Belongs within: Plagiorchiida.
The Lepocreadioidea are a group of flukes with a spiny tegument that are parasitic on fishes.
<==Lepocreadioidea
|--+--Gorgocephalus [Gorgocephalidae]OC03
| | `--G. kyphosiOC03
| `--+--EnenteridaeOC03
| | |--Enenterum aureumOC03
| | |--Koseiria xishaenseOC03
| | `--ProenenterumBC02
| | |--P. ericotylum Manter 1954BC02
| | `--P. isocotylum Manter 1954BC02
| `--GyliauchenidaeOC03
| |--Gyliauchen Nicoll 1915D56
| `--Paragyliauchen Yamaguti 1934OC03, D56
| `--P. arusettaeOC03
`--Lepocreadiidae [Lepocreadiinae]OC03
| i. s.: ‘Distomum’ sophiaeO05
|--Lepidauchen Nicoll 1913D56
| `--L. stenostoma Nicoll 1913D56
|--Lepocreadium Stossich 1903O05
| |--*L. album (Stossich 1890)O05, D56 [=Distomum albumO05]
| `--L. pegorchis Stossich 1900 (n. d.)O05
|--PreptetosOC03
| |--P. caballeroiOC03
| `--P. trullaOC03
|--Opechona Looss 1907 [incl. Pharyngora Lebour 1908]D56
| |--*O. bacillaris (Molin 1859) (see below for synonymy)D56
| |--O. orientalis (Layman 1930)D56
| `--O. retractilis (Lebour 1908) [=*Pharyngora retractilis]D56
`--Lepidapedon Stafford 1904 [=Lepodora Odhner 1905]D56
|--*L. rachion (Cobbold 1858)D56 (see below for synonymy)
|--L. elongatum (Lebour 1908) [=Lepodora elongata]D56
`--L. merrettiK-M02
*Lepidapedon rachion (Cobbold 1858)D56 [=Distoma rachionO05, Distomum rachionD56, *Lepodora rachiaeaO05; incl. Lepodora rachiaea gymnacanthi Issaitschikow 1928D56, Distoma increscens Olsson 1868D56]
*Opechona bacillaris (Molin 1859) [=Distoma bacillare, Distoma (Dicrocoelium) bacillare, Distomum bacillare, Pharyngora bacillaris]D56
*Type species of generic name indicated
References
[BC02] Bray, R. A., & T. H. Cribb. 2002. Observations on the phylogeny of Opisthadena Linton, 1910 and related genera (Hemiuridae: Opisthadeninae) from Australian and French Polynesian waters. Folia Parasitologica 49: 279–290.
[D56] Dawes, B. 1956. The Trematoda with special reference to British and other European forms 2nd ed. University Press: Cambridge.
[K-M02] Klein-MacPhee, G. 2002. Cods. Family Gadidae. In: Collette, B. B., & G. Klein-MacPhee (eds) Bigelow and Schroeder’s Fishes of the Gulf of Maine 3rd ed. pp. 223–261. Smithsonian Institute Press: Washington.
[O05] Odhner, T. 1905. Die Trematoden des arktischen Gebietes. In: Römer, F., & F. Schaudinn (eds) Fauna Arctica. Eine Zusammenstellun der arktischen Tierformen, mit besonder Berücksichtigung des Spitzbergen-Gebietes auf Grund der Ergebnisse der Deutschen Expedition in das Nördliche Eismeer im Jahre 1898 vol. 4 pp. 289–372. Gustav Fischer: Jena.
[OC03] Olson, P. D., T. H. Cribb, V. V. Tkach, R. A. Bray & D. T. J. Littlewood. 2003. Phylogeny and classification of the Digenea (Platyhelminthes: Trematoda). International Journal for Parasitology 33: 733–755.