Sphaerospermopsis sp.
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
Filaments planktonic; trichomes solitary, coiled or straight, constricted at the cross walls, with or without mucilaginous
sheaths. Apical cells elongated and tapered in straight species, or undifferentiated in coiled species. Vegetative cells
spherical or barrel-shaped, compressed during division, with aerotopes. Heterocytes intercalary, solitary, spherical.
Akinetes spherical or widely oval, adjacent to either side of the heterocytes.
A widely distributed genus of seven species known from freshwater lakes and reservoirs, rivers and estuaries.
Here three species are described from north-eastern Australia. Bibliography: ZapomÄ›lová et al. (2009, 2010), Werner
et al. (2012), Li et al. (2015, 2016).
1. Trichomes straight...............................................................................................................................................S. aphanizomenoides
- Trichomes coiled.................................................................................................................................................................................2
2. Coils (7.0–) 8.5–15.8 μm in diameter............................................................................................................................ S. eucompacta
- Coil diameter 12–
24 μm in diameter................................................................................................................................ S. reniformis
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