Characium A.Braun, 1849

Lectotype species: Characium sieboldii A.Braun

Original publication: Kützing, F.T. (1849). Species algarum. pp. [i]-vi, [1]-922. Lipsiae [Leipzig]: F.A. Brockhaus.

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Description: Solitary, cylindrical, pyriform, ovoid, egg or spindle shaped or spherical cells. Cells often bent or asymmetrical and attached to substratum at one end by basal pad or with short to prominent stipes to 40 µm long; at opposite end cells rounded to pointed, with or without attenuate process. Cells 11-45 (- >100) x 8.5-23 µm, with smooth cell walls. Cells uninucleate; chloroplasts mostly single, parietal and band shaped; pyrenoids mostly single but up to eight reported, usually with distinct starch sheath. Asexual reproduction by biflagellate zoospores or akinetes; spores released through apex of cell or through tear in lateral wall. Zoospores 7-19 x 2-3 µm, with two equal, apical flagella and contractile vacuoles; chloroplast single and parietal with pyrenoid and stigma. Thick-walled, spherical akinetes to 100 µm present, often with accumulation of carotenoid pigments. Sexual reproduction reported for C. starrii, however, this species now referred to Chlamydopodium. Characium epiphytic on other algae and macrophytes, epilithic or epizoic in various freshwater habitats or soil in arctic to tropical climates. Genus cosmopolitan but some species reported with highly localized distributions. Species grow well in culture and various species available in culture from UTEX and NIES. Genus distinguished from Pseudocharacium which has quadriflagellate zoospores. Species distinguished based on features of cell size and shape, and nature of stipe. Species also differ in a variety of physiological criteria including ability to utilize various carbon sources and relative ability to grow under aerophilic and microaerophilic conditions in various environmental and chemical conditions. Sequence analyses of 18S rRNA for C. vacuolatum, C. hindakii and C. perforatum suggest relationships with Ettlia and Dunaliella, Neochloris and Pediastrum, and Parietochloris and Friedmannia, respectively, none of which are classified in Characiaceae. Results of molecular studies congruent with prior ultrastructural studies of zoospores with respects to flagellar apparatus and general cell structure. This suggests a polyphyletic Characium; however, assignment of these species to Characium equivocal. Hyalocharacium Pascher (1929) based on H. chrysopyxidis sometimes segregated from Characium (see Komárek and Fott 1983). This species appears to be a colorless and chloroplast-free form of Characium and it seems unnecessary to segregate Hyalocharacium based on this feature. Key

Information contributed by: D. Gargary & T. Kalina. The most recent alteration to this page was made on 2023-11-19 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: Tsarenko, P.M. (2011). Sphaeropleales. In: Algae of Ukraine: diversity, nomenclature, taxonomy, ecology and geography. Volume 3: Chlorophyta. (Tsarenko, P.M., Wasser, S.P. & Nevo, E. Eds), pp. 280-355. Ruggell: A.R.A. Gantner Verlag K.-G..

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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=37473

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 19 November 2023. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 22 November 2024