Dictyurus Bory de Saint-Vincent, 1834

Holotype species: Dictyurus purpurascens Bory

Original publication and holotype designation: Bélanger, C. & Bory de Saint-Vincent, J.B.G.M. (1834). Voyage aux Indes-Orientales. Botanique IIe Partie. Cryptogamie. pp. 1-192. Paris: A. Bertrand.

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Description: Thallus erect from decumbent axes, sympodially developed and radially branched, the upper portions appearing leafy or plumose due to sac-like networks of determinate pseudolaterals. Indeterminate axes terete or slightly compressed and alternately and distichously producing determinate pseudolateral branch systems from every other polysiphonous segment. Pseudolaterals pigmented, polysiphonous basally and centrally, monosiphonous elsewhere, at first subdichotomously, then alternately and distichously branched, ultimately developing as secondary sympodia, with maturity and growth of connective cells becoming interlinked, spirally disposed networks surrounding the axes. Network margins beset with short spur-like branches. Networks in total making the axes appear angular, fan-shaped or terete, these often becoming deciduous below, after which adventitious indeterminate branches can develop. Axial cells of indeterminate axes surrounded by 4 periaxials which are quickly enclosed by descending rhizoidal filaments, collectively forming a thick cortex. Dioecious, spermatangia formed on several successive monosiphonous side branches of terminal polysiphonous portions of lateral networks. Successive cells of the monosiphonous spermatangial branches enclosed by spermantangia, overall appearing as simple or branched sori with sterile monosiphonous tips extended and fused into an enclosing network, the entire structure (arrhenophore) external to the lateral vegetative network. After the first generation of spermatangial branches matures, a second is produced from newly developed monosiphonous branches off central polysiphonous axes of arrhenophores. Procarps formed on the tips of polysiphonous axes at the outer edge of lateral networks, several per tip, each consisting of a 4-celled carpogonial branch and 2 sterile groups of cells borne on the supporting cell. Procarps enclosed by pericarps before fertilization. After fertilization, carpogonium cuts off a connecting cell which fuses with the central cell of the carpogonial branch and then auxiliary cell just cut off the supporting cell. The fusion cell generates monopodial gonimoblast filaments with terminal carposporangia. Carposporophytes connected to large, corticated pericarps by sterile connecting filaments, these cystocarps external to the network. Tetrahedral sporangia produced in successive whorls, forming simple or branched, lanceolate stichidia in clusters on terminal portions of polysiphonous axes, thus extended beyond lateral networks. Tetrasporangia completely enclosed by cover cells at maturity.

Information contributed by: C.W. Schneider. The most recent alteration to this page was made on 2010-10-06 by M.D. Guiry.

Taxonomic status: This name is of an entity that is currently accepted taxonomically.

Most recent taxonomic treatment adopted: Schneider, C.W. & Wynne, M.J. (2007). A synoptic review of the classification of red algal genera a half a century after Kylin's "Die Gattungen der Rhodophyceen". Botanica Marina 50: 197-249.

Comments: Uncommon in tropical and subtropical seas worldwide, mostly subtidal.

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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=35482

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 06 October 2010. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 27 November 2024