Clathromorphum Foslie, 1898

Lectotype species: Clathromorphum compactum (Kjellman) Foslie

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

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Type designated in: Lemoine, Mme P. [=M.] (1911). Structure anatomique des Mélobésiées. Application à la classification. Annales de l'Institut Océanographique, Monaco 2(2): 1-213, 14 figs, 3 folded tables, pls I-V.

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Description: Nongeniculate, encrusting, epilithic, coralline; multifilament hypothallium sub-parallel to substratum, mostly arching upward to form perithallium, some filaments arching downward, dead-ending on substratum; cells of adjacent filaments linked by fusions, secondary pit-connections unknown; epithallium thick, 3-14 cell layers (largely dependent on level of invertebrate grazing), epithallial cells with abundant plastids and outermost walls of terminal epithallial cells rounded or flattened but not flared at the corners; meristem intercalary and below epithallium; meristematic cells usually as long as or longer than their immediate inward derivatives; growth (cell division and elongation) and cell wall calcification occurring only in meristematic cells in a narrow (1-2 um wide), often un- or weakly calcified horizontal plane (meristem split) before formation of transverse cell walls; double mode of calcification with primary, small, prismatic, radial calcite crystals within cell walls with secondary, large, diagonal, deltoid inter filament crystals between cell filaments in perithallium; in epithallium interfilament crystals few, vertical and plate-like; all conceptacle fertile discs developed directly from the meristem, sunken at maturity; intersporangial filaments initially calcified, dissolved when sporangia mature; bi/tetrasporangia bearing columnar cap walls (i.e., conceptacles multiporate), roof exposed by sloughing-off overlying epithallium; conceptacle cavity calcite, including surrounding and underlying perithallium dissolved by maturing sporangia; gametangia (where known) and carposporangia (where known) developing in uniporate conceptacles; roof of spermatangial conceptacles not reformed by lateral growing in of tissue, spermatangia produced from columnar cells clothing entire inner walls of conceptacles.

Information contributed by: Wm. J. Woelkerling & Paul W. Gabrielson. The most recent alteration to this page was made on 2024-02-23 by M.D. Guiry.

Taxonomic status: This name is of an entity that is currently accepted taxonomically.

Gender: This genus name is currently treated as neuter.

Most recent taxonomic treatment adopted: Adey, W.H., Hernández-Kantún, J.J., Johnson, G. & Gabrielson, P.W. (2015). DNA sequencing, anatomy, and calcification patterns support a monophyletic, subarctic, carbonate reef-forming Clathromorphum (Hapalidiaceae, Corallinales, Rhodophyta). Journal of Phycology 51(1): 189-203.


Information on the taxonomic history, nomenclature, and other matters associated with the name Clathromorphum is contained in Woelkerling (1988: 158-167). Growth form terminology (encrusting, lumpy, discoid, etc.) follows Woelkerling et al. (1993).

Adey et al. (2015) sequenced the lectotype and isolectotype specimens of C. compactum (Kjellman) Foslie, the lectotype species of Clathromorphum. Additional data on the lectotype specimen is provided in Woelkerling (1988: 161-163, figs 167-170) (also see Woelkerling et al. 2005: 488).

Adey et al. (2015) question the inclusion of all southern hemisphere species of Clathromorphum in the genus; they also transferred C. loculosum to Neopolyporolithon and C. parcum to a new genus Callilithophytum. Accounts of northern hemisphere species are provided by Adey (1965, north-western Atlantic), Lebednik (1977, north-western North America), Kloczcova (1996, eastern Russia), Perestkenko (1994, eastern Russia) and Yoshida & Baba (1998, Japan), while accounts of southern hemisphere species are provided by Chamberlain et al. (1995, South Africa), Mendoza & Cabioch (1985, Kerguelen and southern South America) and Mendoza et al. (1996, Tierra del Fuego). Male and female conceptacles and carposporophytes are unknown in the type species (C. compactum) and are poorly known (or unknown) in most other species.

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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.

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M.D. Guiry in Guiry, M.D. & Guiry, G.M. 23 February 2024. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 15 June 2024

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