Mallomonas Perty, 1852
Holotype species: Mallomonas ploesslii Perty
Original publication and holotype designation: Perty, M. (1852). Zur Kenntniss kleinster Lebensformen: nach Bau, Funktionen, Systematik, mit Specialverzeichniss der in der Schweiz beobachteten. pp. 1-228, pls I-XVII. Bern: Verlag von Jent & Reinert.
Taxonomic status: currently recognized as a distinct genus.
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.
Some authors name Mallomonas acaroides Perty as the generitype, but
Description: Cells solitary, surrounded by an envelope of silica scales. Scales consist of a perforated basal plate, often overlain by secondary patterns. In most species some or all scales bear silica bristles. In the species considered most primitive (section Mallomonopsis, etc.), scales without or only with scant secondary structures. In most species (section Mallomonas and others), scales are tripartite, comprising a dome, shield and flange. Usually a distinct succession of scale types occurs: collar scales (often asymmetric), domed body scales, domeless body scales, and tail scales (often spine bearing). Bristles either glued to the scale (primitive species), or articulated by a special foot in the concavity of the dome (when present). Bristles are tubular with a longitudinal slit, smooth or serrated, the tips may be intricately shaped. Several types of bristles may occur in one cell and may be environmentally determined. In species considered primitive the serration is on the edge, along the slit: craspedodont. Advanced species have teeth not along the edge but as hollow bulges from the opposite side: notacanthic. Both scales and bristles form inside the cell. Vesicles form on the outer side of the chloroplast as bulges from the chloroplast ER. They fuse with Golgi vesicles and are cut off and serve as deposition and molding vesicles for scales and bristles. These begin as flat elements and then roll up into shape. After completion, they are extruded from the cell and arranged in the definite imbricate pattern on the cell surface. Scales and bristles apparently form independently and combine only after extrusion. Cell biflagellate, but in most species, except the subgenus Mallomonopsis, the smooth flagellum is reduced to a short stump not visible by light microscopy. It bears a swelling thought to be a photoreceptor. The hairy flagellum has 2 rows of tripartite hairs and in a few species has been shown to be covered with small annular scales. Flagella have parallel basal bodies and emanate from a flagellar pit. By means of a well-developed rhizoplast they are connected to the outer nuclear membrane. Each cell contains a bilobed chloroplast without stigma. In front of the nucleus a large Golgi, behind a chrysolaminaran vacuole. Asexual reproduction by longitudinal division, during which process the cell covering is reestablished. Sexual reproduction, known in a few species, is isogamous with lateral or caudal fusion. Zygotes develop silicified walls. Germination not observed. Stomatocysts observed in about half the species, spherical or ovoid, and the porus sometimes surrounded by a collar. Surface is smooth or has a species-specific ornamentation. Stomatocyst formation has been followed in M. caudata. The silica wall is deposited endogenously, leaving some protoplasm outside. The porus is formed secondarily and then closed with a plug. The cyst is uni-nucleate, with a large chrysolaminaran vesicle and lipid droplets. Based on scale and bristle ultrastructure the genus has been divided into 17 sections and a total of almost 120 species. Many species described before EM cannot be recognized because theirscale structure is unknown, but in several cases it has been possible to harmonize microscopically described species with EM based taxonomy. Silicified Mallomonas cysts and scales often preserve well in lake sediments. This and recent knowledge of the ecology of Mallomonas spp. have been combined toward reconstruction of lake history, especially as regards eutrophication and acidification. Stomatocysts are better preserved than scales, but only a few can be referred to species. (Nygaard (1956), Sandgren and Carney (1983), Smol and others (1984). Common in plankton of freshwater bodies; a few are brackish. Nearly worldwide distribution.
Information contributed by: J. Kristiansen. The most recent alteration to this page was made on 7 Mar 2017 by M.D. Guiry.
Numbers of names and species: There are 264 species names in the database at present, as well as 104 infraspecific names. Of the species names, 231 have been flagged as accepted taxonomically on the basis of the listed literature under the species name. In some instances, opinions on taxonomic validity differ from author to author and users are encouraged to form their own opinion. AlgaeBase is a work in progress and should not be regarded as a definitive source only as a guide to the literature..
Names: ('C' indicates a name that is accepted taxonomically; 'S' a homotypic or heterotypic synonym; 'U' indicates a name of uncertain taxonomic status, but which has been subjected to some verification nomenclaturally; 'P' indicates a preliminary AlgaeBase entry that has not been subjected to any kind of verification. For more information on a species click on it to activate a link to the Species database):
Click here to also show infraspecific names in the list below.
Kristiansen, J. & Preisig, H.R. (2001). Encyclopedia of Chrysophyte genera. Bibliotheca Phycologica 110: 1-260.
Siver, P.A. (2003). Synurophyte Algae. In: Freshwater Algae of North America, Ecology and Classification. (Wehr, J.D. & Sheath, R.G. Eds), pp. 523-558. San Diego: Academic Press.
Jo, B.Y., Shin, W., Boo, S.M., Kim, H.S. & Siver, P.A. (2011). Studies on ultrastructure and three-gene phylogeny of the genus Mallomonas (Synurophyceae). Journal of Phycology 47(2): 415-425.
Asmund, B. & Kristiansen, J. (1986). The genus Mallomonas. (Chrysophyceae). A taxonomic survey based on the ultrastructure of silica scales and bristles. Opera Botanica 85: 1-128, 72 figs., portrait [of Berit Asmund 1904-1985], 3 tables.
Verification of data
Users are responsible for verifying the accuracy of information before use, as noted on the website Content page.
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.
Created: 11 April 2002 by M.D. Guiry
Verified by: 07 March 2017 by M.D. Guiry
Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=43803
Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2019. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 23 April 2019.