Cladostephus C.Agardh, 1817

Lectotype species: Cladostephus spongiosus (Hudson) C.Agardh

Original publication: Agardh, C.A. (1817). Synopsis algarum Scandinaviae, adjecta dispositione universali algarum. pp. [i]-xl, [1]-135. Lundae [Lund]: Ex officina Berlingiana.

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Type designated in: Bonnemaison, T. (1822). Essai d'une classification des hydrophites loculées, ou plantes marines articulées qui croissent en France. Journal de Physique, de Chimie, d'Histoire Naturelle et des Arts 94: 138-148; 174-203.

Description: Plants forming 5-25 (-40) cm tall, yellowish brown to dark brown or olivaceous, epilithic, erect, spreading bushes or isolated groups of (1-) 2-5 heterotrichous axes. Basal parts consisting of small or extensive, polystromatic, crustose discs. Axes and indeterminate laterals long and prominent, erect, terete, auxocaulous, brown or blackish, with smooth surface, more or less wiry. Branching of several orders, in indeterminate axes hemiblastic and pseudodichotomous; determinate laterals in whorls, densely crowded or distinctly verticillate, stiff, divaricate, straight or upwardly curved, unbranched or scarcely acroheteroblastically branched. Occasionally a lenticular branch initial is formed from the conspicuous cylindrical apical cell of the determinate laterals before a segment is cut off. Segments each divide transversely once before frequent longitudinal and transverse segmentation and secondary growth. Internal structure of axes consisting of cubical medullary cells, a pseudoparenchymatous inner cortex of enlarging cells and in older parts a small-celled outer cortex, formed by appressed rhizoids. Loose descending rhizoids absent. Hairs in clusters in axils of small laterals of branched determinate laterals. Pericysts occasional, in young segments of indeterminate axes. Reproductive structures: pedicellate plurilocular isogametangia and pedicellate unilocular zoidangia borne laterally on crowded, meriblastic, fertile, determinate laterals, which arise from the axes. Cosmopolitan marine in the tidal zone and in sublittoral, restricted to temperate regions. Unattached forms occur occasionally in seagrass meadows. These sterile forms with only few laterals in each worl propagate only by fragmentation. The diplohaplontic life history is isomorphic, isogamic and probably monoecious. Parthenogenesis as well as ephobogenesis has been observed. Basal chromosome number not known.

Information contributed by: Prud'homme van Reine. The most recent alteration to this page was made on 2020-06-24 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 masculine.

Most recent taxonomic treatment adopted: Heesch, S., Rindi, F., Guiry, M.D. & Nelson, W.A. (2020). Molecular phylogeny and taxonomic reassessment of the genus Cladostephus (Sphacelariales, Phaeophyceae). European Journal of Phycology 55(4): [1-18] 426-443.

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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. 24 June 2020. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 16 July 2024

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