Giraudia Derbès & Solier, 1851

Holotype species: Giraudia sphacelarioides Derbès & Solier

Original publication and holotype designation: Castagne, L. (1851). Supplément au catalogue des plantes qui croissent naturellement aux environs de Marseille. pp. [1]-125, pls VIII-XI. Aix: Imprimerie de Nicot & Pardigon, sur le Cours.

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Description: Plants composed of monostromatic disc of radiating filaments, uniseriate medullary filaments in a pulvinate aggregation, and parenchymatous erect thalli which issue on them, yellowish to medium brown. Uniseriate medullary filaments are at times absent. Erect thalli terete, polystichous, attenuated at the base and tapering in upper part, simple or sparsely branched above, with uniseriate meristematic region at the base. Each cells contains many discoid chloroplast with pyrenoid. Phaeophycean hairs present. Plurilocular sporangia transformed from the surface cells, in sori or as discrete individual uniseriate or ectocarpoid sporangia. Unilocular sporangia reported in G. robusta, elongate ovoid. Life history asexual, direct. Sauvageau (1927) cultured plurispores from sporangia on micro- and macrothalli of Mediterranean G. sphacelarioides, and reported direct formation of erect thallus in both of them. Skinner and Womersley (1984) cultured Australian G. sphacelarioides. The plurispores from intercalary and lateral plurilocular sporangia settled and germinated in stellate or filamentous manner and developed into myrionimatoid microthalli which directly produced erect thalli bearing plurilocular sporangia. Ascocyclus-like microthallus was also observed in culture.

Information contributed by: H. Kawai. The most recent alteration to this page was made on 2020-03-29 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 feminine.

Most recent taxonomic treatment adopted: Silberfeld, T., Rousseau, F. & Reviers, B. de (2014). An updated classification of brown algae (Ochrophyta, Phaeophyceae). Cryptogamie Algologie 35(2): 117-156, 1 fig., 1 table.

Comments: Common epiphyte on Posidonia and other sea grasses. Known from Mediterranean and Australian coast.

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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in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. 29 March 2020. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 21 May 2024

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