Bicosoeca H.J.Clark, 1866

Lectotype species: Bicosoeca lacustris H.J.Clark

Original publication: Clark, H.J. (1866). On the spongia ciliatae as infusoria flagellata [Preliminary abstract]. Memoirs of the Boston Natural History Society 1: 16.

Type designated in: Grassé, P.P. & Deflandre, G. (1952). Ordre des Bicoecidea (Bikoecidae S. Kent, 1880). In: Traité de Zoologie. Phylogenie, Protozoaires : généralités, Flagellés. (Grassé, P.P. Eds) Vol. 1(1), pp. 599-601. Paris: Masson et Cie.

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Description: Cells colorless, spherical to ellipsoidal, single-celled or united in colonies. Cells bearing 2 unequal blunt flagella, inserted antero-laterally next to a peristomal structure that resembles a protruding lip surrounded the cytostomal area. The shorter, smooth flagellum posteriorly directed, with a tip attached to a lorica. The longer, hairy flagellum is held in a slight curve in front of the cell, beating with low amplitude, and is active in swimming and feeding. When a cell is disturbed, the short flagellum contracts, and the cell is withdrawn to the bottom of the lorica, while the long flagellum is rolled up into a tight coil at the anterior end of the cell. This behavior is diagnostic. Lorica organic, amorphous or fibrous, of variable shape, size and thickness, providing most of the taxonomic characters for the genus. Some loricas are made of a thin, transparent, randomly woven matrix. Others are thicker, more regularly woven and sometimes patterned with stripes (Kristiansen 1972). The shape of the lorica is visible by light microscopy, but details of its structure can usually be resolved only by electron microscopy. Reproduction by cell division; one of the daughter cells escapes and forms a new lorica, starting with the base (or stalk). In species where daughter cells tend to remain stuck to the mother lorica, colonies may develop. Found mostly in fresh water (a few known from brackish and marine waters).Some species are very common and widely distributed, but often overlooked. The order Bicocoecales, including the genera Bicosoeca (family Bicosoecaceae, Cafeteria and Pseudobodo (Cafeteriaceae) has been accommodated in the class Chrysophyceae by several authors ( Moestrup 1995). Others assigned Bicosoeca and related genera to a separate class of heterokonts called Bicosoecophyceae (Loeblich and Loeblich 1978), Bicoecea (Cavalier-Smith 1997) or Bicosoecida (=Bicoecida; Margulis and Schwartz 1998). Most recently, additional genera have been accommodated in the Bicosoecales (Bicosoecida), such as Acronema (Teal & al.1998) and Siluania (family Siluaniaceae; Karpov et al.1998). Several genera of colorless flagellates, in which the anterior flagellum lacks flagellar hairs, have also been suggested to have bicosoecid affinities, e.g. Caecitellus Patterson, Nygaard, Steinberg and Turley, or genera included in the Pseudodendromonadida (Adriamonas Verhagen, Zölffel, Brugerolle and Patterson, Cyathobodo Petersen and Hansen, Pseudodendromonas Bourrelly) (see O'Kelly and Nerad 1998).

Information contributed by: H. R. Preisig. The most recent alteration to this page was made on 2020-03-31 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: Nicholls, K.H. & Wujek, D.E. (2003). Chrysophycean Algae. In: Freshwater Algae of North America. (Wehr, J.D. & Sheath, R.G. Eds), pp. 471-510. San Diego: Academic Press.

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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. 31 March 2020. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 20 May 2024

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