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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-

Site of infection: Musculature.

Specimens deposited: Three voucher specimens, IPEE RAS 14287, 14288.

Description (based on three whole-mounted excysted specimens, two SEM-studied specimens, two slides with the isolated terminal genitalia and one slide with the sagittal section of the body): Body elongate; length 4497– 5013, maximum width 976–1061 in posterior half of body. Tegument spinose; spines multipointed, becoming sparser toward posterior end of body. Eye-spots at the level of the prepharynx. Oral sucker terminal, funnelshaped, 650–707 × 763–820, with heptagonal distal (outer) end. Dorsal edge of distal end of oral sucker covered with hood-like fold of tegument. Ventral sucker well developed, rounded, 329–357 × 294–315, recessed within tegumental crypt. Forebody 45.6–50.9% of body length. Prepharynx 196–350. Pharynx elongateoval 378–385 × 49–112. Oesophagus 280. Intestine bifurcating distinctly anteriorly to ventral sucker. Caeca reaching to posterior end of body, connecting to excretory vesicle, forming uroproct.

Testes two, transversely elongated, indented, nearly tandem, in posterior half of body; anterior testis 140– 224 × 455–462, posterior testis 182–245 × 385–434. Post-testicular region 19.5–20.8% of body length. Cirrus-sac absent. Seminal vesicle, pars prostatica with field of prostatic cells, and ejaculatory duct lying free in parenchyma. Seminal vesicle bipartite, with relatively short proximal portion and long distal portion, running dextrally to ventral sucker. Pars prostatica vesicular, surrounded by field of prostatic cells. Ejaculatory duct short, connecting with genital atrium. Genital atrium short, opening dextro-submedially at base of genital sac. Genital sac with lip-like posterior wall overlapping anterior part of recessed ventral sucker; median, surrounded by smaller gland cells.

Ovary tetralobed, pretesticular and dextrosubmedial, 105–126 × 189–196. Seminal receptacle canalicular, saccular, mainly posterior to ovary. Laurer’s canal opening dorsomedially just posterior to ovary level. Oötype not observed. Mehlis’ gland extensive. Uterus pretesticular, running sinistrally to ventral sucker, curved anteriorly to sucker and opening in genital atrium. Vitellarium follicular; anlage of follicles in two longitudinal lateral fields extending from level of ovary to posterior extremity of body, overlapping caeca ventrally and dorsally, and almost confluent in post-testicular region. Excretory vesicle Y-shaped, extending to ovary level.