Coelosphaerium sp.

Key to families

- Cells solitary or forming irregular, flat or spherical mucilaginous colonies, cell division in two planes in successive generations ... Merismopediaceae (Genera included in this volume: Aphanocapsa, Coelosphaerium, Gomphosphaeria, Merismopedia, Pannus, Snowella, Synechocystis, Woronichinia)

Key to genera
1. Cells arranged at periphery of spherical colonies (sometimes slightly displaced) at the ends of a structured mucilaginous stalk system radiating from the centre of the colony .............................................................................2
- Cells arranged at the periphery of spherical colonies without a structured central mucilaginous stalk system, sometimes with unstructured gelatinous mucilage at the centre of colonies .......................................Coelosphaerium
2. Cells attached to the ends of thin, pseudodichotomously branched divicariate stalks which radiate from the centre of the colony ........................................................................................................................................................Snowella
- Cells at the ends of or within wide mucilaginous stalks which are up to as wide as the cells (sometimes only visible with phase contrast or after staining) ...........................................................................................................................3
3. Stalk system composed of indistinct, fine, gelatinous, paralell tubes radiating from the colony centre, each stalk with radially arranged spherical or oval cells, cells densely arranged at the colony periphery ........................Woronichinia
- Stalk system thick, divided and diffuse, widened at the ends and enveloping the peripherially arranged cells; cells obovoid, remaining connected after division to form cordiform pairs.............................................. Gomphosphaeria