Scytothamnus Hooker f. & Harvey, 1845

Holotype species: Scytothamnus australis (J.Agardh) Hooker f. & Harvey

Original publication and holotype designation: Hooker, [J.D.] & Harvey, W.H. (1845). Algae Novae Zelandiae; being a catalogue of all of the species of algae yet recorded as inhabiting the shores of New Zealand, with characters and brief descriptions of the new species discovered during the voyage of H.M. discovery ships "Erebus" and "Terror" and of others communicated to Sir W. Hooker by Dr. Sinclair, the Rev. Colenso, and M. Raoul. London Journal of Botany 4: 521-551.

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Description: Thallus terete, irregularly densely branched to 30 cm long and 3 mm diameter. Growth from a small group of apical cells. Thallus structure is parenchymatous and differentiated into a compact outer layer of small cells containing numerous physodes, a cortex of isodiametric cells cells and a medulla of loose filaments surrounded by mucilage. Stellate chloroplasts possess an axial pyrenoid penetrated by cytoplasmic channels. Phaeophycean hairs develop in cryptpostomata. Life history is haplodiplontic. Macrothalli are sporophytes producing ovoid to globose unilocular meiosporangia sunk amongst the surface layer of cells. Meiospores are heterokont, and develop into dioecious filamentous gametophytes. Sexual reproduction is isogamous. Plurilocular gametangia are multiseriate and form clusters. Gametes are heterokont, to 6 fm diameter and have an eyespot. Zygotes develop into diploid sporophytes. In culture, unfertilised gametes develop parthenogenetically and haploid macrothalli may develop directly on gametophytes. Scytothamnus grows intertidally in cold temperate and subantarctic regions of the southern hemisphere. It has also been recorded from the west coast of Canada. There is doubt over the most appropriate ordinal classification of Scytothamnus. Though classified in the Chordariales by Womersley (1987), I consider that the highly unusual chloroplast structure, the mode of growth and the presence of intercalary longitudinal divisions set Scytothamnus apart from this order. On the basis of these characters the affinities of Scytothamnus possibly lie with Splachnidium and Stereocladon. A possible third species recorded from the Falkland Islands requires further investigation.

Information contributed by: M. N. Clayton. The most recent alteration to this page was made on 2021-10-10 by E.A. Molinari Novoa.

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

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.

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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=42570

Citing AlgaeBase
Cite this record as:
E.A. Molinari Novoa in Guiry, M.D. & Guiry, G.M. 10 October 2021. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 22 November 2024