Caulacanthus Kützing, 1843: 395
Lectotype species: Caulacanthus ustulatus (Mertens ex Turner) Kützing
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 inAgardh, J.G. (1851). Species genera et ordines algarum, seu descriptiones succinctae specierum, generum et ordinum, quibus algarum regnum constituitur. Volumen secundum: algas florideas complectens. Part 2, fasc. 1. pp. 337 [bis]-351 [bis] 352-506. Lundae [Lund]: C.W.K. Gleerup.
Taxonomic status: currently recognized as a distinct genus.
Description: Plants typically form low tangled clumps of terete erect and prostrate axes up to 3 cm high, the axes attached by numerous scattered holdfast pads. Each central axial cell cuts off 2 periaxial cells. Carpogonial branches are 3-celled and directed toward the thallus surface. Connecting filaments are single and short from fertilized carpogonia. Gonimoblasts develop toward the thallus interior initially, then come to radiate from a large central fusion cell incorporating several cells of the central axial filament of the fertile lateral spine or branchlet. Searles (1968) reports that several gonimoblast initials are formed, although Min-Thein and Womersley (1976) suspect that this may result from early incorporation of a single gonimoblast initial into the fusion cell. Carposporangia are single and terminal; cystocarps are embedded in distal axes and have a single ostiole formed by localized separation of cortical filaments. Spermatangia form in extensive sori near branch tips of monoecious gametophytes, whereas tetrasporangia are scattered. The morphology of the type species is detailed by Searles (1968), with further comments on recent taxonomic activity being given by Norris and Wynne (1968).
Comments: Distribution: The type species is widely distributed in the Mediterranean Sea, Africa, and western Pacific Oceans, western North America, Australia and New Zealand. According to Searles (1968) it is questionably distinct from C. okamurai Yamada from Japan and apparently differs indicus Weber-van Bosse (Malaysia) in lacking a dimorphism between sterile and tetrasporangium-bearing parts of sporophytic fronds. Searles (1968) suggests that its wide occurrence may be its physiological resilience, as indicated by its exclusively intertidal habitats. Chapman (1950) calls attention to interesting ring-like configurations of Caulacanthus populations associated with mussel beds. Caulacanthus salifugus Cribb (1965) is based on sterile material growing with moss and Oedogonium sp. in a Queensland seml-marine cavern.
Numbers of names and species: There are 12 species (and infraspecific) names in the database at present, of which 3 have been flagged as currently accepted taxonomically.
Names: ('C' indicates a name that is currently 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):
Caulacanthus compressus Harvey S
Caulacanthus divaricatus (Suhr) Papenfuss S
Caulacanthus fastigatus Kützing S
Caulacanthus horridulus Montagne S
Caulacanthus indicus Weber-van Bosse S
Caulacanthus okamurae Yamada C
Caulacanthus rayssiae Feldmann & G.Feldmann S
Caulacanthus rigidus Kützing C
Caulacanthus salifugus A.B.Cribb C
Caulacanthus spinellus (J.D.Hooker & Harvey) Kützing S
Caulacanthus ustulatus var. fastigiatus (Kützing) Pilger C
Caulacanthus ustulatus (Mertens ex Turner) Kützing C - type
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: http://www.algaebase.org/search/genus/detail/?genus_id=33244
Cite this record as:
Guiry, M.D. & Guiry, G.M. 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 19 June 2013.
Algaebase taxon LSID: urn:lsid:algaebase.org:taxname:8261