The Cyanobacteria and Their Taxonomy

After Rippka et al. (1979)

See also the older taxonomic scheme based on Stanier 1977

The paper by Rippka et al. 1979 contains many micrographs of cell morphologies typical of these genera.

SECTION I (Unicellular)

Unicellular cyanobacteria that reproduce by binary fission or by budding

unicellular cyanobacteria with cylindrical to ovoid cells that reproduce by binary transverse fission

• thylakoids present
• sheath absent

Gloeothece Nageli 1849

• thylakoids present
• sheath present

Gloeobacter Rippka, Waterbury & Cohen-Bazire 1974

• thylakoids absent
• sheath absent

unicellular cyanobacteria with spherical cells that divide in two or three successive planes at right angles to one another

• thylakoids present
• sheath absent

Gloeocapsa Kutzing 1843

• thylakoids present
• sheath present

unicellular cyanobacteria that reproduce by forming successive spherical buds from one pole of the ovoid cell

SECTION II (Unicellular)

Unicellular cyanobacteria that reproduce by multiple fission

reproduction only by multiple fission

• motile baeocytes

Xenococcus Thuret 1880

• immotile baeocytes

reproduction by both binary fission and multiple fission

• binary fission yields pear-shaped structure of one or two basal cells and one apical cell
• subsequent multiple fission of apical cell yields motile baeocytes

Myxosarcina Printz 1921

• binary fission yields cubical cellular aggregates
• subsequent multiple fission yields motile baeocytes

Chroococcidiopsis Geitler 1933

• binary fission yields cubical cellular aggregates
• subsequent multiple fission yields immotile baeocytes

Pleurocapsa group

• binary fission yields irregular cellular aggregates (pseudofilamentous)
• subsequent multiple fission yields motile baeocytes

SECTION III (Filamentous)

Filamentous non-heterocystous cyanobacteria that divide in only one plane

trichome helical

• cells in trichome isodiametric, cylindrical or disc-shaped
• little or no constriction between adjacent cells
• reproduction by transcellular trichome breakage
• trichome motile
• trichome not ensheathed or thinly ensheathed

trichome straight

• cells in trichome disc-shaped and not separated by deep constrictions
• reproduction by transcellular trichome breakage
• trichome motile, not ensheathed or thinly sheathed

LPP group A

• cells in trichome disc-shaped and not separated by deep constrictions
• reproduction by transcellular trichome breakage
• trichome immotile, enclosed by heavy sheath
• motility restricted to sheathless or thinly sheathed hormogonia

Pseudoanabaena Lauterborn 1915

• cells in trichome isodiametric or cylindrical
• deep constrictions between adjacent cells
• reproduction by transcellular or intercellular trichome breakage
• trichome motile, not ensheathed
• cells contain polar gas vesicles

LPP group B

• cells in trichome isodiametric or cylindrical
• variable degree of constriction between adjacent cells
• reproduction by transcellular or intercellular trichome breakage
• do not fit the entire description:
  • deep constrictions between adjacent cells
  • trichome motile, not ensheathed
  • cells contain polar gas vesicles
• may be with or without sheath, motile or immotile

SECTION IV (Filamentous)

Filamentous heterocystous cyanobacteria that divide in only one plane

reproduction by random trichome breakage; some germinate from akinetes; trichomes indistinguishable from mature vegatative trichomes

• heterocysts intercalary or terminal
• position of akinetes variable
• vegetative cells spherical, ovoid or cylindrical

Nodularia Mertens 1822

• heterocysts intercalary or terminal
• position of akinetes variable
• vegetative cells disc-shaped

Cylindrospermum Kutzing 1843

• heterocysts exclusively terminal and form at both ends of the trichome
• akinetes are always adjacent to heterocysts
• vegetative cells isodiametric or cylindrical

reproduction by random trichome breakage; some germinate from akinetes; form hormogonia distinguishable from mature trichomes by absence of heterocysts and one or more of the following characters: rapid gliding motility, smaller cell size, cell shape and gas vacuolation

• hormogonia give rise to young filaments with terminal heterocysts at both ends of the cellular chain
• vegetative cells spherical, ovoid or cylindrical
• akinetes (if produced) are not initiated adjacent to heterocysts and are often formed in chains

Scytonema Agardh 1824

• hormogonia give rise to young filaments with terminal heterocyst at only one end of the cellular chain
• mature trichome composed of cells of even width
• heterocysts predominantly intercalary
• vegetative cells disc-shaped, isodiametric or cylindrical

Calothrix Agardh 1824

• hormogonia give rise to young filaments with terminal heterocyst at only one end of the cellular chain
• mature trichome tapers from base, which bears a terminal heterocyst, to apex
• vegetative cells disc-shaped, isodiametric or cylindrical

SECTION V (Filamentous)

Filamentous heterocystous cyanobacteria that divide in more than one plane

reproduction by random trichome breakage, by formation of hormogonia and (if produced) by germination of akinetes

• hormogonia composed of small cylindrical cells which enlarge and become spherical
• heterocysts develop in terminal and intercalary positions
• cells in mature trichome divide in more that one plane
• associated detachment of groups of cells leads to irregular Gloeocapsa-like aggregates containing terminal heterocysts
• hormogonia are produced within such aggregates

Fischerella Gomont 1895

• hormogonia composed of small cylindrical cells which enlarge and become rounded
• heterocysts develop almost exclusively in an intercalary position
• cells in mature trichome divide in more that one plane to produce a partly multiseriate trichome with lateral uniseriate branches
• heterocysts in the primary trichome are predominantly terminal or lateral
• hormogonia are produced from the ends of trichomes or from lateral branches

References