In this holotrichasin, suctoriorid family the tentacles are capitate and are usually arranged in groups. Endogenous budding occurs. A lorica is often present, and a stalk is present or absent.
The body is elongate, with 1 or more tentacles at each end, but without lorica or stalk. The macronucleus is ovoid or spherical, and the micronucleus is compact. There is 1 contractile vacuole. The cytoplasm is often filled with small spheroidal bodies.
Allantosoma intestinalis Gassovsky, 1919 has a sausage-shaped body with 3 to 12 tentacles at each end bearing distinct suckers. It measures 33 to 60 by 18 to 37 u. The cytoplasm is filled with small, round bodies. The macronucleus is more or less spherical. Hsiung (1930) found this species in the cecum of 6 and the colon of 8 out of 46 horses in Iowa.
A. dicorniger Hsiung, 1928 has a more or less cycloid body with 1 incurved tentacle at each end, and measures 20 to 33 by 10 to 20 u. The end of the tentacle is somewhat boot-shaped. The cytoplasm is filled with granules. The macronucleus is subspherical. Hsiung (1930) found this species in the colon of 2 out of 46 horses in Iowa.
A. brevicorniger Hsiung, 1928 has an elongate, cycloid body with 1 short, slender slightly incurved tentacle at each end. It measures 23 to 36 by 7 to 11 u. The distal end of the tentacle is rounded. The cytoplasm is slightly granular. Hsiung (1930) found this species in the cecum of 9 out of 46 horses in Iowa.