Spirogyra Link, 1820, nom. cons.
Lectotype species: Spirogyra porticalis (O.F.Müller) Dumortier
Original publication: Nees, C.G. (1820). Horae physicae Berolinenses collectae ex symbolis virorum doctorum H. Linkii...; edicuravit Christianus Godof. Nees ab Esenbeck.. pp. [i-xii], 1-123, , 27 pls. Bonnae [Bonn]: Sumtibus Adolphi Marcus.
Type designated in: Silva, P.C. (1952). A review of nomenclatural conservation in the algae from the point of view of the type method. University of California Publications in Botany 25: 241-323.
Description: Thalli comprised of unbranched uniseriate filaments intertwined to form skeins. Cells cylindrical, 10 to >200 µm in diameter, most 20 to 60 µm, up to several times as long; cell wall two-layered with inner cellulose, outer mucilage layer that makes filaments very slimy to touch; end walls plane; no flagellated stages. Basal cells infrequently with rhizoidal holdfasts. End walls with several layers: outer mucilaginous, inner cellulose; flat (plane) in 75% of species or cup-like infolding (replicate) in 25%; cells of replicate species narrower than plane species. Cells may contain crystalline inclusions including aragonite. Cells uninucleate; chloroplasts from 1-15 per cell, number uniform in cells within filament; plastids ribbonlike, coiled, pressed against cell wall within parietal layer of cytoplasm, edges ruffled, and many disc-shaped pyrenoids. Cytoplasmic strands support centrally located nucleus within central vacuole. Chromosomes (n=3 to 84) mostly dotlike (<1.5 µm), rarely rodlike (>4 µm). Nucleolar organizing chromosomes with satellites often conspicuous at anaphase. Akinetes, and aplanospores common; parthenospores less so. Sexual reproduction by conjugation, typically in late spring and summer, mostly scalariform: parallel filaments align, outgrowths (papillae) from cells of one or both filaments in pair fuse to form conjugation tubes; series of tubes along filaments forms ladderlike structure. Protoplasts of adjacent cells contract, become nonflagellated gametes. Typically male gamete moves in amoeboid fashion through tube to fuse with the female; gametes thus morphologicallly identical, physiologically anisogamous gametes; male and female gametes may form in cells of either filament (cross conjugation). Lateral conjugation occurs in some species adjacent cells in same filament joined by curved conjugation tube. Conjugation usually homothallic (between filaments from same clonal culture); heterothallic (interclonal) conjugation reported, frequency in nature unknown. Life cycle haplobiontic; meiosis zygotic; three of four haploid nuclei disintegrate and single germling emerges. Chloroplast from male gamete disintegrates, maternal plastid persists. Zygospores yellow to brown, most often ellipsoid, but some ovoid, lenticular, or spherical. Zygospores with three wall layers: exospore (outer), mesospore (middle), and endospore (inner); mesospore smooth or variously ornamented, crucial to species identification. Exo- and endospores walls cellulose, gelatinous, or both; mesospore wall contains sporopollenin.
Information contributed by: R.M. McCourt & R.W. Howshaw. The most recent alteration to this page was made on 2015-10-19 by M.D. Guiry.
Taxonomic status: This name is of an entity that is currently accepted taxonomically.
Most recent taxonomic treatment adopted: Guiry, M.D. (2013). Taxonomy and nomenclature of the Conjugatophyceae (=Zygnematophyceae). Algae. An International Journal of Algal Research 28: 1-29.
Comments: Widespread in freshwater habitats; reported from all continents; tropical to arctic climates. Filaments annual, with burst of growth in spring. Filaments usually found as free-floating masses, also frequently attached to substrate. Habitats include ponds, slow-moving streams, backwaters, roadside ditches, swift-flowing rivers. Occurs frequently in stagnant but aerobic habitats, in floating or submerged mats. Competition with other algae reported. Primary producer but role in food chain largely unstudied; preyed upon by herbivirous fish, fungi, and protozoans. No major economic use. Occasional blooms reported, and may be nuisance weed in water supplies. Widely used in experimental studies: role of dictyosome vesicles in formation of cell walls and external mucilage sheath; chloroplast growth and coiling responses under microbeam illumination; role of phytochrome in rhizoid differentiation. Filaments show endogenous rhythmic movements in response to varying light intensities. Fossil zygospores of Spirogyra and other Zygnemataceae common, oldest from Carboniferous (>300 million years b.p.). Zygospores used in paleoecological studies as markers for clean, oxygen-rich, shallow stagnant, mesotrophic water in habitats subject to seasonal warming. Some species tolerate high heavy-metal concentrations. Polyploidy occurs within clonal lineages in laboratory and mostly likely in nature; ploidal change correlates with marked changes in quantitative morphological features, e.g., cell width, which is used to distinguish species. Thus, several ploidal levels in clonal culture or in field collection may appear as an assemblage of several species. Some of large number (>400) described species may be recent polyploids. Phylogenetic relationships to other conjugating green algae in Zygnematales (Mesotaeniaceae and Desmidiaceae) uncertain; conflicting phylogenetic hypotheses have postulated relation to other taxa with ribbonlike chloroplasts, either unicells (Spirotaenia) or filaments. Analysis of chloroplast DNA suggests close relationship with Sirogonium. Discovery of primitive phragmoplast, biochemical similarities, and gene-sequence data from ribosomal DNA and chloroplast DNA suggest close relationship with other Charophyceae and lower land plants.
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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=43564
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 19 October 2015. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 14 August 2022