Sporolithon Heydrich, 1897
Holotype species: Sporolithon ptychoides Heydrich
Original publication and holotype designation: Heydrich, F. (1897). Corallinaceae, insbesondere Melobesieae. Berichte der deutsche botanischen Gesellschaft 15: 34-70, 3 figs, pl. III.
Request PDFDescription: Thalli comprising dorsiventral crusts to masses of protuberances; attached or unattached. Haustoria lacking. Organized into first-order filaments only (monomerous); filaments not arranged in decumbent, arching tiers of cells (coaxial anatomy), instead curving toward thallus surface (plumose anatomy). Outermost walls of epithallial cells flattened and flared. Cells in contiguous filaments often joined by fusions; secondary pit-connections sometimes present, but not predominant. Trichocytes lacking.Reproductive cells forming among filaments below plant surface; in conceptacles in sexual plants. Tetrasporangia and bisporangia in diffuse fields, not clearly delimited, with groups of calcified filaments occurring among the sporangia. Each tetrasporangium or bisporangium forming an apical plug which occupies a space in roof directly above sporangium; tetrasporangia usually zonate, sometimes cruciate; bisporangia rare. Gametangia poorly known.
Information contributed by: H.W. Johansen. The most recent alteration to this page was made on 2018-11-11 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: 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.
Comments: Sporolithon has often been incorrectly reported as Archaeolithothamnion (or Archaeolithothamnium). The genus is well represented in the fossil record. The configuration of tetrasporangium-producing areas has been debated. Unlike Lithothamnion, the sporangia are not produced within chambers that are discrete at maturity. Instead, the sporangia occur in fields (that have been called sori) where they are separated from one another by calcified filaments growing toward the thallus surface. These calcified filaments appear to be homologous to uncalcified filaments occurring among young tetrasporangia in Lithothamnion. Reports of bisporangia may be based on improperly interpreted cruciate tetrasporangia. Sporolithon is the only genus in which the latter occur; it appears as if they are not common. Sporolithonand Lithothamnionare closely related; they are the only coralline genera in which the outer epithallial cell walls are flat and flared. These two genera also have single orders of filaments and tetrasporangia (and bisporangia) with apical plugs. Sporolithon differs from Lithothamnion in having occasional secondary pit-connections plus cell fusions, persistent calcified filaments among the tetrasporangia, and occasional cruciate tetrasporangia.
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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.
Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=34628
Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 11 November 2018. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 22 November 2024
