153,798 species and infraspecific names are in the database, 21,012 images, 59,568 bibliographic items, 413,155 distributional records.

Rissoella J.Agardh, 1849

Classification:
Empire Eukaryota
Kingdom Plantae
Subkingdom Biliphyta
Phylum Rhodophyta
Subphylum Eurhodophytina
Class Florideophyceae
Subclass Rhodymeniophycidae
Order Gigartinales
Family Rissoellaceae

Lectotype species: Rissoella verruculosa (Bertoloni) J.Agardh

Original publication:Agardh, J.G. (1849). Algolosgiska bidrag. Öfversigt af Kongl. Vetenskaps-Adademiens Förhandlingar, Stockholm 6: 79-89.

Type designated in Schmitz, F. (1889). Systematische Übersicht der bisher bekannten Gattungen der Florideen. Flora oder Allgemeine botanische Zeitung 72: 435-456, pl. XXI.
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Taxonomic status: currently recognized as a distinct genus.

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.

Nomenclatural notes
Two names were originally included by J. Agardh (1849: 85): "Species sunt: Fucus verruculosus Bertol. et forsan Grateloup. denticulata Mont Voy Bonit." However, no combinations were made until J.Agardh (1851: 241). - (23 Jan 2017) - M.D. Guiry

Description: Plants reach 10-20 cm in height, are erect from discoid holdfasts, and consist of flattened, linear, sometimes spirally twisted fronds fringed with marginal teeth and processes. Cystocarps and tetrasporangia scattered over the frond surfaces. Mollion et al. (1986) analyzed the carrageenans and found that most are a new type, which they named "omega" carrageenan. The RISSOELLACEAE is a monospecific family restricted to the Mediterranean Sea. Plants are multiaxial and composed of a filamentous medulla surrounded by a pseudoparenchymatous inner cortex of apparently secondarily pit-connected cells. Carpogonial branches are 2-3-celled, the basal cell capable of bearing a sterile lateral branch. Carpogonial branches are directed laterally or inwardly and have reflexed trichogynes. Aggregations of carpogonial branches occur in the inner cortex in association with a single prominent auxiliary cell and numerous cortical cells that give rise to short, branched files of nutritive cells. Early gonimoblasts develop thallus inwardly, the mataure cystocarp being composed of a richly branched central fusion cell bearing chains of cells nearly all of which become carposporangia, the carposporophyte jacketed by a thick ostiolate pericarp lacking an inner filamentous hull. Spermatangia are located in cortical pits surrounded by paraphyses. They bud off acropetally, the closest similarities being to Harveyella mirabilis and certain spore types of fungi, according to Schotter (1964). Tetrasporophytes are isomorphic with gametophytes and produce terminally attached zonate tetrasporangia in thge outer cortex, the sporangia being borne on l-2-celled stalks.

Information contributed by: G.T. Kraft. The most recent alteration to this page was made on 23 Jan 2017 by M.D. Guiry.

Comments: Distribution: Endemic to the Mediterranean Sea, generally in mid-littoral rocky habitats (Furnari 1985).

Numbers of names and species: There are 2 species names in the database at present, of which 1 has been flagged as accepted taxonomically on the basis of the listed literature under the species name. In some instances, opinions on taxonomic validity differ from author to author and users are encouraged to form their own opinion. AlgaeBase is a work in progress and should not be regarded as a definitive source only as a guide to the literature..

Names: ('C' indicates a name that is accepted taxonomically; 'S' a homotypic or heterotypic synonym; 'U' indicates a name of uncertain taxonomic status, but which has been subjected to some verification nomenclaturally; 'P' indicates a preliminary AlgaeBase entry that has not been subjected to any kind of verification. For more information on a species click on it to activate a link to the Species database):

Click here to also show infraspecific names in the list below.

Verification of data
Users are responsible for verifying the accuracy of information before use, as noted on the website Content page.

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.

Created: 28 December 2000 by M.D. Guiry

Verified by: 23 January 2017 by M.D. Guiry

Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=38737

Citing AlgaeBase
Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2018. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 11 December 2018.

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