TAXA OF LIFE
PHYLUM GLAUCOPHYTA

EUKARYA>ARCHAEPLASTIDA>RHODOPLANTAE>GLAUCOPHYTA

Glaucophyta (glau-KA-fa-ta) is formed from two Greek roots that mean blue-green (glauko -γλαυκο); and plant (phyto -φυτό).  The reference is to the blue-green color of the cyanelles.  Glaukos also was a Greek sea god.

INTRODUCTION TO THE GLAUCOPHYTA

All glaucophytes occur in freshwater, but are rarely observed.  They tend to be coccoid and occur in loose colonies formed by the persistent cell wall of the parent cell following division (Figure A).  When they form motile cells (Figure B), the flagella are heterodynamic and covered with mastigonemes.  The base of the flagellar apparatus is associated with a multilayered structure (MLS) and cruciate flagellar roots, characters also associated with the Praesinophyta (in the Viriviplantae).  

They are clearly blue-green and their plastids retain aspects of the primary cyanobacterial endosymbiont not seen in any other taxa (except an unrelated euglyphid amoeba or Cyanomonas).  Because the endosymbionts retain a thin murein wall and appear to be cyanobacterial, the plastids are usually called cyanelles (Figure C).  They have subsurface sacs, a character that Patterson (1999) listed as an identifying synapomorphy.  If these sacs are alveoli, they might destroy the defining synapomorphy of the Alveolatae. 

SYSTEMATICS OF THE GLAUCOPHYTA

Moreira et al. (2000) and recent supertree analyses (Baldauf 2003; Keeling 2004; and Nikolaev et al. 2004) confirm the monophyly of the three groups.  Cavalier-Smith (2002, 2003) interprets the Rhodophytes and Viridiplantae as sister groups while the Glaucophytes are outgroups within the Plant clade.  Other analyses (Bhattacharya et al. 1995 and Nikolaev et al. 2004) showed them to be very different from the viridiplantae+rhodophytae.  Patterson (1999) includes the glaucophytes in his list of sisterless taxa, but includes Cyanidium in that group.

In the past they have been classified with the cryptophytes (Bourrelly 1970; Moestrup 1982), the chlorophytes (Bourrelly 1966), rhodophytes (Schnepf and Brown 1971; Cavalier-Smith 1982, 1986; Melkonian 1984), and the chlorophytes+euglenophytes (Moestrup 1982; Melkonian 1982, 1983; Kies and Kremer 1990).  Since 1990, the group has been classified independently (e.g. Kies and Kremer 1990; Patterson 1999; Graham and Wilcox 2000; Van den Hoek et al. 1995, and Lee 1999).  Clearly, these taxa hold uncertain status within the plants, the primary photosymbionts.

glaucocystis-conncoll.jpg (68494 bytes)

A. Glaucocystis, a coccoid taxon.

cyanophora_bgw-mbl.jpg (13825 bytes)

B. A motile cell of Cyanophora.  Note the heterodynamic flagella. 

glaucosphaera-uni-hamburg.jpg (34944 bytes)

C. A TEM micrograph of Glaucosphaera that shows the cyanobacterial nature of the cyanelles.

Images taken from:
A: http://silicasecchidisk.conncoll.edu/LucidKeys/Carolina_Key/html/Glaucocystis_Main.html
B: http://microscope.mbl.edu/baypaul/microscope/images/t_imgAZ/cyanophora_bgw.jpg
C: http://www.biologie.uni-hamburg.de/b-online/d42/10.htm

SYNOPTIC DESCRIPTION OF THE GLAUCOPHYTA

The description of this phylum comes from Bold and Wynne (1985), Van den Hoek et al. (1995), Graham and Wilcox (2000), Kies and Kremer (1990), and Patterson (1999).

I. SYNONYMS: glaucophytes.

II. NUMBER: >13 species (9? genera).

III. PHYLUM CHARACTERISTICS:

A. Structure and Physiology

Cell Form: Unicellular and loose colonies.

Flagella: 2 unequal flagella present in most with mastingonemes, inserted subapically; 9+0 pseudocilia in some.

Basal Bodies: Present; with a multi-layered structure (MLS) and cruciate flagellar roots.

Cell Covering: Covered by a thick proteinaceous cell wall.

Chloroplasts: Numerous coccoid cyanelles, dominated by blue-green phycobillins; with chlorophyll a, B-carotene, xanthophylls. 

Food Reserves: True starch free in the cytoplasm.

Mitochondria: Plate-like cristae.

Golgi: Present and associated with the basal bodies and/or the nucleus.

Nucleus: Uninucleate.

Centrioles: Not present.

Inclusions and Ejectile Organelles: Pulsating vacuole.

B. Mitosis, Meiosis and Life History

Mitosis: Open; division by infurrowing.

Meiosis: Not known.

Sexual Reproduction and Life History: Not known.

C. Ecology: Mainly found in fresh water habitats; rare.

HIERARCHICAL CLASSIFICATION OF THE GLAUCOPHYTA

This is a modification of Kies and Kremer (1990) and Lee (1999).

CLASS GLAUCOCYSTOPHYCEAE

ORDER GLAUCOSYSTIDALES

Glaucocystis, Cyanophora, Gloeochaete, Glaucosphaera.

LITERATURE CITED

Baldauf, S. L. 2003a. The deep roots of eukaryotes. Science. 300 (5626): 1701-1703. 

Bhattacharya, D. T., T. Helmchen, C. Bibeau, and M. Melkonian. 1995a. Comparison of Nuclear-Encoded Small Subunit Ribosomal RNAs Reveal the Evolutionary Position of the Glaucocystophyta. Molecular Biology and Evolution. 12: 415-420.

Bold, H. C. and M. J. Wynne. 1985. Introduction to the Algae. 2nd Edition. Prentice-Hall, Inc. Englewood Cliffs. NJ.

Bourrelly, P., 1966. Les Algues d'eau Douce. Initiation à la sistematique I. Les Algues Vertes. N. Boubèe, Paris. 511pp.

Bourrelly, P., 1970. Les Algues d'eau Douce. Initiation à la sistematique III. Les algues bleus et rouges, les Eugléniens, Péridiniens et Cryptomonadines. N. Boubée, Paris. 512pp.

Cavalier-Smith, T. 1982. The origins of plastids. Biological Journal of the Linnaean Society. 17: 289-306.

Cavalier-Smith, T. 1986a. The kingdom Chromista: origin and systematics. In: F. E. Round and D. J. Chapman, eds. Progress in Phycological Research.  BioPress Ltd. Bristol, UK. vol. 4, 309–347.

Cavalier-Smith, T. 2002a. The phagotrophic origin of eukaryotes and phylogenetic classification of Protozoa. International  Journal of Systematic Evolutionary Microbiology. 52:297–354. 

Cavalier-Smith, T. 2003c. Genomic reduction and evolution of novel genetic membranes and protein-targeting machinery in eukaryote-eukaryote chimaeras (meta-algae). Philosophical Transactions of the Royal Society of London B. 258:109-134.

Graham, L. E., and L. W. Wilcox. 2000. Algae. Prentice Hall, Upper Saddle River, NJ.

Keeling P. J. 2004 The diversity and evolutionary history of plastids and their hosts. American Journal of Botany. 91(10): 1481-1493. 

Kies L. and B. P. Kremer. 1990. Phylum Glaucocystophyta. In: Margulis L., J. O. Corliss, M. Melkonian, and D. J. Chapman, eds. Handbook of Protoctista. Jones and Bartlett, Boston, pp 152—166. [L]

Lee, R. E. 1999, Phycology: 3rd ed., CambridgeUniversity Press, Cambridge, UK .

Melkonian, M. 1982. Structural and evolutionary aspects of the flagellar apparatus in green algae and land plants. Taxon. 31: 255-265.

Melkonian, M. 1983. Evolution of green algae in relation to endosymbiosis. In: Schenk, H. E. A. and W. Schwemmler, eds. Endocytobiology II.   De Gruyter. Berlin-New York. pp. 1003-1007.

Melkonian, M. 1984. Flagellar apparatus ultrastructure in relation to green algal classification. In: Irvine, D. E. G. and D. M. John, eds. Systematics of the Green Algae. Academic Press. London/Orlando. pp. 73-120.

Moestrup Ø. 1982. Flagellar structure in algae: a review, with new observations paricularly on the Chrysophyceae, Phaeophyceae (Fucophyceae),  Euglenophyceae, and Reckertia. Phycologia. 21: 427-528.

Moreira, D., H. le Guyader, and H. Phillippe. 2000. The origin of red algae and the evolution of chloroplasts. Nature. 405: 69-72.

Nikolaev, S. I., A. P. Milnikov, C. Berney, J. Fahrni, J. Pawlowsli, V. V. Aleshin, and N. B. Petrov. 2004. Molecular phylogenetic analysis places Percolomonas cosmopolitus within Heterolobosea: evolutionary implications. Journal of Evolutionary Microbiology. 51(5): 575-581. 

Patterson, D. J. 1999. The diversity of eukaryotes. American Naturalist. 154 (Suppl.): S96–S124.

Schnepf, E. and R. M. Brown, Jr. 1971.  On relationships between endosymbiosis and the origin of plastids and mitochondria. In: J. Reinert and H. Ursprung, eds. Origin and Continuity of Cell Organelles. Springer-Verlag. Berlin, Heidelberg, New York. .pp. 299-322.

Van Den Hoek, C., D. G. Mann, and H. M. Jahns. 1995. Algae, An Introduction to Phycology. Cambridge University Press.  Cambridge.

By Jack R. Holt.  Last revised: 03/21/2010