Cladophora Kützing, 1843: 262

Classification:
Empire Eukaryota
Kingdom Plantae
Subkingdom Viridaeplantae
Phylum Chlorophyta
Class Ulvophyceae
Order Cladophorales
Family Cladophoraceae

Lectotype species: Cladophora aegagropila (Linnaeus) Trevisan

Original publication: Kützing, F.T. (1843). Phycologia generalis oder Anatomie, Physiologie und Systemkunde der Tange... Mit 80 farbig gedruckten Tafeln, gezeichnet und gravirt vom Verfasser. pp. [part 1]: [i]-xxxii, [1]-142 , [part 2:] 143-458, 1, err.], pls 1-80. Leipzig: F.A. Brockhaus.
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Taxonomic status: currently recognized as a distinct genus.

Description: Thalli of uniseriate branched filaments with apical and/or intercalary growth. Branches sparse to profuse with branches inserted laterally below apex of cell or apically on cell (a pseudodichotomy). If attached, branching rhizoids arise from basal cell and other cells in basal region, or simple discoid holdfast produced. Chloroplasts parietal, either densely packed discoid and/or united in a reticulum. Pyrenoids in many chloroplasts, bilenticular, flanked by two bowl-shaped starch bodies. Cells multinucleate, nuclei dividing more or less synchronously with nuclear membrane remaining intact. Cell wall polysaccharide mainly crystalline cellulose I, forming numerous lamellae of microfibrils in crossed fibrillar pattern. Asexual reproduction by biflagellate or quadriflagellate zoospores only method of reproduction in some species, some species only reproducing by thallus fragmentation. Akinetes produces by most species under unfavourable conditions, these swollen, thick-walled, filled with starch. Thick walled rhizoids and basal portions of main axes also perennating devices. Sexual reproduction by regular alternation of generations producing biflagellate isogametes and quadriflagellate zoospores. Meiosis precedes spore production. Zoidangia with 1-3 pores, cruciate zooids released under pressure. Zoids of C. rupestris with well developed layer of granules outside the plasmalemma and inside the 'fibrous-layer' which may be involved in cell wall synthesis.

Comments: Cladophora cosmopolitan in temperate and tropical regions, occurring in freshwater, brackish and marine conditions. The various species are found intertidally in wave-exposed to very sheltered habitats, in brackish pools, lagoons and mudflats, and in more or less eutrophic freshwater streams and lakes with pH > 7. Certain unattached species can be aggregated into spherical mats, 2-10 cm in diameter, called "Cladophora Balls". Cladophora glomerata can be a rapid colonizer of rocky stream beds and at temperatures > 15 1/2 C readily produces zoospores and new vegetative growth following winter dormancy or severe floods. At extreme temperatures, freshwater Cladophora can have reduced salinity-tolerance range, but measured tolerances to temperature and salinity exceed ranges experienced in natural environment. One-time exposures to a 12 h or more daylight period lead to a reduction in biomass of riverine C. glomerata. Cell walls of the freshwater species C. glomerata include silica, an essential nutrient for this species. Calcium is also an essential element and CaCO3 depositions occur in older cells. In sea-water, Cladophora normally absorbs bicarbonate rather than CO2 for photosynthesis, and has a CO2 compensation point of 8-12 ul.l-1. Cladophora divided into at least 14 sections, three of which have been treated as distinct genera (as Willeela, Basicladia, Rama). According to van den Hoek (1982, p. 30) most genera in Cladophorales represent "further specializations of thallus architectures realised in certain Cladophora sections," and the circumscription of Cladophora does not fully exclude them. A practical and meaningful generic framework within Cladophorales has yet to be found. Genome divergence in transatlantic C. albida populations is higher than that observed in most other eukaryotes they are presumed to have diverged ca. 12 million years ago. In most species chromosome number is n=12, but polyploidy common in freshwater species (morphologically distinct thalli of C. rivularis can be related to different ploidy levels). Chloropteris Montagne is a pinnately branched plant originally referred to Cladophora section Aegagrophila (as C. leprieurii Kützing), and is possibly a synonym of Cladophora. Lychaete J. Agardh and Anadema J. Agardh were referred to Cladophora by De Toni (1899) and Wille (1897), respectively. Several species of Lychaete subsequently published by J. Agardh are now referred to Chaetomorpha but the South African type apparently belongs to Cladophora. According to Bourrelly (1966), Chaetocladiella Meyer et Skabitschevskii resembles Basiocladia but is not epizoic. This genus of 3 species in therefore tentatively included as a synonymn of Cladophora sensu van den Hoek.

NCBI Nucleotide Sequences
As of 2 June 2009, nucleotide sequence data are available at http://www.ncbi.nlm.nih.gov/Genbank for 141 samples identified as Cladophora. Taxonomic identifications of these samples to genus (or species) levels unaccompanied by explicit indication of voucher specimens may not be verifiable on morphological/anatomical grounds and consequently be of little or no taxonomic value, as noted by Harvey et al. 2009.

Numbers of names and species: There are 1056 species names in the database at present, of which 176 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):

References
John, D.M. (2002). Order Cladophorales (=Siphonocladales). In: The Freshwater Algal Flora of the British Isles. An identification guide to freshwater and terrestrial algae. (John, D.M., Whitton, B.A. & Brook, A.J. Eds), pp. 468-470. Cambridge: Cambridge University Press.

Information contributed by: T.J. Entwisle. The most recent alteration to this page was made on 12 Nov 2005 by M.D. Guiry.

Contributors
Many 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 and intended to be published in CD format. The descriptions are being continually updated, however, and each current contributor is identified above. The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and of Dr Parker.