Mesostigma Lauterborn, 1894
Holotype species: Mesostigma viride Lauterborn
Original publication and holotype designation: Lauterborn, R. (1894). Ueber die Winterfauna einiger Gewässer der Oberrheinebene. Mit Beschreibungen neuer Protozoen. Biologische Centralblatt 14: 390-398.
Taxonomic status: currently recognized as a distinct genus.
Most recent taxonomic treatment adopted: Marin, B. & Melkonian, M. (1999). Mesostigmatophyceae, a new class of streptophyte green algae revealed by SSU rRNA sequence comparisons. Protist 150: 399-417, 9 figs, 2 tables.
Description: Flat to saddle-shaped flagellates with 2 flagella emerging from a pit in the convex dorsal side. The ventral side somewhat concave. The flagellar pit is located near the front end, and the flagella are directed more or less anteriorly in the swimming cell which rotates rapidly during swimming. A single parietal chloroplast covers the ventral and lateral sides and extends onto the dorsal side. A single eyespot on the ventral side, near the mid axis of the cell. Several contractile vacuoles near the flagellar bases. Two pyrenoids present in the type species, while the other species lacks pyrenoids. The cell and flagella covered with several types of scales. Scales of the outermost layer on the cell body are sufficiently large to be visible under the light microscope. Two additional layers of scales present in M. viride. The flagella of M. viride covered with a single type of scales, while hair-shaped scales appear to be lacking. Sexual reproduction unknown. This remarkable genus of prasinophytes occurs in many types of fresh water. The two species differ in size and in the presence/absence of pyrenoids. Ultrastructural studies on Mesostigma viride were published by Manton and Ettl (1965) and, more recently, by Rogers and others (1981) and Melkonian (1989), with emphasis on the structure of the flagellar apparatus. Mesostigma is phylogenetically most closely related to Pyramimonas, but its many unique features make it one of the most distinct prasinophycean flagellates. For a taxonomic treatment, see Ettl (1983).
Information contributed by: Ø. Moestrup. The most recent alteration to this page was made on 27 Oct 2012 by M.D. Guiry.
Numbers of names and species: There are 2 species names in the database at present, of which 1 has 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.
Sluiman, H.J., Guihal, C. & Mudimu, O. (2008). Assessing phylogenetic affinities and species delimitations in Klebsormidiales (Streptophyta): nuclear-encoded rDNA phylogenies and ITS secondary structure models in Klebsormidium, Hormidiella, and Entransia. Journal of Phycology 44(1): 183-195.
Marin, B. & Melkonian, M. (1999). Mesostigmatophyceae, a new class of streptophyte green algae revealed by SSU rRNA sequence comparisons. Protist 150: 399-417, 9 figs, 2 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: 23 April 2002 by M.D. Guiry
Verified by: 28 June 2012 by Michael Guiry
Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=44216
Please cite this record as:
Michael 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 January 2019.