Cottoniella Børgesen, 1919

Holotype species: Cottoniella arcuata Børgesen

Original publication and holotype designation: Børgesen, F. (1919). The marine algae of the Danish West Indies. Part 3. Rhodophyceae (5). Dansk Botanisk Arkiv 3: 305-368, Figs 308-360.

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Description: Thallus erect, slender and delicate, up to 10-12 cm high, with endogenous branching and axes not corticated or corticated by rhizoid filaments only in the lower parts; fixed to the substratum by apterans or by rhizoids issued from the prostrate portion of the axis. Growth by a prominent transversely dividing apical cell; each axial cell has 4 periaxial cells (up to 5 in C. sanguinea Howe; up to 6 in C. libyensis); of these the ventral (or abaxial) is formed first, then the two lateral ones are formed, and the dorsal (or adaxial) is formed last; however in some taxa (C. fusiformis Børgesen, C. libyensis and C. filamentosa var. algeriensis) the two lateral periaxial cells are formed first and then the other two (the dorsal and the ventral). The two lateral periaxial cells on their external side each form two marginal cells (flanking cells) which do not undergo further divisions; in some species the flanking cells are either absent (as in C. sanguinea Howe and C. triseriata Hollenberg) or present discontinuously (as in C. arcuata Børgesen). The monosiphonic filaments are of endogenous origin (also exogenous in C. filamentosa var. algeriensis, C. fusiformis, C. libyensis, C. triseriata), unbranched, 1-2 per segment (3 in C. triseriata) and produced on the side concave of the axes; the basal cell of the monosyphonic filaments forms secondary synapses with the neighboring periaxial cell. Monoecious gametophytes. Spermatocysts grouped in sori that cover the surface of the fertile branch except for the sterile marginal rows (the flanking cells of the fertile branch) and for the sterile terminal filament. The carpogonial branches are produced in the upper part of the axes and branches with indeterminate growth; the cystocarps (one per axis) are globose, subsessile, ostiolate and have a well-developed pericarp. The tetrasporocysts, with tetrahedral division, are produced, two per segment, in short lateral stichidia.

Information contributed by: Cormaci & al. (2023: 565-6).. The most recent alteration to this page was made on 2023-12-13 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 neuter.

Most recent taxonomic treatment adopted: Nizamuddin, M & Godeh, M. (1990). A first record of the genus Cottoniella Børgesen (Ceramiales, Rhodophyta) from Libya. Pakistan Journal of Botany 22(1): 24-35.

Comments: The following two taxa are present in the Mediterranean: C. filamentosa var. algeriensis and C. libyensis.

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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=35528

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 13 December 2023. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 18 April 2024