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Melobesia J.V.Lamouroux, 1812

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

Holotype species: Melobesia membranacea (Esper) J.V.Lamouroux

Original publication and holotype designation: 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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Precise date of publication1812 (more precise date not determined). The requirements for valid publication are specified in the ICBN (International Code of Botanical Nomenclature).

Taxonomic status: currently recognized as a distinct genus.

Most recent taxonomic treatment adopted: Athanasiadis, A. (2016). Phycologia Europaea Rhodophyta Vol. I. pp. [i]-xxxxviii, 1-762. Thessaloniki: Published and distributed by the author.

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 Melobesia J.V. Lamouroux 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 Melobesia J.V. Lamourouxis typified (ICBN Art 10.1) by the type of M. membranacea, the only validly published species included in the original publication (see Mason 1953: 319; Chamberlain 1983: 297, 298; Woelkerling 1988: 189).

Chamberlain (1985: 675, fig. 2) designated an unnumbered specimen in the Lamouroux herbarium (CN) as neotype of M. membranacea. Woelkerling & Chamberlain (2007) noted, however, that subsequent changes in the ICBN meant that this neotypification had to be superseded, and they lectotypified the species with original protologue illustrations (Esper 1796, Corallina Tab XII, figs 2, 3 & 4) and then designated the unnumbered specimen in the Lamouroux herbarium as epitype.

Melobesia J.V. Lamouroux (1812) is not to be confused with the later illegitimate homonyms Melobesia Heydrich (1897) and Melobesia Foslie (1898). - (16 Jan 2009) -

Description: Plants calcified, lacking genicula, largely or entirely pseudoparenchymatous; encrusting; and epigenous and normally growing completely attached to the surface of various substrates (most commonly other algae); 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 upright filaments (postigenous filaments) one or more cells long that arise perpendicularly from cells of ventral filaments and lead to increased thallus thickness. Upright filaments each normally terminating at the thallus surface in an epithallial cell; outermost epithallial cell walls rounded or flattened but not flared at the corners; subepithallial cell elongation characteristics uncertain. 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 different conceptacles; male and female conceptacles occasionally formed on the same plant but much more commonly formed on different plants. Spermatangia (where known) formed on unbranched filaments arising from the conceptacle chamber floor and roof; layer of degenerative ‘protective cells’ overlying spermatangial initials not recorded; mode of spermatangial roof formation uncertain. Carpogonia (where known) terminating 2-3 celled unbranched filaments arising from the conceptacle chamber floor. Carposporophytes (where known) developing in carpogonial conceptacles after presumed fertilization, apparently composed either of one (or possibly several) inconspicuous fusion cells or lacking an evident fusion cell, but always 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 Melobesia: Characters collectively considered diagnostic of Melobesia: Melobesia Lamouroux is the only known genus of Hapalidiaceae, Subfamily Melobesioideae with: 1) dimerous thallus construction throughout; and 2) epithallial cells that are rounded or flattened but not flared.

Characters considered diagnostic of higher taxonomic ranks known/presumed to occur in all species of Melobesia: 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: Epilithon Heydrich (1897: 408) is a homotypic synonym of Melobesia Lamouroux; Hapalidium Kützing (1843: 385) is regarded as a heterotypic synonym. See AlgaeBase entries for these names for further information. The later illegitimate homonyms Melobesia Heydrich (1897) and Melobesia Foslie (1898) also are dealt with in separate AlgaeBase entries.

Comments: Information on the taxonomic history, nomenclature, and other matters associated with the name Melobesia Lamourouxis contained in Woelkerling (1988: 189-190), and additional data are provided in Wilks & Woelkerling (1991). Growth form terminology follows Woelkerling et al. (1993).

Accounts of the epitype specimen of Melobesia membranacea, the type species of Melobesia Lamouroux, are presented in Chamberlain (1985) and Wilks & Woelkerling (1991)..

Uncertainty attends the mode of spermatangial conceptacle roof formation in Melobesia. Based on drawings and comments in Kylin (1928:39-40, Fig 20, as Epilithon), repeated by Suneson (1937: 60-61, as Epilithon), Lebednik (1978:392) and Chamberlain et al.(1995: 450-451) suggested that roof formation in Melobesia was similar to that in Clathromorphum (in which the roof forms vertically from filaments that also produce vertical pairs of spermatangial initials that at first are linked by primary pit-connections (Lebednik 1978: 394, fig. 12); the conceptacle chamber forms vertically when the pairs of spermatangial initials split apart). Kylin’s (1928) observations have yet to be confirmed, and apparently there are no published photographic figures showing early developmental stages for any species currently placed in Melobesia.

The types and other specimens of most species currently referred to Melobesia Lamouroux 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 Melobesia are poorly or incompletely known

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

The lists below of diagnostic characters of Melobesia, 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 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 Melobesia from other genera of the Hapalidiaceae, subfamily Melobesioideae). Harvey, Woelkerling & Millar (2003: 653) also provide a diagnostic comparison of Melobesia with other currently recognized non-fossil genera of Melobesioideae.

Numbers of names and species: There are 113 species names in the database at present, as well as 12 infraspecific names. Of the species names, 18 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
Chamberlain, Y.M. (1983). Studies in the Corallinaceae with special reference to Fosliella and Pneophyllum in the British Isles. Bulletin of the British Museum (Natural History) Botany 11: 291-463, 89 figs.

Chamberlain, Y.M. (1985). The typification of Melobesia membranacea (Esper) Lamouroux (Rhodophyta, Corallinaceae). Taxon 34: 673-677, 4 figs, 1 table.

Chamberlain, Y.M., Norris, R.E., Keats, D.W. & Maneveldt, G. (1995). Clathromorphum tubiforme sp. nov. (Rhodophyta, Corallinaceae) in South Africa with comments on generic characters. Botanica Marina 38: 443-453, 29 figs, 1 table.

Esper, E.J.C. (1796). Fortsetzungen der Pflanzenthiere in Abbildungen nach der Natur mit Farben erleuchtet nebst Beschreibungen. Lieferung 6. pp. 149-168, 11 plates [numbered by genus]. Nürnberg.

Foslie, M. (1898). List of species of the Lithothamnia. Kongelige Norske Videnskabers Selskabs Skrifter 1898(3): 1-11.

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].

Kützing, F.T. (1843). Phycologia generalis oder Anatomie, Physiologie und Systemkunde der Tange. Mit 80 farbig gedruckten Tafeln, gezeichnet und gravirt vom Verfasser. pp. [part 1]: [i]-xxxii, [1]-142, [part 2:] 143-458, 1, err.], pls 1-80. Leipzig: F.A. Brockhaus.

Kylin, H. (1928). Entwicklungsgeschichtliche Florideenstudien. Lunds Univ. Arsskr. N.F. Avd. 2 84(4): 1-127.

Lebednik, P.A. (1978). Development of male conceptacles in Mesophyllum Lemoine and other genera of the Corallinaceae (Rhodophyta). Phycologia 17: 388-395.

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.

Suneson, S. (1937). Studien über die entwicklungsgeschichte der Corallinaceen. Lunds Univ. Arsskr. N.F. Avd. 2 33(2): 1-102, 4 plates.

Wilks, K.M. & Woelkerling, W.J. (1991). Southern Australian species of Melobesia (Corallinaceae, Rhodophyta). Phycologia 30: 507-533, 37 figs, 2 tables.

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. & Chamberlain, Y.M. (2007). The genus Melobesia (Hapalidiceae, Corallinales, Rhodophyta): typification update. Phycologia 46: 232-234.

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: 29 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 19 November 2018.

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