Dolichospermum sp. Straight
KEY TO FAMILIES
1. Filamentous, heterocystous, isopolar, with free uniseriate trichomes enveloped by fine mucilaginous envelopes or sheaths.
Filaments ± straight, flexuous, or ± irregularly screw-like coiled, without branching; all vegetative cells capable of cell division.
Vegetative cells spherical, barrel-shaped to cylindrical, apical cells rounded, conical, acutely pointed or cylindrical and bluntly
rounded, with or without aerotopes. Heterocytes terminal or intercalary. Akinetes often several times larger than vegetative cells,
formed from one vegetative cell or from the fusion of several vegetative cells, positioned adjacent or remote from heterocytes
..............................................................................................................................................................1. APHANIZOMENONACEAE
(Genera included in this volume: Anabaenopsis, Aphanizomenon, Chrysosporum, Cuspidothrix, Dolichospermum, Nodularia,
Raphidiopsis, Sphaerospermopsis)
KEY TO GENERA
1. Trichomes always without heterocytes.......................................................................................................................RAPHIDIOPSIS
- Trichomes capable of producing heterocytes......................................................................................................................................2
2. Heterocytes terminal.............................................................................................RAPHIDIOPSIS (in part, ex. Cylindrospermopsis)
- Heterocytes intercalary........................................................................................................................................................................3
3. Heterocytes develop in pairs which, following trichome breakage, are in the terminal position.......................... ANABAENOPSIS
- Heterocytes solitary.............................................................................................................................................................................4
4. Apical cells generally differentiated, elongated, tapered, or hyaline..................................................................................................5
- Apical cells generally undifferentiated................................................................................................................................................6
5. Apical cells elongated, attenuated and acuminate................................................................................................... CUSPIDOTHRIX
- Apical cells conical, or tapered and elongated, often hyaline..............................................................................CHRYSOSPORUM
6. Vegetative cells always distinctly shorter than broad....................................................................................................NODULARIA
- Vegetative cells ± isodiametric or longer than wide............................................................................................................................7
7. Akinetes spherical, always developing either side of the heterocytes........................................................ SPHAEROSPERMOPSIS
- Akinetes adjacent to or remote from heterocytes................................................................................................................................8
8. Akinetes long cylindrical, often with a collar-like extension at either end which extends over the adjacent vegetative cells.............
.............................................................................................................................................APHANIZOMENON (in part A. gracile)
- Akinetes oval to cylindrical.............................................................................................................................DOLICHOSPERMUM
KEY TO SPECIES
1. Filaments straight or slightly flexuous................................................................................................................................................2
- Filaments regularly or irregularly coiled.............................................................................................................................................4
2. Filaments < 6 μm broad..........................................................................................................................................................D. affine
- Filaments > 6 μm broad......................................................................................................................................................................3
3. Akinetes spherical to broadly ovate......................................................................................................................................D. smithii
- Akinetes oblong-ovate or oblong with conical ends................................................................................................ . D. planktonicum
4. Filaments regularly screw-like coiled.................................................................................................................................................5
- Filaments irregularly coiled.................................................................................................................................................................7
5. Akinetes oval to cylindrical.................................................................................................................................................................6
- Akinetes cylindrical reniform.......................................................................................................................................D. perturbatum
6. Vegetative cells globose, 8.0–12.0 μm in diameter............................................................................................................ D. crassum
- Vegetative cells spherical, (4.0–) 7.0–9.0 μm long × 6.0–8.5 μm broad.......................................................................... D. spiroides
7. Vegetative cells > 5 μm in diameter...................................................................................................................................D. circinale
- Vegetative cells < 5 μm in diameter....................................................................................................................................................8
8. Akinetes cylindrical, slightly arcuate, solitary or up to two in series, adjacent to or remote from the heterocytes..... D. helicoideum
- Akinetes cylindrical reniform, solitary or in pairs, remote from the heterocytes............................................................. D. flosaquae
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