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Lithothamnion Heydrich, 1897, nom. et typ. cons.

Classification:
Empire Eukaryota
Kingdom Plantae
Subkingdom Biliphyta
Phylum Rhodophyta
Subphylum Eurhodophytina
Class Florideophyceae
Subclass Corallinophycidae
Order Corallinales
Family Lithothamniaceae
Tribe Lithothamnieae

Holotype species: Lithothamnion muelleri Lenormand ex Rosanoff

Original publication:Heydrich, F. (1897). Melobesiae. Berichte der deutsche botanischen Gesellschaft 15: 403-420, pl. XVIII [18].
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Type designated in Woelkerling, W.J. (1983). A taxonomic reassessment of Lithothamnium (Corallinaceae, Rhodophyta) based on studies of R. A. Philippi's original collections. British Phycological Journal 18(2): 165-197, 33 figs, IV tables.

Precise date of publication7 September 1897 (see Woelkerling & Lamy 1998: 680 for details). The requirements for valid publication are specified in the ICBN(International Code of Botanical Nomenclature).

Taxonomic status: currently recognized as a distinct genus.

Gender: This genus name is currently treated as neuter.

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 Lithothamnion Heydrich is treated as pertaining to a non-fossil taxon because its type is based on a non-fossil specimen. Both non-fossil and fossil species have been assigned to the genus.

The generic name Lithothamnion Heydrich is typified (ICBN Art 10.1) by the type of L. muelleri, the designated lectotype species of Lithothamnion and one of 71 names (Heydrich 1897) originally included in the genus.

Lithothamnion Heydrich (1897) is nomenclaturally conserved against Lithothamnium Philippi (1837) and is listed in the Nomina Generica Conservanda (ICBN Appendix III, A9). Further data relating to the conservation of Lithothamnion Heydrich are provided in Woelkerling 1983: 193-194, Woelkerling 1985, and Woelkerling 1988: 173. Lithothamnium Philippi (1837) is listed opposite Lithothamnion Heydrich in ICBN Appendix III, A9 as an earlier homonym. The spelling Lithothamnium should not be used for species belonging to Lithothamnion Heydrich but rather should be changed without alteration to authorship or date in accordance with ICBN Art. 55.3. - (27 Aug 2009) -

Description:

Plants calcified, lacking genicula, entirely pseudoparenchymatous; encrusting to warty, lumpy or fruticose; epigenous and growing partially to completely attached to the surface of various substrates (e.g. algae, molluscs, rock), or growing unattached and free-living as rhodoliths; haustoria unknown.

Thallus organization generally dorsiventral in crustose portions but more or less radial in branches; thallus construction monomerous throughout, consisting of a single system of branched laterally coherent filaments that contribute to a ventral or central core and a peripheral region where portions of core filaments or their derivatives curve outwards towards the thallus surface; coaxial growth (in which cells of adjacent filaments in core region are aligned in arching tiers) apparently not recorded. Most filaments usually terminating at the thallus surface in epithallial cells (generally one per filament); outermost walls of epithallial cells flattened with flared corners; cell elongation occurring mainly within actively dividing subepithallial initials that are usually as long as or longer than their immediate inward derivatives. Cells of adjacent filaments linked by fusions; secondary pit-connections unknown.

Gametangia (where known) and carposporangia (where known) developing in uniporate conceptacles. Spermatangia (male gametangia) and carpogonia (female gametangia) almost always produced in separate conceptacles (very rarely in the same conceptacle); male and female conceptacles occasionally formed on the same plant but much more commonly formed on different plants. Spermatangia (where known) formed on branched and unbranched filaments that arise from the conceptacle chamber floor and roof; spermatangial initials (where known) apparently not overlain with protective cells during early stages of development; spermatangial conceptacle roof formation (where known) occurring centripetally from groups of vegetative filaments peripheral to developing spermatangial filaments on the conceptacle chamber floor. Carpogoina (where known) terminating 2-4 celled unbranched filaments that arise from the conceptacle chamber floor. Carposporophytes (where known) developing in carpogonial conceptacles after presumed fertilization; mature carposporophytes apparently lacking a conspicuous central fusion cell but possessing several-celled filaments bearing terminal carposporangia.

Tetrasporangia/bisporangia formed in conceptacles on separate plants from gametangia and carposporangia. Roofs of tetrasporangial/bisporangial conceptacles multiporate and composed of cells. Tetrasporangia each containing four zonately arranged spores and producing an apical plug that blocks a roof pore before spore release. Bisporangia each containing two spores but otherwise similar to tetrasporangia.

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 Lithothamnion: Lithothamnion is the only known genus of Hapalidiaceae, Subfamily Melobesioideae with: 1) monomerous thallus construction throughout; and 2) epithallial cells with outermost walls flattened and possessing flared corners.

Characters considered diagnostic of higher taxonomic ranks known/presumed to occur in all species of Lithothamnion: 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 produced within conceptacles and possessing zonately arranged spores; 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 linked exclusively by cell fusions. Characters 1-2 are considered diagnostic of the Corallinophycidae, 3-5 of the Corallinales, 6-7 of the Hapalidiaceae, and 8-9 of the Melobesioideae.

Generic synonyms: No synonyms of Lithothamnion Heydrich (1897) are currently included in AlgaeBase. Lithothamnion Heydrich (1897), however, is conserved against Lithothamnium Philippi (1837) (see Nomenclatural notes above).

Comments: Information on the taxonomic history, nomenclature, and other matters associated with the name Lithothamnion Heydrich is contained in Woelkerling (1988: 171-175). Growth form terminology (encrusting, lumpy, fruticose, etc.) follows Woelkerling et al. (1993).

An account of the lectotype specimen of Lithothamnion muelleri, the lectotype species of Lithothamnion, is presented in Woelkerling (1983: 190-192, figs 29-33); additional figures of the lectotype are included in Wilks & Woelkerling (1995: 572-573, figs 1A, 2A), who also provide a detailed account of the species.

The types and other specimens of most species currently referred to Lithothamnion need to be re-examined in detail to verify whether generic placement is correct, to re-assess whether recognition as a distinct species is justified, to understand more fully the extent of infraspecific morphological and anatomical variation, and to determine the diagnostic characters that separate each species from others within the genus. At present, most species assigned to Lithothamnion are poorly or incompletely known.

Biogeographically, Lithothamnion appears to be widespread, but many records require confirmation.

The lists below of diagnostic characters of Lithothamnion, and of the higher taxa to which it belongs, are derived from data in Woelkerling (1988), 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 Lithothamnion from other genera of the Hapalidiaceae, subfamily Melobesioideae). Harvey, Woelkerling & Millar (2003: 653) also provide a diagnostic comparison of Lithothamnion with other currently recognized non-fossil genera of Melobesioideae.
Lithothamnion (Hughey et al. 2008).

Common names

(as Lithothamnion)
Finnish: Punalevä-suku (European Communities 1998).

French: Maërl (European Communities 1998).

Numbers of names and species: There are 284 species names in the database at present, as well as 240 infraspecific names. Of the species names, 83 have 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
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. & Millar, A.J.K. (2003). An account of the Hapalidiaceae (Corallinales, Rhodophyta) in south-eastern Australia. Australian Systematic Botany 16: 647-698.

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. (1897). Melobesiae. Berichte der deutsche botanischen Gesellschaft 15: 403-420, pl. XVIII [18].

Hughey, J.R., Braga, J.C., Aguirre, J., Woelkerling, W.J. & Webster, J.M. (2008). Analysis of ancient DNA from fossil corallines (Corallinales, Rhodophyta). Journal of Phycology 44: 374-383.

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.

Philippi, R.A. (1837). Beweis, dass die Nulliporen Pflanzen sind. Archiv für Naturgeschichte 3: 387-393, figs 2-6, pl. IX.

Rosanoff, S. (1866). Recherches anatomiques sur les Mélobésiées (Hapalidium, Melobesia, Lithophyllum et Lithothamnion). Mémoires de la Société Impériale des Sciences Naturelles de Cherbourg 12: 5-112, pls I-VII.

Wilks, K.M. & Woelkerling, W.J. (1995). An account of southern Australian species of Lithothamnion (Corallinaceae, Rhodophyta). Australian Systematic Botany 8: 549-583, 12 figs, 2 tables.

Woelkerling, W.J. (1983). A taxonomic reassessment of Lithophyllum (Corallinaceae, Rhodophyta) based on studies of R.A. Philippi's original collections. British Phycological Journal 18(3): 299-328.

Woelkerling, W. J. (1985). Proposal to conserve Lithothamnion against Lithothamnium (Rhodophyta: Corallinaceae). Taxon 34: 302-303.

Woelkerling, W.J. (1988). The Coralline Red Algae: an analysis of the genera and subfamilies of nongeniculate Corallinaceae. pp. i-xi, 1-268, 259 figs, tables numbered by chapter. London & Oxford: British Museum (Natural History) & Oxford University Press.

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. & Lamy, D. (1998). Appendix 3. Effective Publication Dates. In: Non-geniculate Coralline Red Algae and the Paris Muséum: Systematics and Scientific History . (Woelkerling, W.J. & Lamy, D. Eds), pp. 671-682. Paris: Publications Scientifique du Muséum/ADAC.

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 (Corallinales, Rhodophyta). Phycologia 47: 265-293.

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: 29 December 2000 by M.D. Guiry

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

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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 17 October 2018.

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