Splachnidium Greville, 1830

Holotype species: Splachnidium rugosum (Linnaeus) Greville

Original publication and holotype designation: Greville, R.K. (1830). Algae britannicae, or descriptions of the marine and other inarticulated plants of the British islands, belonging to the order Algae; with plates illustrative of the genera. pp. [i]-lxxxviii, [1]-218, pl. 1-19. Edinburgh & London: McLachlan & Stewart; Baldwin & Cradock.

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Description: Thallus terete, irregularly branched to 20 cm long and 8 mm diameter. Growth from an apical meristem consisting of a pear-shaped apical cell and surrounding tissue, densely covered with short hairs. Thallus structure is parenchymatous and differentiated into a compact outer layer of small cells grading into a larger-celled cortex and a medulla of loose filaments surrounding copious deposits of mucilage. Stellate chloroplasts possess an axial pyrenoid penetrated by cytoplasmic channels. Conceptacles develop from pear-shaped initial cells which differentiate within the apical meristem. Phaeophycean hairs develop in conceptacles. Life history is haplodiplontic. Macrothalli are sporophytes producing ovoid unilocular meiosporangia, 169-200 ( 65-90 fm, in conceptacles scattered over the thallus. Meiospores are heterokont, positively phototactic, 13-14 fm long, and develop into dioecious filamentous gametophytes. Sexual reproduction is anisogamous. Plurilocular gametangia are conical, 130-150 ( 45-60 fm. Male gametangia are orange and have smaller loculi than the female gametangia which are dark brown in color. Gametes are heterokont and possess an eyespot. Male gametes are 4-6 fm long; females are 7-10 fm and have a larger chloroplast. In culture, unfertilized female gametes develop parthenogenetically, and haploid macrothalli occasionally develop directly on gametophytes. Splachnidium grows intertidally in cold temperate regions of Australia, New Zealand, South Africa, Juan Fernandez Island and on some subantarctic islands. There is doubt over the most appropriate ordinal classification of Splachnidium. Though classified in the Chordariales by Womersley (1987), I consider that the highly unusual chloroplast structure, and the unique apical meristem clearly distinguish Splachnidium apart from other species in this order. The affinities of Scytothamnus possibly lie with other taxa sharing a similar chloroplast structure, Splachnidium and Stereocladon.

Information contributed by: M. N. Clayton. The most recent alteration to this page was made on 2014-06-21 by M.D. Guiry.

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=40695

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 21 June 2014. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 22 November 2024