Asterococcus Scherffel, 1908

Holotype species: Asterococcus superbus (Cienkowski) Scherffel

Original publication and holotype designation: Scherffel, A. (1908). Asterococcus n. g. superbus ( Cienk.) Scherffel und dessen angebliche Bezeichnungen zu Eremosphaera. Berichte der Deutschen Botanischen Gesellschaft 26A: 762-771.

Description: Thalli occasionally unicellular, usually cells united into 2-4-8-16-64-celled colonies with cells embedded in conspicuous, and either lamellated or homogeneous mucilaginous envelope. Colonies spherical to amorphous with cells dispersed in envelope or cells terminal in branched mucilaginous material. Cells spherical to ellipsoidal, 10-40 &m diameter, with smooth cell walls. Cells uninucleate, usually with two persistent contractile vacuoles. Single chloroplast stellate with numerous arms radiating from central prominent pyrenoid to form discoid to elongate lobes at cell periphery. Asexual reproduction by aplanospores or zoospores; 2-8 per sporangium; released by dissolution of parental cell wall. Vegetative cells released from parental colony before or after production of flagella. Zoospores biflagellate, with stigma. Sexual reproduction unknown. Asterococcus planktonic or benthic in freshwater; reported from Europe and North America. Both species available from culture collections. Species distinguished based on habitat and details of mucilage stratification, chloroplast morphology and cell size. Five additional species have been described in Asterococcus but these have been synonymized within Asterococcus or are currently considered in Sphaerellocystis, Trochiscia, Spongiochloris or Actinochloris. Ultrastructural studies required to clarify relationships within family and order. Thalli occasionally unicellular, usually cells united into 2-4-8-16-64-celled colonies with cells embedded in conspicuous, and either lamellated or homogeneous mucilaginous envelope. Colonies spherical to amorphous with cells dispersed in envelope or cells terminal in branched mucilaginous material. Cells spherical to ellipsoidal, 10-40 &m diameter, with smooth cell walls. Cells uninucleate, usually with two persistent contractile vacuoles. Single chloroplast stellate with numerous arms radiating from central prominent pyrenoid to form discoid to elongate lobes at cell periphery. Asexual reproduction by aplanospores or zoospores; 2-8 per sporangium; released by dissolution of parental cell wall. Vegetative cells released from parental colony before or after production of flagella. Zoospores biflagellate, with stigma. Sexual reproduction unknown. Asterococcus planktonic or benthic in freshwater; reported from Europe and North America. Both species available from culture collections. Species distinguished based on habitat and details of mucilage stratification, chloroplast morphology and cell size. Five additional species have been described in Asterococcus but these have been synonymized within Asterococcus or are currently considered in Sphaerellocystis, Trochiscia, Spongiochloris or Actinochloris. Ultrastructural studies required to clarify relationships within family and order.

Information contributed by: D. Garbary & A. Couté. The most recent alteration to this page was made on 2012-04-01 by M.D. Guiry.

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

Most recent taxonomic treatment adopted: Masjuk, N.P. & Lilitska, G.G. (2011). Volvocales. In: Algae of Ukraine: diversity, nomenclature, taxonomy, ecology and geography. Volume 3: Chlorophyta. (Tsarenko, P.M., Wasser, S.P. & Nevo, E. Eds), pp. 218-225. 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=43405

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 01 April 2012. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 23 November 2024