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Chroomonas | Komma

Kerstin Hoef-Emden and John M. Archibald
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Containing group: Cryptomonads



Discussion of Phylogenetic Relationships

Blue-green cryptophytes with hexagonal periplast plates and with a pointed antapex bent towards the ventral side have been separated from Chroomonas (staggered rectangular plates) as the genus Komma. Some Chroomonas species are considered of uncertain status because they contain phycocyanin 630 (absorption maxima at 630 and 583 nm).

In molecular phylogenies, the genus Chroomonas is split up in two clades with Hemiselmis evolving from between the two (Figure 1). The sister clade to Hemiselmis is further subdivided into three clades. By genetic divergence each of the four Chroomonas clades may be considered a separate genus (Hoef-Emden 2008). An examination of the type material of Chroomonas nordstedtii Hansgirg by scanning electron microscopy showed that the current definition of the genus Chroomonas may be wrong. The type material contained elliptical cells with hexagonal periplast plates (Novarino 2003).

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Figure 1. Molecular phylogeny of the genera Chroomonas, Hemiselmis and Komma. Maximum likelihood tree inferred from nucleomorph SSU rDNA sequences. PC, phycocyanin; PE, phycoerythrin; scale bar = substitutions per site. © 2008 Kerstin Hoef-Emden


Hansgirg A (1885) Anhang zu meiner Abhandlung „Ueber den Polymorphismus der Algen“. Bot. Zentralbl. 23: 229-233

Hill DRA (1991b) Chroomonas and other blue-green cryptomonads. J. Phycol. 27: 133-145

Santore UJ (1984) Some aspects of taxonomy in the Cryptophyceae. New Phytol. 98: 627-646

Hoef-Emden K (2008) Molecular phylogeny of phycocyanin-containing cryptophytes: Evolution of biliproteins and geographical distribution. J. Phycol. 44: 985-993

Novarino G (2003) A companion to the identification of cryptomonad flagellates (Cryptophyceae = Cryptomonadea). Hydrobiologia 502: 225-270

Title Illustrations
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Scientific Name This may be Chroomonas mesostigmata
Location material from Provasoli-Guillard National Center for Culture of Marine Phytoplankton
Source Chroomonas
Source Collection Micro*scope
Image Use creative commons This media file is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike License - Version 2.5.
Copyright © Bob Andersen and D. J. Patterson
About This Page

This page is being developed as part of the Tree of Life Web Project Protist Diversity Workshop, co-sponsored by the Canadian Institute for Advanced Research (CIFAR) program in Integrated Microbial Biodiversity and the Tula Foundation.

Kerstin Hoef-Emden
Universität zu Köln, Köln, Germany

John M. Archibald
Dalhousie University, Halifax, Nova Scotia, Canada

Correspondence regarding this page should be directed to Kerstin Hoef-Emden at and John M. Archibald at

Page: Tree of Life Chroomonas | Komma. Authored by Kerstin Hoef-Emden and John M. Archibald. The TEXT of this page is licensed under the Creative Commons Attribution-NonCommercial License - Version 3.0. Note that images and other media featured on this page are each governed by their own license, and they may or may not be available for reuse. Click on an image or a media link to access the media data window, which provides the relevant licensing information. For the general terms and conditions of ToL material reuse and redistribution, please see the Tree of Life Copyright Policies.

Citing this page:

Hoef-Emden, Kerstin and John M. Archibald. 2008. Chroomonas | Komma. Version 14 September 2008 (under construction). http://tolweb.org/Chroomonas_%7C_Komma/128542/2008.09.14 in The Tree of Life Web Project, http://tolweb.org/

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