filaments, epiphytic nature and in the life history.
Information contributed by: H. Kawai. The most recent alteration to this page was made on 2021-02-09 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: Distributed in the cold and temperate area of northern hemisphere. Epilithic or epiphytic (predominantly on Chorda filum in A. pacifica), subtidal and summer annual.
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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=32914
Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 09 February 2021. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 23 November 2024
