Synura Ehrenberg, 1834

Holotype species: Synura uvella Ehrenberg

Original publication and holotype designation: Ehrenberg, C.G. (1834). Dritter Beitrag zur Erkenntniss grosser Organisation in der Richtung des kleinsten Raumes. Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin 1833: 145-336, pls I-XIII.

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Description: Spherical or ovoid, free-swimming colonies with loosely associated pyriform cells united by their tails in the center of colony. Each cell surrounded by a covering consisting of imbricate silica scales, their ultrastructure primarily defining the species. A scale has a perforated basal plate with an upturned rim and in most species an apical spine or similar structure. Most species have secondary ornamentation consisting of struts or reticulation. Scales originate in vesicles on the outer side of the chloroplast and during genesis are molded into shape by outbulgings from the chloroplast endoplasmic reticulum. When finished, they are extruded from the cell and arranged in a definite pattern. (Schnepf and Deichgräber, 1979). The degree of ornamentation depends on the silica concentration in the ambient medium. (Sandgren and Barlow, 1989). Several scale types occur on the same cell, in a definite sequence - e. g. in S. spinosa 4 types: caudal scales, spineless body scales, spine-bearing body scales, and tubular apical scales. The cell has two flagella of almost equal length arising from an apical pit and with parallel basal bodies. The longer hairy flagellum beats in sinuous waves, whereas the smooth flagellum shows a stiffer beat. Small annular flagellar scales have been demonstrated, being formed in a special flagellar scale reservoir. (Hibberd, 1973). The flagellar root system comprises 4 microtubular roots, one looping around the flagella bases. This root is the nucleating site for the cytoskeletal microtubules. There are two yellow-brown chloroplasts on each side of the nucleus.Between them is the storage vesicle with chrysolaminaran - except in S. sphagnicola, where chrysolaminaran forms on the outer side of chloroplasts. Also in this species, each chloroplast has a pyrenoid, with an associated lamellar stack of unknown nature. No stigma, but the smooth flagellum has a flagellar swelling acting as a photoreceptor, and colonies are strongly phototactic. Several contractile vacuoles occur, mainly in the posterior part of the cell. (Hibberd, 1978). Asexual reproduction by longitudinal division of the cell is followed by reestablishment of scale cover. Cells also leave the scale cover and swim away. Also rhizopodial and palmella stages have been reported. Sexual reproduction has recently been observed; colonies are heterothallic; small male gametes released from one colony mate with female cells in another colony. Zygotes encyst, as stomatocysts. They are spherical, smooth, sometimes all the cells of a colony transform into cysts simultaneously. (Sandgren and Flanagin, 1986). Common in cold freshwater lakes and ponds. Mass development of Synura produces offensive, fishy-cucumber-like odors, sometimes a nuisance in drinking water supplies. (Nicholls and Gerrath, 1985). The volatile substances are an impressive array of amines and ketones. Synura species have diverse ecologies; some species arewidespread, others extremely rare and confined to special habitats. (Kristiansen, 1975).

Information contributed by: J. Kristiansen. The most recent alteration to this page was made on 2021-10-09 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 feminine.

Most recent taxonomic treatment adopted: Throndsen, J. (1996). The planktonic marine flagellates. In: Identifying marine phytoplankton. (Tomas, C.R. Eds), pp. 591-730. San Diego: Academic Press.

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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. 09 October 2021. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 17 June 2024

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