Jania J.V.Lamouroux, 1812: 186

Classification:
Empire Eukaryota
Kingdom Plantae
Phylum Rhodophyta
Subphylum Eurhodophytina
Class Florideophyceae
Subclass Corallinophycidae
Order Corallinales
Family Corallinaceae
Subfamily Corallinoideae
Tribe Janieae

Lectotype species: Jania rubens (Linnaeus) J.V.Lamouroux

Original publication:Lamouroux, [J.V.F.] (1812). Extrait d'un mémoire sur la classification des Polypiers coralligènes non entièrement pierreux. Nouveaux Bulletin des Sciences, par la Société Philomathique de Paris 3: 181-188.
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Type designated inManza, A.V. (1937). The genera of the articulated corallines. Proceedings of the National Academy of Science of the United States of America 23: 44-48.
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Taxonomic status: currently recognized as a distinct genus.

Description: Thalli comprising crustose bases of limited size, often replaced by stolons, and dichotomously branched fronds; pinnae present in at least one variety (J. rubens var. corniculata). Fronds of terete or subterete calcified intergenicula separated by uncalcified genicula; a few species with flattened intergenicula. Intergenicula of one to several arching tiers of medullary cells surrounded by a photosynthetic cortex and a unistratose layer of epithallial cells. Cells in contiguous filaments often fusing laterally; secondary pit-connections lacking. Genicula consisting of single tiers of long, straight, unbranched cells uncalcified except where they project into neighboring intergenicula. Trichocytes present, but often not evident; trichocyte bases elongate in surface view, pores often excentric. Reproductive cells forming within conceptacles originating in medullary meristems at branch apices in line with intergenicular axes (axial conceptacles). At maturity, a single swollen conceptacle terminating each fertile intergeniculum. Conceptacle pores central. Surmounting branches present in tetrasporangial and carposporangial conceptacles, sometimes in concatenate series. Tetrasporangial conceptacles containing <10 mature tetrasporangia prior to spore discharge. Sporangial initials dividing into young sporangia and stalk cells, sporangia subsequently enlarging, nuclei dividing meiotically, and simultaneous cytokineses yielding zonate tetrasporangia. Sexual plants dioecious or, in at least one species, monoecious. Spermatangial conceptacles lanceolate with high walls coated with basal cells and spermatangial mother cells. Carpogonial conceptacles with supporting cells and carpogonial filaments, each with a single carpogonium and, when receptive, an elongate trichogyne. Each carposporangial conceptacle containing a narrow, thick fusion cell with gonimoblast filaments arising from its edges. Spores germinating into sporelings producing one to several fronds. In some species young fronds readily detached and becoming entangled in the branches of other seaweeds where they continue to grow and become attached by stolons.

EMENDED DESCRIPTION: Primary crustose bases reduced or replaced by stolons; main branching dichotomous; intergenicular medullary cells 90-130 µm long; genicular cells longer in the center than at the periphery; conceptacle primordia medullary in origin; carposporophytic fusion cell up to 35 µm thick and less than 130 µm broad with convex upper surface; male conceptacles long and narrow, chambers 90-250 µm broad, canal less than 120 microns long; tetrasporangial conceptacles containing less than 15 mature spornagia per conceptacle; sporeling development rapid, occasionally semiendophytic Choreonema thuretii present. (Kim et al., 2007: 1317).

Comments: Common as epiphytic or epilithic tufts, or forming turfs in tropical, subtropical, and warm temperate areas. Fronds of most species probably growing rapidly and with lifespans of less than one year. Compared to Corallina, tetraspores (of J. rubens) secrete more mucilage, become attached more quickly, and produce sporelings with articulated fronds sooner (in 8 days) from limited holdfasts. Culture experiments have shown that lowering the phosphate concentration in media enhances growth (phosphate is a crystal inhibitor of calcite). Chromosome studies yield n = 24 (J. rubens). Jania is in the tribe Janieae together with Haliptilon and Cheilosporum. The tribe is clearly delimited from the Corallineae on the basis of reproductive cells and conceptacle structure

NCBI Nucleotide Sequences

Numbers of names and species: There are 115 species (and infraspecific) names in the database at present, of which 47 have been flagged as currently accepted taxonomically.

Names: ('C' indicates a name that is currently 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):

References
Wynne, M.J. & Schneider, C.W. (2010). Addendum to the synoptic review of red algal genera. Botanica Marina 53: 291-299.

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: http://www.algaebase.org/search/genus/detail/?genus_id=94

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 19 June 2013.

Algaebase taxon LSID: urn:lsid:algaebase.org:taxname:8806