Group name:
Cyanobacteria
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Key to Cyanobacteria
Cyanobacteria (Blue-green algae) |
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|---|---|
| 1a. Unicells or colonies | Group 1: Unicells and colonies (2 to 17) |
| 1b. Filamentous | Group 2: Filamentous (18 to 39) |
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| 2a. Cells differentiated (heteropolar), with distinct basal and apical ends, attached by basal end to the substratum, solitary or aggregated in groups | 3 |
| 2b. Cells undifferentiated (isopolar), solitary or in colonies | 8 |
| 3a. Cells ditributed at the ends of mucilaginous, crosswise lamellated, colorless, radially oriented and irregularly curved stalks | Cyanostylon |
| 3b. Cell not distributed at the ends of stalks | 4 |
| 4a. Cell reproduce by exospores separated individually or remain in rows at the apex of the mother cell | 5 |
| 4b. Cell reproduce by endospores (baeocytes) formed from successive division of the whole mother cell and disperse from ruptured sheath | 6 |
| 5a. Thin sheath of the cell narrowed at apex into conspicuous short or long hair-like projection | Clastidium |
| 5b. Sheath of the cell without apical hair-like projection | Chamaesiphon |
| 6a. Cells in pseudofilaments creeping along substrata | Pleurocapsa |
| 6b. Cells in colonies attached to substrata | 7 |
| 7a. Cells similar in size, form a monolayer on substrata | Xenococcus |
| 7b. Cells different in size, sometimes form short irregular rows | Chroococcopsis |
| 8a. Cells oval to cylindrical, divide exclusively perpendicular to one (usually longer) cell axis | 9 |
| 8b. Cells variable in shape (spherical, hemispherical, ovoid, irregularly elongated), divide in two or more planes | 12 |
| 9a. Cells in mucilaginous colonies | Aphanothece |
| 9b. Unicells or in pairs or irregular groups after division, do not form distinct colonies | |
| 10a. Cells with reticulate content | Cyanothece |
| 10b. Cell content more or less homogenous | 11 |
| 11a. Cells very small, cell diameter < 1 µm, epiphytic | Cyanobium |
| 11b. Cells larger, cell diameter > 1.5 µm, not epiphytic | Synechococcus |
| 12a. Cells divide in two directions in successive generations; colonies flat or nearly spherical | 13 |
| 12b. Cells divide in three or more directions in successive generations; colonies of various shape | 15 |
| 13a. Colonies square or rectangular, with one layer of cells arranged in perpendicular rows | Merismopedia |
| 13b. Colonies more or less spherical, cells not arranged in perpendicular rows | 14 |
| 14a. Cells spherical, irregularly arranged in homogenous colorless colonial mucilage | Aphanocapsa |
| 14b. Cells slightly club-shaped or cordiform (heart-shaped), radially oriented at the colony periphery; colony with central system of thick mucilaginous stalks | Gomphospheria |
| 15a. Cells spherical, irregularly (sometimes densely) scattered in various shaped colonies | |
| 15b. Cells hemispherical or elongate, only at first spherical, arranged in three-dimensional spheroid clusters | 17 |
| 16a. Cells with gas vesicles, individual sheaths indistinct | Microcystis |
| 16b. Cells without gas vesicles, individual sheaths wide, distinct | Gloeocapsa |
| 17a. Mucilaginous sheaths copying the cell form, sometimes lamellated, distinct or diffuse at the margins, cells regularly arranged | Chroococcus |
| 17b. Mucilaginous sheaths fine, homogenous, and diffuse, cells irregularly arranged | Limnococcus |
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| 18a. Filaments undifferentiated, heterocysts and akinetes never occur | 19 |
| 18b. Filaments differentiated, heterocysts and akinetes develop commonly or occasionally | 30 |
| 19a. Trichomes cylindrical to moniliform, not narrowed toward the end | 20 |
| 19b. Trichomes narrowed toward the end, terminal hairs may be present | Homoeothrix |
| 20a. Trichomes without individual sheaths | 21 |
| 20b. Trichomes with individual sheaths, one or more trichomes in sheath | 25 |
| 21a. Trichomes straight or wavy | 22 |
| 21b. Trichomes irregularly or screw-like coiled | 24 |
| 22a. Trichomes cylindrical, not monoliform | 23 |
| 22b. Trichomes distinctly moniliform, cells deeply constricted at cross walls | Komvophoron |
| 23a. Trichomes solitary, cells with finely but distinctly reticulate content | Tychonema |
| 23b. Trichomes usually in mats, cells with more or less homogenous content, not reticulate | Oscillatoria |
| 24a. Coils free, long and wide, trichomes solitary | Glaucospira |
| 24b. Coils joined one to another, trichomes in mats | Spirulina |
| 25a. One trichome per sheath | 26 |
| 25b. Sheath wide, containing two or more trichomes | 29 |
| 26a. Trichomes < 3 µm wide | 27 |
| 26b. Trichomes > 3 µm wide | 28 |
| 27a. Filaments heteropolar, individually attached by one end to substratum | Heteroleibleinia |
| 27b. Filaments isopolar, loosely arranged in flake-like clusters or mats | Leptolyngbya |
| 28a. Sheath always occur, usually thick, lamellated, colorless or yellow-brown | Lyngbya |
| 28b. Sheath usually occur, but sometimes absent, thick or thin, not lamellated or colored | Phormidium |
| 29a. Trichomes < 3 µm wide, filaments rich pseudobranched with a few trichomes, sheath often lamellated | Schizothrix |
| 29b. Trichomes > 3 µm wide, filaments unbranched with many trichomes, sheath homogenous, not lamellated | Microcoleus |
| 30a. Trichomes not branched or only with false branching | 31 |
| 30b. Trichomes with true branching | Nostochopsis |
| 31a. Trichomes not branched | 32 |
| 31b. Trichomes with lateral false branching | 36 |
| 32a. Heterocysts terminal with single pore | Cylindrospermum |
| 32b. Heterocysts intercalary (terminal are axceptional) with pores on either side | 33 |
| 33a. Akinetes solitary or up to five in row, adjacent to heterocyst or distant, mature akinetes several times larger than vegetative cells | Anabaena |
| 33b. Akinetes many in long row, positioned between heterocysts, mature akinetes slightly larger than vegetative cells | 34 |
| 34a. Trichomes united into firm colonies (often macroscopic) with a distinct, defined margin | Nostoc |
| 34b. Trichomes solitary or in amorphous mats | 35 |
| 35a. Cells and akinetes always shorter than wide | Nodularia |
| 35b. Cells and akinetes always longer than wide | Trichormus |
| 36a. Trichomes isopolar, cylindrical up to the end, with double false branching between two heterocysts | Scytonema |
| 36b. Trichomes heteropolar | 37 |
| 37a. Trichomes cylindrical, heteropolar growth indistinct, heterocysts mostly intercalary (and basal), single false branching at heterocyst, rarely in older filament double false branching | Tolypothrix |
| 37b. Trichomes distinctly attenuated toward end, terminal multicellular hairs may be present, heterocysts mostly basal (rarely intercalary before branching), single false branching at heterocyst | 38 |
| 38a. Filaments distinctly false branched, in fascicles or mucilaginous colonies | 39 |
| 38b. Filaments rarely false branched, occur singly or in groups, but always distinctly separated one from another | Calothrix |
| 39a. Filaments with firm individual sheaths, unified more or less in parallel forming flat or spherical (hemispherical) colonies | Rivularia |
| 39b. Filaments with firm or gelatinous lamellated individual sheaths, unified in fascicles | Dichothrix |
