Nyctotherus ovalis Leidy
Synonymy.—Bursaria blattarum; Plagiotoma blattarum.
Natural hosts.—Blatta orientalis, U.S.A. (Leidy, 1850, 1853, 1853b, 1879a; Kudo, 1922, 1926, 1936; McAdow, 1931; Kudo and Meglitsch, 1938; Meglitsch, 1940); Germany (Stein, 1860; Schubotz, 1905; Chen, 1933); England (Lankester, 1865; Schuster, 1898; Lucas, 1927a, 1928); Spain (Zulueta, 1916); U.S.S.R. (Yakimov and Miller, 1922; Zasukhin, 1928, 1930; Ostroumov, 1929); Portugal (Lima Ribiero, 1924); Brazil (Pinto, 1926); Venezuela (Tejera, 1926).
Blattella germanica, South Africa (Porter, 1930); U.S.A. (Balch, 1932; McAdow, 1931).
Parcoblatta pensylvanica, U.S.A. (Semans, 1939, 1941).
Periplaneta americana, India (Bhatia and Gulati, 1927); Indochina (Weill, 1929); Philippine Islands (Hegner and Chu, 1930); South Africa (Porter, 1930); U.S.A. (McAdow, 1931; Hatcher, 1939; Meglitsch, 1940; Armer, 1944); Goa (Mello et al., 1934); China (Pai and Wang, 1947); Czechoslovakia (Low, 1956).
"Barata sylvestre," Brazil (Pinto, 1926).
"Küchenschaben," Austria (Bělǎr, 1916).
Nyctotherus ovalis (fig. 2, G) inhabits the hind gut of cockroaches, where it occurs almost always in the anterior half of the colon in association with other species of Protozoa (Kudo, 1936). Ninety percent of 500 B. orientalis contained N. ovalis (Kudo and Meglitsch, 1938). Yakimov and Miller (1922) found N. ovalis in 68 percent of 124 B. orientalis. Zasukhin (1930) found this organism in 63 percent of over 3,000 B. orientalis. Zasukhin (1928, 1934) found a fungus and possibly a bacterium hyperparasitic in the cytoplasm of N. ovalis. N. ovalis has been cultured outside the cockroach in several media (Lucas, 1928; Balch, 1932; Chen, 1933; Low, 1956).