Eucheuma J.Agardh, 1847: 16

Classification:
Empire Eukaryota
Kingdom Plantae
Phylum Rhodophyta
Subphylum Eurhodophytina
Class Florideophyceae
Subclass Rhodymeniophycidae
Order Gigartinales
Family Solieriaceae

Lectotype species: Eucheuma spinosum J.Agardh

Currently accepted name for the type species: Eucheuma denticulatum (N.L.Burman) F.S.Collins & Hervey

Original publication:Agardh, J.G. (1847). Nya alger från Mexico. Öfversigt af Kongl. Vetenskaps-Adademiens Förhandlingar, Stockholm 4: 5-17.
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Type designated inSchmitz, F. (1889). Systematische Übersicht der bisher bekannten Gattungen der Florideen. Flora oder Allgemeine botanische Zeitung 72: 435-456, pl. XXI.
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Taxonomic status: currently recognized as a distinct genus.

Description: Plants of the largest species are bushy, reach over 50 cm in length, and can weigh over a kilogram. Thalli are often very fleshy and rigidly cartilagenous when fresh, and are erect from an encrusting base or prostrate to entangled and anchored at many points by haptera. Most bear whorled to scattered, simple to compound spines. In two of the three sections (all but two species), cross sections are composed of a deep pseudoparenchymatous cortex surrounding a filamentous medulla of mixed axial and rhizoidal cells. Members of the section Anaxiferae are pseudoparenchymatous throughout. Carpogonial branches are 3-celled and give rise to a single connecting filament on fertilization. Gonimoblast initials are single or multiple, and cystocarps are strongly protuberant structures enclosed in a thick, ostiolate pericarp and either housed within spinous outgrowths or sessile on the major axes. Carposporophytes consist of a large central fusion cell surrounded by radiating clusters of gonimoblasts interspersed with sterile filaments that link the fusion cell to the filamentous hull lining the inner pericarp. Carposporangia are single and terminal. Tetrasporangia are attached basally or laterally to bearing cells and are scattered or in sori.

Comments: Reproductive anatomy has been detailed by Gabrielson (1983) and Gabrielson and Kraft (1984), and the use of electrophoresis to characterize species was investigated by Cheney and Babbel (1978). A critical review of the genus, including division into three sections, is made by Doty (1988), who also details the commericial properties of their various carrageenans. Doty and Santos (1978) show that gametophytic and sporophytic thalli of Eucheuma and Kappaphycus (as Eucheuma) produce the same carrageenan types, although gel strengths may differ. Greer and Yaphe (1984a, 1984b) have done recent analyses of carrageenan fractions in Chinese and Caribbean species, and Santos (1989) analyzed infrared spectra of carrageenans from all the Eucheuma species recognized by Doty (1988), showing that all members of two of the three sections yield only iota fractions, whereas members of the third sectioncontain either only kappa, or both kappa and beta carrageenans. Physiology and seasonality studies have been made by Glenn and Doty (1981) and Yokochi (1983) respectively. The development of farming procedures for species of Eucheuma (and Kappaphycus) is detailed by Doty (1978, 1979) and Dawes (1987), and growth rates of species in outdoor cultures are measured by Mairh et al. (1986)and Zertuche et al. (1987). Distribution: The type species is widespread in the northern Indian Ocean and the western Pacific from southern Japan to northern Australia, and is closely related to, if not identical with, the Caribbean species E. fisiforme (C. Agardh) J. Agardh (Cheney 1988). Other species occur in southern Japan, China, the Philippines, Indonesia, eastern and western Australia, Mauritius, east Africa, and the Gulf of California.

Numbers of names and species: There are 56 species (and infraspecific) names in the database at present, of which 28 have 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):

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: http://www.algaebase.org/search/genus/detail/?genus_id=35110

Citing AlgaeBase
Cite this record as:
Guiry, M.D. & Guiry, G.M. 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 20 May 2013.

Algaebase taxon LSID: urn:lsid:algaebase.org:taxname:8128