Gracilaria, 1830, nom. et typ. cons.
Lectotype species: Gracilaria compressa (C.Agardh) Greville
Currently accepted name for the type species: Gracilaria bursa-pastoris (S.G.Gmelin) P.C.Silva
Original publication:Greville, R.K. (1830). Algae britannicae, or descriptions of the marine and other inarticulated plants of the British islands, belonging to the order Algae; with plates illustrative of the genera. pp. [i*-iii*], [i]-lxxxviii, -218, pl. 1-19. Edinburgh & London: McLachlan & Stewart; Baldwin & Cradock.
Type designated in Steentoft, M., Irvine, L.M. & Bird, C.J. (1991). Proposal to conserve the type of Gracilaria, nom. cons., as G. compressa and its lectotypification (Rhodophyta: Gracilariaceae). Taxon 40: 663-666.
Taxonomic status: currently recognized as a distinct genus.
Gender: This genus name is currently treated as feminine.
Most recent taxonomic treatment adopted: Steentoft, M., Irvine, L.M. & Bird, C.J. (1991). Proposal to conserve the type of Gracilaria, nom. cons., as G. compressa and its lectotypification (Rhodophyta: Gracilariaceae). Taxon 40: 663-666.
Description: Plants of the largest species can reach 60 cm in length. Thalli range from erect to prostrate and from terete to broadly flattened. Some species form articulated fronds composed of cylindrical or irregularly shaped units. The apical structure of the type species has been demonstrated by Kling & Bodard (1986) to be uniaxial, although too compact to be easily interpreted. Procarps, fusion-cell formation, and early gonimoblast development are typical of the family. In most species, nutrient tubular cells connect the gonimoblast to cells of the inner pericarp. Carposporangia occur in chains, and cystocarps are strongly protuberant. Spermatangia have been reported to form in one of 3 taxonomically important patterns (Bird and McLachlan 1984), either as a completely superficial continuum or in sori flush with the outer cortex ("Chorda"-type), in shallow sunken patches ("Textorii"-type), or in deep conceptacular pits ("Verrucosa"-type). Fredericq and Hommersand (1989b) have advocated removal of species with the "Chorda"-type spermatangia to the genus Gracilariopsis (see below). Tetrasporangia are mostly decussate-cruciate and occur both scattered and in nemathecia, according to the species.
Information contributed by: G.T. Kraft. The most recent alteration to this page was made on 20 Jan 2017 by M.D. Guiry.
Comments: Members of the genus are highly prized, both as direct foodstuffs (Abbott, 1985) and for their agar content. McLachlan and Bird (1986) review prior work on the biology and productivity of the genus, based largely on their detailed studies of the major northwest Atlantic species, which Guiry and Freamhainn (1985) demonstrate by interfertility studies to be specifically distinct from a superficially similar eastern Atlantic species. Much work has been directed to the field (Simsonetti et al. 1970) and tank cultivation (e.g. Edelstein 1977), genetics (largely by van der Meer and colleagues, e.g. van der Meer ), genetic improvement (Patwary and van der Meer (1983); van der Meer and Patwary 1983), and taxonomy (e.g., Yamanoto 1978; Bird and McLachlan 1982; Reading and Schneider 1986; Bird and Oliveira F. 1986; Nelson 1987) of the genus. Taxonomists are united in stressing the difficulties in identifying and characterizing many of the described species on anatomical features alone. Bird et al. (1987) employ pyrolysis-capillary gas chromatography to differentiate between the polysaccharide content of superficially similar species, providing a potentially objective method for establishing species identifications of even herbarium material. Another promising solution to problems of identifying undetermined species of Gracilaria is the use of plastid DNA restriction endonuclease patterns, which Goff and Coleman (1988) found to be identical within species but different between them. Distribution: The type species, originally described from England, has long been considered to be nearly cosmopolitan in cool- to warm-temperate seas. Recent comparative studies, however, indicate that several species may be involved in the G. verrucosa complex (Bird et al. 1982), particularly in the western Pacific (Abbott et al. 1985). The genus is most abundant in regions where mean water temperatures are 25 deg. C or more, with numbers falling off rapidly where 3-month mean minimum temperatures occur (McLachlan and Bird 1984). Over 150 species have been described, many of them poorly known and with very limited distributions. Some species long considered to be widely distributed, on the other hand, appear to be complexes of distinct taxa difficult to separate on habit differences alone.
Numbers of names and species: There are 282 species names in the database at present, as well as 54 infraspecific names. Of the species names, 188 have been flagged as accepted taxonomically on the basis of the listed literature under the species name. In some instances, opinions on taxonomic validity differ from author to author and users are encouraged to form their own opinion. AlgaeBase is a work in progress and should not be regarded as a definitive source only as a guide to the literature..
Names: ('C' indicates a name that is 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):
Click here to also show infraspecific names in the list below.
Verification of data
Users are responsible for verifying the accuracy of information before use, as noted on the website Content page.
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.
Created: 01 January 2001 by M.D. Guiry
Verified by: 20 January 2017 by M.D. Guiry
Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=14
Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2018. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 22 October 2018.