Microdictyon Decaisne, 1841

Holotype species: Microdictyon agardhianum Decaisne

Currently accepted name for the type species: Microdictyon tenuius J.E.Gray

Original publication and holotype designation: Decaisne, J. (1841). Plantes de l'Arabie Heureuse, recueillies par M. P.-E. Botta et décrites par M. J. Decaisne. Archives du Muséum d'Histoire Naturelle, Paris 2(2): 89-199, pls V-VII.

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Description: Thallus composed of one or more complanate, monostromatic, reticulate blades, 2-10 cm tall. Plants astipitate. Annular constrictions not present. Apical orientation and symmetry secondarily lost in some species. Reticulum composed of branched, septate, filiform cells, 50-800 µm diameter, 50-1000 µm long; coarse or delicate; loosely or tightly woven. Branching opposite or stellate. Venation patterns prominent in some species. Intercalary septations, not associated with branching, common. Rhizoid well developed from which new uprights can arise. Adventitious rhizoids common, arising at basal poles of older cells. Structural reinforcement of reticulum by unspecialized, indeterminate tenacular cells. Cell division by centripetal invagination. Cell multinucleate; chloroplasts numerous per cell and discoid with single pyrenoid surrounded by starch sheath and bisected by traversing thylakoid. Life history consists of biphasic alternation of isomorphic generations involving quadriflagellate zoospores and isogamous, biflagellate gametes. M. tenuis with diploid chromosome number of 36. Nuclear DNA estimated at 2.0, 3.8 and 8.6 pg (1C, 2C, 4C) for M. marinum. Microdictyon is widely distributed throughout the tropics and subtropics in subtidal reef flat habitats. The genus may also be found in deep-water habitats >10 m. In quiet waters the plants can become heavily epiphytized and deep water the thalli can become very large, > 10 cm. Ultrastructural studies of chloroplasts and flagellar apparatus carried out. Microdictyon is best known through the taxonomic studies of Setchell and Egerod. The phylogenetic position of the genus within the Siphonocladales-Cladophorales complex partly resolved. Anadyome is the sister-group of Microdictyon based on immunological data, character compatibility analyses and nuclear encoded rRNA sequence data.

Information contributed by: J.L. Olsen. The most recent alteration to this page was made on 2018-02-14 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 neuter.

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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: https://www.algaebase.org/search/genus/detail/?genus_id=33605

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 14 February 2018. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 16 April 2024