Lessonia Bory, 1825

Holotype species: Lessonia flavicans Bory

Original publication and holotype designation: [Dumont] d'Urville, J.[S.C.] (1825). Flore des îles Malouines. pp. [i], [1]-56. Paris: De l'imprimiere De Lebel, imprimeur du Roi.

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Description: Thallus 1-4 m high, perennial. Holdfast discoid, divided and becoming conical, or ligulate, attached by branched haptera, with the stipe branched from the base or higher, often twisted, with each branch bearing a blade. Blades simple, 0.5-2 m long and 1-5 cm wide, ligulate to irregularly elongate, flat, margins denticulate, surface smooth to rugose or corrugate. Growth by longitudinal splitting of the blades, resulting in dichotomous branching of stipe. Blade and stipe with a central, filamentous medulla, extensive cortex of relatively small cells with or without mucilage cavities, and outer layer of meristoderm. Spores produced in unilocular sporangia with paraphyses in extensive sori, produced on both surfaces of blades. Gametophytes dimorphic, dioecious, oogamous, branched uniseriate filaments.

Information contributed by: R.J. Lewis and M.D. Guiry. The most recent alteration to this page was made on 2024-01-09 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: Zuccarello, G.C. & Martin, P. (2016). Phylogeography of the Lessonia variegata species complex (Phaeophyceae, Laminariales) in New Zealand. Algae. An International Journal of Algal Research 31(2): 91-103.

Comments: Lessonia is the only genus in the family Lessoniaceae to occur solely in the Southern Hemisphere, with 4 species recognized from South America and 5 from the south-west Pacific region. These species are morphologically variable, leading to description of many taxa in earlier taxonomic treatments. Several of these species are recently described, and further taxonomic revisions may be necessary. L. vadosa Searles, described from South America, may be conspecific with L. brevifolia J. Agardh, which occurs on the New Zealand subantarctic islands. The species are separated based on holdfast and stipe morphology, blade morphology (e.g. smooth or corrugate), and structural characteristics of the medulla and cortex in blades and stipes. L. nigrescens Bory and L. trabeculata Villouta & Santelices are harvested and exported from Chile for alginate extraction. L. nigrescens is the dominant organism in the low intertidal zone in central Chile while L. trabeculata forms extensive subtidal beds on rocky bottoms at depths of 0.5 to 20 m. Harvesting the upper portions of L. nigrescens greatly reduces its ability to survive, while harvesting entire plants increases grazing on remaining plants and makes neighboring plants susceptible to removal by water movement. Lessonia laminarioides Postels & Ruprecht from the Sea of Ochotsk has been removed from Lessonia and forms the basis for Pseudolessonia (Cho et al 2006).

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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.

Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=42591

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 09 January 2024. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 19 May 2024

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