Asterocaelum anabaenophilum Cook & Ahearn, 1976


Diagnosis: Trophozoites 32-75 µm, sometimes up to 300 µm. Pseudopodia without any light microscopically visible inner axis. One or more nuclei. Digestion cysts spherical (15-75 µm) with spines and mucous envelop. 1-4 amoebae leaf the cyst, often some minutes after cystbuilding. Remaining protoplasm in the cyst often builds eccentrically in the old cyst wall a thick walled apparent resting cyst. No excystation observed.    


Ecology: Feeding on Anabaena planctonica. Freshwater, North-America.


Remarks: Amoebae have been observed to bloom in water kept in the laboratory (Bovee, 1970), but blooms of algophorous amoebae extensive enough to decimate massive blooms of Anabaena sp. in lakes have not been reported previously. The voracious feeding and apparent food specificity of this large free-living amoeba suggest that it may serve as a natural control system for blooms of Anabaena spp. Laboratory culture of the amoeba with determination of its response to environmental conditions eventually may permit its practical use for the treatment of certain nuisance algal blooms (Cook and Ahearn, 1976).


Asterocaelum sp.
Asterocaelum anabaeophilum, from Cook et al., 1973