Percursaria Bory de Saint-Vincent, 1823: 393
Holotype species: Conferva percursa C.Agardh
Currently accepted name for the type species: Percursaria percursa (C.Agardh) Rosenvinge
Original publication and holotype designation:B[ory de Saint-Vincent, J.B.G.M.] (1823). Confervées. In: Dictionnaire Classique d'Histoire Naturelle. (Audouin, I. et al. Eds) Vol. 4, pp. 391-393. Paris: Rey et Gravier; Baudouin Frères.
Taxonomic status: currently recognized as a distinct genus.
Description: Mature thallus filamentous and unbranched, largely biseriate, cells of filaments paired and forming two longitudinal rows. Filaments attached to substrate by monostromatic prostrate discs of coalesced branched filaments. Cells of disc mostly isodiametric or slightly elongate. Disc can give rise to several upright filaments. Upright filaments uniseriate at first, later becoming biseriate by a longitudinal division of cells behind the apical cell. Cells of filaments rectangular or slightly rounded, 10 to 25 µm wide by 10 to 40 µm long. Single parietal chloroplast with 1-4 pyrenoids. Life history an alternation of isomorphic gametophytes and sporophytes. Asexual reproduction by quadriflagellated zoospores; sexual reproduction by biflagellated anisogametes. Zoospores 4 to 5 µm wide by 7 to 8 µm long; male gametes ca. 2 µm wide by 6 to 7 um long; female gametes 3 to 4 µm wide by 6 to 7 µm long. Zoospores and gametes sometimes observed to be released from same thallus. Swarmers with stigma and phototactic. Swarmers leave fertile cells in mass while enclosed within a hyaline envelope, from which they burst moments later. Zoospores, zygotes, and gametes (apomictotic and parthenogenetic) develop into prostrate basal discs which later give rise to upright filaments, or directly into upright filaments attached by rhizoidal cells.
Comments: Percursaria is more or less cosmopolitan in temperate waters and tropical waters, in brackish tidepools, lagoons and salt marshes. Epilithic or on other hard substrates, often entangled with floating mats of algae. Percursaria resembles most other members of the Ulvaceae in its life history, early development and cell structure, but differs by never developing beyond the biseriate filamentous stage. Release of swarmers in a hyaline envelope resembles that of Capsosiphon.
NCBI Nucleotide Sequences
Numbers of names and species: There are 5 species (and infraspecific) names in the database at present, of which 1 has been flagged as currently accepted taxonomically.
Names: ('C' indicates a name that is currently 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):
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: http://www.algaebase.org/search/genus/detail/?genus_id=32828
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 23 May 2013.
Algaebase taxon LSID: urn:lsid:algaebase.org:taxname:8340