Gelidium J.V.Lamouroux, 1813, nom. et typ. cons.

Holotype species: Gelidium corneum (Hudson) J.V.Lamouroux

Original publication and holotype designation: Lamouroux, J.V.F. (1813). Essai sur les genres de la famille des Thalassiophytes non articulées. Annales du Muséum d'Histoire Naturelle 20: 21-47, 115-139, 267-293, 7 plates [7-13].

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Description: Thallus cartilaginous, somewhat crispate, 2 to 40 cm tall, composed by one or several erect axes, terete or compressed, distichously, plumously or irregularly branched, red to deep purple, although in some species it can be blackish. Erect axes arise from cylindrical or compressed, branched or unbranched creeping axes with numerous short haptera extending as individual axes or forming massive disc-like holdfasts. Plants sometimes occur in mats of algal turf with extensive basal parts or in more discrete clamps. The erect fronds can be cylindrical at the base, subcylindrical above and frequently compressed at their apical ends. The cortex has several rows of pigmented cells, the smaller usually toward the outside, mostly 2-15 µm diam. On surface view they may have regular or irregular arrangement. The medullary cells are generally rounded in cross section, up to 30 µm diameter, colourless, compacted or loosely appressed. Elongated, colourless cells, known as rhizines, rhizoidal filaments or hyphae, are thick-walled, up to 5 µm diameter and 200 µm long,located in the medullary and/or cortical tissue, sometimes varying in number and position within species. The tetrasporangia in the sori occupy the entire, somewhat expanded or broadly rounded tips of lateral branches or main axes. Fertile branches can be simple or pinnately compound, somewhat twisted and densely congested They often have sterile margins. Tetrasporangia are cruciately divided, up to 35 µm in diameter, and arranged with or without order in the sori. The carpogonial filament is unicellular, fusing with adjacent cells after fertilization. The cystocarp protrudes equally on both surfaces of the branch, usually with one or, more rarely, several openings on each surface of the frond. Occasionally, two cystocarpic cavities coalesce laterally, forming enlarged cystocarps of up to 1 mm long.

Information contributed by: B. Santelices; modified by M.D. Guiry. The most recent alteration to this page was made on 2017-01-20 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: Boo, G.H., Le Gall, L., Miller, K.A., Freshwater, D.W., Wernberg, T., Terada, R., Yoon, K.J. & Boo, S.M. (2016). A novel phylogeny of the Gelidiales (Rhodophyta) based on five genes including the nuclear CesA, with descriptions of Orthogonacladia gen. nov. and Orthogonacladiaceae fam. nov. Molecular Phylogenetics and Evolution 101: 359-372, 6 figs.

Comments: An intertidal to deep subtidal genus of cold to tropical waters worldwide. Geographically the most widespread genus in the Gelidiaceae. Seemingly absent from artic and subantarctic waters.

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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. 20 January 2017. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 19 June 2024

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