OPISTHORCHIIDAE LOOSS, 1899

Sokolov, Sergey, Frolov, Evgeniy, Novokreshchennykh, Semen & Atopkin, Dmitry, 2021, An opisthorchiid concept of the genus Liliatrema (Trematoda: Plagiorchiida: Opisthorchioidea): an unexpected systematic position, Zoological Journal of the Linnean Society 192 (1), pp. 24-24 : 24-

FAMILY OPISTHORCHIIDAE LOOSS, 1899

Synonyms: Ratziidae Posche, 1926 (see Scholz, 2008); new synonyms Liliatrematidae Gubanov, 1953 and Heterophyidae Leiper, 1909 pro parte.

Diagnosis [modified from family diagnosis of Scholz (2008) and our data]: Body small- to mediumsized, variable in shape, unarmed or spined. Oral sucker terminal or subterminal, unspecialized or funnel-shaped, with penta- or heptagonal distal end, sometimes reduced or rudimentary. Ventral sucker usually pre-equatorial, well developed, exceptionally reduced or rudimentary. Pharynx present. Oesophagus short or long. Intestine bifurcating in forebody. Caeca long, reaching testicular level or posterior extremity, straight or sinuous, blind, exceptionally opening via two ani or forming uroproct. Testes two or one, variable in shape, tandem, oblique or opposite, in posterior half of body. Cirrus-sac absent. Seminal vesicle usually tubular, undivided or bipartite, in forebody, rarely equatorial or in hindbody. Genital or ventrogenital sac absent, occasionally present; if present, median: genital sac without gonotyl, and ventrogenital sac containing one or two unarmed preacetabular gonotyls and well-developed ventral sucker or without gonotyl but with rudimentary ventral sucker. Genital pore median or slightly submedian, mostly to ventral sucker. Ovary entire or lobed, median or submedian, mostly pretesticular. Seminal receptacle canalicular, rarely uterine. Uterus pretesticular, rarely posterior to testes. Vitellarium follicular, in two lateral fields. Excretory vesicle Y- or T-shaped. Adults in liver, biliary system, pancreas or intestine of terrestrial and aquatic vertebrates, cosmopolitan. Type genus Opisthorchis Blanchard, 1895 .

SUBFAMILY APOPHALLINAE CIUREA, 1924

Diagnosis [modified from subfamily diagnosis of Yamaguti,(1971) and generic diagnosis of Pearson (2008)]: Body pyriform to elliptical or more elongate, spined. Oral sucker unspecialized. Ventral sucker well developed, with axis inclined anteriorly. Pharynx present. Caeca terminating at or near posterior extremity. Testes two or one, entire, tandem or oblique. Cirrus-sac absent. Seminal vesicle elongate, S-shaped, undivided but sometimes constricted; pars prostatica present. Ventrogenital sac permanent, median. Gonotyls two, lateral and opposite, arising dorsally close against ventral sucker, clavate in lateral aspect, rounded in ventral aspect, overhanging ventral sucker ventrally. Genital pore anteromedian to ventral sucker. Ovary entire, submedian, pretesticular. Seminal receptacle canalicular. Uterus pretesticular. Vitellarium follicular; follicles in two lateral fields extending from posterior extremity to level of ventral sucker or beyond to intestinal bifurcation. Excretory vesicle Y- or T-shaped; stem long, sigmoid, passing between two testes. Intestinal parasites of birds and mammals; Eurasia and North America. Type and only genus Apophallus Lühe, 1909 .

SUBFAMILY CRYPTOCOTYLINAE LÜHE, 1909