Geminella Turpin, 1828

Holotype species: Geminella interrupta Turpin

Original publication and holotype designation: Turpin, P.J.F. (1828). De la description de plusieurs genres et espèces nouvelles très remarquables, découverte parmi les productions végétales et microscopiques. Mémoires du Musée d'Histoire Naturelle 16: 295-344, pl. 13 ["15"].

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Description: Free-floating or sessile filaments surrounded by homogeneous mucilaginous envelope of considerable thickness, without polar differentiation. Filaments uniseriate, of different length. Individual cells dispersed in loose linear arrangement, equidistant, or in pairs, or cells united end to end, slightly meeting at poles. Cells basically cylindrical and elongated with broadly rounded ends, sometimes slightly inflated and ellipsoid to oval. Chloroplasts single and parietal, girdle-shaped or laminate, often restricted to equatorial cell region and partially encircling protoplast, with one central pyrenoid. Propagation via fragmentation of filaments. Infrequent cleavage in several directions leading to irregular accumulations of cells finally discharged from parental filament following disintegration of common mucilaginous wall. Zoospores not definitely known. Akinetes with thick brown walls. Method of sexual reproduction unknown. Geminella cosmopolitan, mostly planktonic in various freshwater habitats including swamps and shallow waters of lakes and ponds; also reported from periphyton of Lemna and from terrestrial habitats. The close resemblance of Geminella to other (pseudo)filamentous genera also equipped with mucilaginous sheath surrounding filaments precludes an explicit taxonomic delimitation. In addition, extensive comparative light and electron microscopic studies are required to clarify species delimitation.

Information contributed by: G.M. Lokhorst. The most recent alteration to this page was made on 2012-04-27 by Michael Guiry.

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

Most recent taxonomic treatment adopted: Tsarenko, P.M. (2011). Trebouxiophyceae. In: Algae of Ukraine: diversity, nomenclature, taxonomy, ecology and geography. Volume 3: Chlorophyta. (Tsarenko, P.M., Wasser, S.P. & Nevo, E. Eds), pp. 61-108. Ruggell: A.R.A. Gantner Verlag K.-G..

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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in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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Michael Guiry in Guiry, M.D. & Guiry, G.M. 27 April 2012. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 24 April 2024

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