152,947 species and infraspecific names are in the database, 20,947 images, 59,170 bibliographic items, 408,277 distributional records.

Boreolithon A.S.Harvey & Woelkerling, 1995

Classification:
Empire Eukaryota
Kingdom Plantae
Subkingdom Biliphyta
Phylum Rhodophyta
Subphylum Eurhodophytina
Class Florideophyceae
Subclass Corallinophycidae
Order Hapalidiales
Family Hapalidiaceae
Subfamily Austrolithoideae

Holotype species: Boreolithon vanheurckii (Heydrich) A.S.Harvey & Woelkerling

Original publication and holotype designation: Harvey, A.S. & Woelkerling, W.J. (1995). An account of Austrolithon intumescens gen. et. sp. nov. and Boreolithon van-heurckii (Heydrich) gen. et. comb. nov. (Austrolithoideae subfam. nov., Corallinaceae, Rhodophyta). Phycologia 34: 362-382.

Precise date of publication25 September 1995

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
The ICBN rules cited below are those adopted by the Seventeenth International Botanical Congress, Vienna, Austria, July 2005 (McNeill et al. 2006).

In accordance with ICBN Art 13.3, the name Boreolithon is treated as pertaining to a non-fossil taxon because its type is based on a non-fossil specimen. No species based on fossil types have been assigned to the genus to date.

The generic name Boreolithon is typified (ICBN Art 10.1) by the type of B. vanheurckii, the only species originally included in the genus. - (17 Jul 2009) - M.D. Guiry

Description: Plants calcified, lacking genicula, entirely pseudoparenchymatous; encrusting in growth-form and epigenous, growing attached to hydroids (the only known substrate); haustoria unknown.

Thallus organization wholly dorsiventral; thallus construction dimerous throughout, composed of two groups of filaments: a ventral-most unistratose layer of filaments (primigenous filaments) from which marginal growth occurs; and epithallial cells (see comments) that arise vertically from cells of ventral filaments; outermost walls of epithallial cells apparently rounded or flattened but not flared at the corners; cell-elongation characteristics uncertain; cells of adjacent filaments apparently not linked by cell fusions or by secondary pit-connections.

Gametangia and carposporangia unknown.

Tetrasporangia unknown. Bisporangia formed in conceptacles. Roofs of bisporangial conceptacles multiporate and composed of cells. Bisporangia each containing two zonately arranged spores and producing an apical plug that blocks a roof pore before spore release.

Information contributed by: Wm. J. Woelkerling. The most recent alteration to this page was made on 20 Jan 2017 by M.D. Guiry.

Characters considered diagnostic of Boreolithon: Characters collectively considered diagnostic of the genus: Boreolithon is the only known genus of Hapalidiaceae, Subfamily Austrolithoideae with: 1) a pseudoparenchymatous thallus growing upon, not within, a substrate; and 2) dimerous thallus construction.

Characters considered diagnostic of higher taxonomic ranks known/presumed to occur in all species of Boreolithon: Characters considered diagnostic of higher taxonomic ranks and known/presumed to occur in Boreolithon: 1) calcification in the form of calcite; 2) pit plugs with two cap layers at cytoplasmic faces, the outer cap dome shaped; membrane absent; 3) cell walls impregnated with calcite; 4) gametangia and carposporangia produced within uniporate conceptacles; 5) tetrasporangia/bisporangia possessing zonately arranged spores and produced within conceptacles; 6) tetrasporangial/bisporangial conceptacles possessing multiporate plates or roofs; 7) tetrasporangia/bisporangia producing apical plugs; 8) tetrasporangial/bisporangial conceptacles with multiporate roofs composed of cells; lacking an acellular multiporate plate recessed below a single outer opening; and 9) cells of contiguous vegetative filaments not linked by cell fusions or by secondary pit-connections. Characters 1-2 are considered diagnostic of the Corallinophycidae, 3-5 of the Corallinales, 6-7 of the Hapalidiaceae, and 8-9 of the Austrolithoideae.

Generic synonyms: No synonyms of Boreolithon are known.

Comments: Knowledge of Boreolithon is based on the original account of Harvey & Woelkerling (1995), but because the type and only known species, B. vanheurckii, is based solely on bisporangial plants, the status of Boreolithon as a distinct genus of Austrolithoideae may require further evaluation. B. vanheurckii, was originally described as a species of Lithothamnion; the rather contorted taxonomic history of the species is summarized by Harvey & Woelkerling (1995: 374). Growth-form terminology follows (Woelkerling et al. 1993).

The lectotype of B. vanheurckii has been studied and illustrated most recently by Chamberlain & Irvine (1994: 199-201, figs 95-96, as Melobesia) and by Harvey & Woelkerling (1995: 374-377, figs 42, 46-50), who listed earlier references to the species. Epithallial cells were recorded in the lectotype by Chamberlain & Irvine (1994) and also were reported by Chalon (1905) and Cabioch (1972: 179), but Harvey & Woelkerling (1995) were unable to detect epithallial cells in the lectotype. In addition, Chalon (1905: 208), Heydrich (1905: [2]), Cabioch (1972: 179) and Chamberlain & Irvine (1994: 199, 200) all suggested that the species was not calcified, whereas Harvey & Woelkerling (1995: 376) determined from scanning electron microscopy and x-ray microanalysis that lectotype plants were calcified. Neither cell fusions nor secondary pit-connections have been reported.

Biogeographically, Boreolithon presently is known only from Jersey (Channel Islands, United Kingdom) and northern France (Golfe de St. Malo, Bay of Biscay).

The lists below of diagnostic characters of Boreolithon, and of the higher taxa to which it belongs, are derived from data in Harvey & Woelkerling (1995), Harvey, Broadwater, Woelkerling & Mitrovski (2003), Harvey, Woelkerling & Millar (2003), Le Gall & Saunders (2007), Woelkerling et al. (2008: 282) and/or Le Gall et al. (2009). Diagnostic characters are those that taken together distinguish a taxon from others of the same taxonomic rank (e.g. characters distinguishing Boreolithon from other genera of the Hapalidiaceae, subfamily Austrolithoideae.

Numbers of names and species: There is only one species or infraspecific name in the database at present, which 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.

References
Cabioch, J. (1972). Étude sur les Corallinacées. II - La morphogenèse : conséquences systématiques et phylogénétiques. Cahiers de Biologie Marine 13: 137-288.

Chalon, J. (1905). Liste des algues marines observées jusqu'à ce jour entre l'Embouchure de l'Escaut et la Corogne (incl. Iles Anglo-Normandes). pp. [1]-259. Anvers: Imprimerie J.-E. Buschmann, rempart de la Porte du Rhin.

Chamberlain, Y.M. & Irvine, L.M. (1994). Melobesioideae Bizzozero. In: Seaweeds of the British Isles. Volume 1. Rhodophyta Part 2B Corallinales, Hildenbrandiales. (Irvine, L.M. & Chamberlain, Y.M. Eds), pp. 159-234. London: HMSO.

Harvey, A.S., Broadwater, S.T., Woelkerling, W.J. & Mitrovski, P.J. (2003). Choreonema (Corallinales, Rhodophyta): 18S rDNA phylogeny and resurrection of the Hapalidiaceae for the subfamilies Choreonematoideae, Austrolithoideae and Melobesioideae. Journal of Phycology 39: 988-998.

Harvey, A.S. & Woelkerling, W.J. (1995). An account of Austrolithon intumescens gen. et. sp. nov. and Boreolithon van-heurckii (Heydrich) gen. et. comb. nov. (Austrolithoideae subfam. nov., Corallinaceae, Rhodophyta). Phycologia 34: 362-382.

Harvey, A.S., Woelkerling, W.J. & Millar, A.J.K. (2009). The genus Amphiroa (Lithophylloideae, Corallinaceae, Rhodophyta) from the temperate coasts of the Australian continent, including the newly described A. klochkovana. Phycologia 48: 258-290.

Heydrich, F. (1905). Note sur l'Épilithon van heurckii Heyd. pp. [2]. City of publication not indicated: Publisher not indicated.

Le Gall, L., Payri, C.E., Bittner, C.E., & Saunders, G.W. (2010). Multigene polygenetic analyses support recognition of the Sporolithales, ord. nov. Molecular Phylogenetics and Evolution 54(1): 302-305.

Le Gall, L. & Saunders, G.W. (2007). A nuclear phylogeny of the Florideophyceae (Rhodophyta) inferred from combined EF2, small subunit and large subunit ribosomal DNA: establishing the new red algal subclass Corallinophycidae. Molecular Phylogenetics and Evolution 43: 1118-1130.

McNeill, J., Barrie, F.R., Burdet, H.M., Demouline, V., Hawksworth, D.L., Marhold, K., Nicolson, D.H., Prado, J., Silva, P.C., Skog, J.E., Wiersema, J.H. & Turland, N.J. (2006). International Code of Botanical Nomenclature (Vienna Code) adopted by the Seventeenth International Botancial Congress Vienna, Austria, July 2005. pp. [i-iv], v-xviii + 1-568. Liechtenstein: A.R.G. Gantner Verlag.

Woelkerling, W.J. & Harvey, A.S. (1996). Subfamily Austrolithoideae. In: The marine benthic flora of Southern Australia – Part IIIB. Gracilariales, Rhodymeniales, Corallinales and Bonnemaisoniales . (Womersley, H.B.S. Eds), pp. 160-163. Canberra: Australian Biological Resources Study.

Woelkerling, W.J., Irvine, L.M. & Harvey, A.S. (1993). Growth-forms in non-geniculate coralline red algae (Corallinales, Rhodophyta). Australian Systematic Botany 6: 277-293.

Woelkerling, W.J., Millar, A.J.K., Harvey, A. & Baba, M. (2008). Recognition of Pachyarthron and Bossiella as distinct genera in the Corallinaceae, subfamily Corallinoideae (Coarllinales, Rhodophyta). Phycologia 47: 265-293.

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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.

Created: 28 December 2000 by M.D. Guiry

Verified by: 20 January 2017 by M.D. Guiry

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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 25 September 2018.

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