Belongs within: Trematoda.
The Cyathocotylidae are flukes parasitic in the intestines of amniotes (Dawes 1956).
Characters (Dawes 1956): Distomes of rounded outline with body is not divided into anterior and posterior regions. Cirrus pouch very large, cirrus large, pars prostatica and seminal vesicle present. Gonads rounded, prominent, ovary between testes. Vitellaria very well developed, laterally along whole extent of body. Adhesive organ very large, occupying middle of body behind ventral sucker. Glands absent. Excretory system with flame-cell formula 2 [(2) + (2) + (2) + (2) + (2)]. Hosts reptiles, birds and mammals. Location intestine.
<==Cyathocotylidae
| i. s.: Prohemistomum vivax (Sonsino 1892) [=Cercaria vivax; incl. P. spinulosum Odhner 1913]D56
|--Mesostephanus Lutz 1935 [Prohemistomatinae]D56
| `--M. appendiculatum (Ciurea 1916) [=Prohemistomum appendiculatum]D56
|--PharyngostomatinaeD56
| |--Pharyngostomum Ciurea 1922 [Pharyngostomatinae]D56
| | `--P. cordatum (Diesing 1850) (see below for synonymy)D56
| `--Pharyngostomoides Harkema 1942D56
| `--*P. procyonis Harkema 1942D56
`--CyathocotylinaeD56
|--Duboisia Szidat 1936D56
| `--*D. syriaca (Dubois 1934) [=Prohemistomum syriacum]D56
|--Holostephanus Szidat 1936D56
| `--*H. luhei Szidat 1936D56
|--Cyathocotyloides Szidat 1936D56
| |--C. curonensis Szidat 1936D56
| `--C. dubius Szidat 1936D56
`--Cyathocotyle Mühling 1896D56
|--C. fraterna Odhner 1902D56
|--C. oviformis Szidat 1936D56
`--C. prussica Mühling 1896D56
Pharyngostomum cordatum (Diesing 1850) [=Hemistomum cordatum, Alaria cordata, He. kordatum; incl. Holostomum linguaeformis Dubois 1938, Diplostomulum mutadomum Wallace 1937, Diplostomum putorii Linstow 1877]D56
*Type species of generic name indicated
References
[D56] Dawes, B. 1956. The Trematoda with special reference to British and other European forms 2nd ed. University Press: Cambridge.