Caulacanthus Kützing, 1843

Lectotype species: Caulacanthus ustulatus (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, [1]-142, [part 2:] 143-458, 1, err.], pls 1-80. Leipzig: F.A. Brockhaus.

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Type designated in: Agardh, 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.

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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.

Information contributed by: G.T. Kraft & M.D. Guiry. The most recent alteration to this page was made on 2017-01-20 by M.D. Guiry.

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

Most recent taxonomic treatment adopted: Kylin, H. (1956). Die Gattungen der Rhodophyceen. pp. i-xv, 1-673, 458 figs. Lund: C.W.K. Gleerups.

Comments: 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).

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. okamurae 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. Zuccarello, West & Rueness (2002) discuss the genus and its species and conclude that while there are moleculat differences between populations from the Atlantic and Pacific, distinguishing these morhologically is not possible.

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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. 20 January 2017. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 16 April 2024

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