Spongomorpha Kützing, 1843
Holotype species: Spongomorpha congregata (C.Agardh) Kützing
Currently accepted name for the type species: Spongomorpha aeruginosa (Linnaeus) Hoek
Original publication: 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, -142, [part 2:] 143-458, 1, err.], pls 1-80. Leipzig: F.A. Brockhaus.
Type designated in: Setchell, W.A. & Gardner, N.L. (1920). The marine algae of the Pacific coast of North America. Part II. Chlorophyceae. University of California Publications in Botany 8: 139-374, pls 9-33.
Description: Plants forming green pompoms (gametophytes), up to 2 cm high, composed of slender (20-30 um), uniseriate branched filaments, attached by descending, often branched, multicellular rhizoids. Branches spreading in young plants, intertwined in older plants, forming secondary tufts. Branching intercalary, irregular, usually single per node, arising subterminally from upper cell pole with oblique crosswall at axial cell. Branches with rounded tips, rarely hooked. Thallus composed of short intercalary, sometimes isodiametric cells in the lower parts of the thallus, and longer cells in the upper part. Cells strictly uninucleate. Chloroplast single per cell, parietal, perforate, becoming dense toward tip in vigorously growing apical cells. Pyrenoids several per cell, polypyramidal, the matrix penetrated by tubules of chloroplast stroma. Plasmodesmata in crosswalls. Life history heteromorphic and haplodiplontic. Gametophytes unisexual (n = 6-7 chromosomes) and gametes isogamous or slightly anisogamous. Induction of gametogenesis correlated with longday conditions and cessation of growth from 5-150C. Gametes arise by sequential cleavage of cell contents. Gametangia located in long rows in middle region of thallus. Gamete liberation through circular non-crenulate pore in upper part of cell, provided with an operculum which is generally shed. Gametes enclosed within a vacuole sometimes released without dissolution. Gametes pear-shaped and biflagellate with one chloroplast containing a single pyrenoid and a distinct double layered eyespot. Flagellar apparatus with cruciately arranged microtubules. Root formula X-2-X-2, where X=3. EM studies of flagellar apparatus incomplete. Zygotes develop into a unicellular and uninucleate sporophyte, formerly described as Chlorochytrium inclusum Kjellman and Codiolum petrocelidis Kückuck, endophytes in various foliose and crustose algae. Sporophytes, either stalked (Codiolum) or stalkless (Chlorochytrium), depending upon the non-specific host plant, and is of no taxonomic value. In culture, induction of sporogenesis favored by presence of filamentous mother plants. Sporophytes produce quadriflagellate, ovoid zoospores, probably following meiosis that produce new filamentous gametophytes. Parthenogenetic gametes or zoospores in filamentous phase not observed, however, "false" zygotes may be produced, when nuclear fusion is suppressed after plasmogamy as in Acrosiphonia; these do not develop into unicellular sporophytes but into filamentous haploid plants. Spongomorpha distributed in temperate, cold temperate to arctic waters of North Atlantic and adjacent waters, growing in eulittoral zone, often in rock pools or epiphytically on larger algae. Spongomorpha aeruginosa also in the Baltic in salinities to 6.5 0/00. Spongomorpha unknown from Pacific. Growth limited to apical cells. Elongation of filaments may reach 0.6 mm per day, after two successive divisions of apical cells. Such divisions are restricted to the dark phase. Apical cell division gives rise to unequal cells, a new apical cell, a subapical cell which is much longer (sometimes 25), depending upon age and environmental conditions. Intercalary cell division occurs, but no cell elongation. Nucleus in apical cell migrates to future zone of cell division. Nucleus in apical cells more conspicuous (10-12 um in diameter with large nucleolus) than in intercalary cells. Cleavage furrow visible with light microscope during mitosis. No ultrastructural details available on mitosis and cytokinesis. Cell wall thin in fast growing plants, pecto-cellulosic in nature. Chemical composition unknown. X-ray diagrams somewhat different from Urosporaand Acrosiphonia, although indicating randomly arranged substances. Some authors merge Spongomorpha and Acrosiphonia based on common vegetative characters; however, nuclear number provides a stable feature for generic distinction.The most recent alteration to this page was made on 2021-10-20 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 feminine.
Most recent taxonomic treatment adopted: Gabrielson, P.W., Lindstrom, S.C. & O'Kelly, C.J. (2012). Keys to the seaweeds and seagrasses of Southeast Alaska, British Columbia, Washington, and Oregon. Phycological Contribution No. 8. pp. [i]-iv, 1-192. Hillsborough, North Carolina: PhycoID.
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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.
Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=32803
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 20 October 2021. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 25 March 2023