534 Host-Parasite Relationships 



symbiotic. Various other cases of parasitism may result in destruction of 

 the protozoan host. 



Protozoan parasites of Protozoa 



Some of the most interesting of these parasites are Suctorea which, 

 at one time, were believed to be embryonic stages of ciliates. Species of 

 Endosphaera (31, 66) differ from free-living Suctorea in the absence of 

 tentacles throughout the life-cycle. There are also a few parasitic species 

 of Sphaerophrya which have tentacles in the free-living stage but discard 

 them upon invading a protozoan host. In addition to Suctorea, various 

 other parasites of Protozoa are known. Dinoflagellates have been reported 

 from dinoflagellate (17), ciliate (39), and radiolarian hosts. A species of 

 Astasia has been observed in Stentor and Spirostojmim (41) and unidenti- 

 fied Zoomastigophorea have been found in ciliates, Suctorea, and Myxo- 

 sporida. Small amoebae have been reported from opalinid ciliates (88) 

 and from Trichodina; Microsporida, from Myxosporida (60), ciliates, 

 gregarines, and Hypermastigida; several Haplosporidia, from gregarine 

 hosts (68). Some of these associations are examples of hyperparasitism (86). 



Bacterial parasites of Protozoa 



Certain bacteria are ectoparasitic on flagellates of termites (25, 

 32, 48, 52, 54). Fusiform bacilli, adherent lengthwise to the cortex of the 

 host and often regularly spaced, have sometimes been mistaken for 

 cortical ridges in Devescovina, Lophomonas, Polymastix, Caduceia, and 

 Staurojoenia. Similarly attached bacteria also have been reported from 

 ciliates, including a species of Cyclidium (80). Spirochetes, attached 

 terminally to their hosts (21, 25, 48), have been mistaken occasionally for 

 flagella or cilia. Although less common than spirochetes, terminally at- 

 tached bacilli have been observed on such flagellates as Microrhopalodina 

 (Proboscidiella) kofoidi (50) and M. inflata (26). 



Endoparasitic bacteria also occur in certain flagellates of termites — 

 Trichonyrnpha (51), Pseudodevescovina (54, 33), and Bullanympha (55). 

 Both nuclear and cytoplasmic parasites have been reported from Para- 

 mecium (11, 27), for which invasion of the macronucleus is often fatal. 



Other plants as parasites of Protozoa 



This group includes such Fungi as Chytridiales which sometimes 

 occur as cytoplasmic (Sphaerita) and nuclear parasites (Niicleophaga) 

 in Protozoa. Species of Sphaerita have been described from Euglenida 

 (30, 46, 73), Amoeba (71), flagellates of termites, species of Entamoeba, 

 Zelleriella, Nyctotherus, and Diplodiniwn (57). The young form of 

 Sphaerita is a uninucleate amoeboid stage. Growth and nuclear division 

 result in a plasmodium, which eventually produces a number of small 

 spores, or sometimes flagellated "zoospores." Niicleophaga (61) has been 



