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Phymatolithon Foslie, 1898, nom. cons.

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

Holotype species: Phymatolithon polymorphum Foslie

Currently accepted name for the type species: Phymatolithon calcareum (Pallas) W.H.Adey & D.L.McKibbin ex Woelkering & L.M.Irvine

Original publication and holotype designation: Foslie, M. (1898). Systematical survey of the Lithothamnia. Det Kongelige Norske Videnskabers Selskabs Skrifter 1898(2): 1-7.
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Precise date of publication14 October 1898 (see Woelkerling 1993: 278 for details).

Taxonomic status: currently recognized as a distinct genus.

Gender: This genus name is currently treated as neuter.

Most recent taxonomic treatment adopted: Irvine, L.M. & Woelkerling, W.J. (1986). Proposal to conserve Phymatolithon against Apora (Rhodophyta: Corallinaceae). Taxon 35: 731-733.

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

The generic name Phymatolithon is typified (ICBN Art. 10.1) by the type of P. polymorphum Foslie, nom. illeg. the only species originally included in the genus. Although Foslie based his species name on Millepora polymorpha Linnaeus (1767: 1285), Foslie's binomial is correctly cited as Phymatolithon polymorphum Fosile and not P. polymorphum (Linnaeus) Foslie because Millepora polymorpha Linnaeusis illegitimate (see below) and thus cannot serve as a basionym (ICBN Art. 45.3). Phymatolithon polymorphum Foslie is considered to be a new name (ICBN Art. 58) but is also illegitimate because Foslie did not explicitly exclude the type of Millepora calcarea Pallas (see ICBN Art. 58, Note 1) from his species.

Millepora polymorpha Linnaeus and Phymatolithon polymorphum Foslie are illegitimate (ICBN Art. 52) because they are superfluous substitute names for Millepora calcarea Pallas (1766: 265). In accordance with ICBN Art. 7.5, Millepora polymorpha and Phymatolithon polymorphum are automatically typified by the type of M. calcarea, the name that ought to have been adopted under the rules. Because the type of Millepora calcarea Pallas typifies the name Phymatolithon polymorphum Foslie, it also typifies the generic name Phymatolithon (ICBN Art. 10.1).

The current correct name for M. calcarea is Phymatolithon calcareum (Pallas) Adey & McKibbin (1970: 100). Details are provided in Woelkerling & Irvine 1986.

Phymatolithon Foslie (1898) is formally conserved against Apora Gunnerus (1768) under ICBN Art 14 and is listed in the Nomina Generica Conservanda (ICBN, Appendix III, A9). In accordance with ICBN Art. 14.4, Phymatolithon is also automatically conserved against all other homotypic synonyms (generic names based on the same type); these are listed under Synonyms below.

Further data relating to the conservation of Phymatolithon Foslie are provided in Woelkerling & Irvine (1986), Irvine & Woelkerling (1986) Woelkerling (1988: 199). Apora Gunnerus (1768) is listed opposite Phymatolithon Foslie in Appendix III, A9 as the earliest homotypic (nomenclatural) synonym.

Woelkerling & Irvine (1986: 58) designated a specimen in the Natural History Museum, London (BM, Algal Box Collection 1626) as neotype of Millepora calcarea Pallas. Spencer et al. (2009: 253) noted, however, that subsequent changes in the International Code of Botanical Nomenclature meant that this neotypification had to be superseded. Consequently L.M. Irvine (in Spencer et al. 2009: 253) lectotypified the species with one of the illustrations cited in the protologue by Pallas (1766), namely Tab. 27, fig. C in Ellis (1755), and Woelkerling & Irvine (in Spencer et al. 2009: 253) then designated the specimen in BM Algal Box Collection 1626 (BM 000562555, depicted in Woelkerling & Irvine 1986: figs 1A, 2-15) as epitype.

The application of ICBN Art 45.3 & Art. 58 in determining authorship and illegitimacy was ascertained in email correspondence in May 2009 with Paul Silva (Chairman, Permanent Nomenclature Committee for Algae) and John McNeill (Chairman, Editorial Committee for the International Code of Botanical Nomenclature adopted by the Seventeenth International Botanical Congress, Vienna, Austria, July 2005) - (20 Jul 2009) - M.D. Guiry

Description: Plants calcified, lacking genicula, entirely pseudoparenchymatous; encrusting to warty, lumpy, fruticose, discoid, layered or foliose; epigenous and growing partially to completely attached to the surface of various substrates (e.g. 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. Most filaments usually terminating at the thallus surface in epithallial cells (generally one per filament); outermost walls of epithallial cells rounded or flattened but not flared at the corners; cell elongation occurring mainly behind actively dividing subepithallial initials that are usually as short as or shorter 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) produced in separate conceptacles; 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 2-3 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 10 Aug 2021 by E.A. Molinari Novoa.

Characters considered diagnostic of Phymatolithon: Characters collectively considered diagnostic of Phymatolithon: Phymatolithon is the only known genus of Hapalidiaceae, Subfamily Melobesioideae with: 1) a thallus that is not arborescent [i.e. composed of a basal holdfast and erect stipes bearing flexible ribbon-like branches]; 2) subepithallial initials usually as short as or shorter than their immediate inward derivatives; and 3) haustoria absent.

The occurrence of pigmentation, especially in living specimens provides a good indication that haustoria do not occur. Kvaleya, which shares the first two diagnostic characters, possesses haustoria, lacks pigmentation and forms small pustule-like thallus several mm across on Phymatolithon tenue.

Characters considered diagnostic of higher taxonomic ranks known/presumed to occur in all species of Phymatolithon: Characters considered diagnostic of higher taxonomic ranks and known/presumed to occur in all species of Phymatolithon: 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: Because Phymatolithon is a conserved name, it is automatically conserved against all other generic names based on the same type (i.e. homotypic synonyms). Chronologically these are Apora Gunnerus (1768), Nullipora Lamarck (1801), Agardhina Nardo (1834), Agardhia Meneghini (1838), Juergensia Reichenbach (1841), and Eleutherospora Heydrich (1900). See AlgaeBase entries for these names for further information.
Leptophytum Adey (1966) and Squamolithon Heydrich (1911) are regarded as heterotypic synonyms of Phymatolithon. See AlgaeBase entries for these names for further information.
Although nomenclaturally incorrect, the name Leptophytum has continuedto be used by some authors; for further information see AlgaeBase entry for this genus.

Comments: Comments: Information on the taxonomic history, nomenclature, and other matters associated with the name Phymatolithon is contained in Woelkerling (1988: 197-203). Growth form terminology (encrusting, lumpy, fruticose, etc.) follows Woelkerling et al. (1993).

An account of the epitype specimen of Phymatolithon calcareum, the type species of Phymatolithon, is presented in Woelkerling & Irvine (1986). Cabioch (1970) provides information on gametangial plants, and additional data on the species, including references is summarized in Chamberlain & Irvine (1994: 212-215).

The types and other specimens of a number of species and infraspecific taxa currently referred to Phymatolithon need to be re-examined in detail to verify whether generic placement is correct, to re-assess whether recognition as a distinct species or infraspecific taxon 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 and each infraspecific taxon from others assigned to the same species. At present, a number species and infraspecific taxa assigned to Phymatolithon are poorly or incompletely known.

Biogeographically, Phymatolithon is recorded fromtemperate and colder water environments in both the northern and southern hemispheres, but a number of published records require confirmation.

The lists below of diagnostic characters of Phymatolithon, and of the higher taxa to which it belongs, are derived from data in Harvey, Broadwater, Woelkerling & Mitrovski (2003), Harvey, Woelkerling & Millar (2003), Le Gall & Saunders (2007), Woelkerling et al. (2008: 282) and/or Lre 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 Phymatolithon from other genera of the Hapalidiaceae, subfamily Melobesioideae). Harvey, Woelkerling & Millar (2003: 653) also provide a diagnostic comparison of Mesophyllum with other currently recognized non-fossil genera of Melobesioideae.

Numbers of names and species: There are 37 species names in the database at present, as well as 20 infraspecific names. Of the species names, 22 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.

Adey, W.H. (1966). The genera Lithothamnium, Leptophytum (nov. gen.) and Phymatolithon in the Gulf of Maine. Hydrobiologia 28: 321-370, 112 figs, tables I-VI.

Adey, W.H. & McKibbin, D.L. (1970). Studies on the maerl species Phymatolithon calcareum (Pallas) nov. comb. and Lithothamnium corallioides Crouan in the Ria de Vigo. Botanica Marina 13: 100-106, 16 figs.

Cabioch, J. (1970). Le maërl des côtes de Bretagne et le problème de la survie. Penn ar Bed 7: 421-429.

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.

Ellis, J. (1755). An essay towards a natural history of the corallines, and other marine productions of the like kind, commonly found on the coasts of Great Britain and Ireland. To which is added the description of a large marine polype taken near the North Pole, by the whale-fishers, in the summer 1753. pp. [i]-xvii, [10 p. cont., err.], [i]-i03, frontispiece, pl. 1-37 [+2 unnumbered], copperplate. London: Printed for the Authors;. and Sold by A. Millar, in the Strand; J. and J. Rivington, in St. Paul's Church-Yard; and R. and J. Dodsley, in Pall-Mall.

Foslie, M. (1898). Systematical survey of the Lithothamnia. Det Kongelige Norske Videnskabers Selskabs Skrifter 1898(2): 1-7.

Gunnerus, J.E. (1768). Om nogle norske Coraller [On some Norwegian corals]. Det Kongelige Norske Videnskabers Selskabs Skrifter 4: 38-73, pls 1-4, 8, 10, 11, 15.

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. (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. (1900). Die Lithothamnien von Helgoland. Wissenschaftliche Meeresuntersuchungen, N.F. 4 (Abt. Helgoland): 63-82, pl. 2.

Heydrich, F. (1911). Die Lithothamnien von Roscoff. Berichte der deutsche botanischen Gesellschaft 29: 26-32, 1 plate.

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.

Irvine, L.M. & Woelkerling, W.J. (1986). Proposal to conserve Phymatolithon against Apora (Rhodophyta: Corallinaceae). Taxon 35: 731-733.

Lamarck, J.B. de (1801). Systeme des Animaux sans vertebres, ou tableau général des classes, des ordres et des genres de ces animaux; Présentant leurs caractères essentiels et leur distribution, d'après la considération de leurs rapports naturels et de leur organisation, et suivant l'arrangement établi dans les galeries du Muséum d'Hist. Naturelle, parmi leurs dépouilles conservées. Précédé du discours d'ouverture du Cours de Zoologie, donné dans le Muséum National d'Histoire Naturelle l'an 8 de la République.. pp. i-viii, 1-432. Paris: Chez l'Auteur, au Muséum d'Hist[oire] Naturelle; Chez Derteville, Libraire, rue du Battoir n° 16, quartier de l'Odéon..

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.

Linnaeus, C. (1767). Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus & differentiis. Tomus II. Editio duodecima, reformata. pp. 533-1327 [1328] [+ 1-36]. Homiae [Stockholm]: impensis direct. Laurentii Salvii.

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.

Meneghini, G. (1838). Cenni sulla organographia e fisiologia delle alghe. Nuovi Saggi della [Cesarea] Regia Accademia di Scienze, Lettere ed Arti di Padova 4: 325-388.

Nardo, G.D. (1834). De corallinis ac nulliporis auct. Isis von Oken 1834(1): 673-675.

Pallas, P.S. (1766). Elenchus zoophytorum sistens generum adurnbrationes generaliores et specierum cognitarum succinctas descriptiones cum selectis auctorum synonymis. pp. [i]-xvi + [17]-451. Hagae-Comitum ['s Gravenhage; The Hague]: apud Petrum van Cleef.

Reichenbach, H.G.L. (1841). Repertorium herbarii, sive, Nomenclator generum plantarum systematicus synonymicus et alphabeticus ad usum practicum accommodatus... pp. i-xxv, 1-214, 1-240. Dresden: Arnold.

Spencer, M.A., Irvine, L.M. & Jarvis, C.E. (2009). Typification of Linnaean names relevant to algal nomenclature. Taxon 58: 237-260.

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. (1986). The typification and status of Phymatolithon (Corallinaceae, Rhodophyta). British Phycological Journal 21: 55-80, 18 figs.

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., 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.

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: 01 January 2001 by M.D. Guiry

Verified by: 07 April 2018 by M.D. Guiry

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M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2021. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 23 October 2021.

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