Mesocoelidae Dollfus, 1929

Dronen, Norman O., Calhoun, Dana M. & Simcik, Steven R., 2012, Mesocoelium Odhner, 1901 (Digenea: Mesocoelidae) revisited; a revision of the family and re-evaluation of species composition in the genus 3387, Zootaxa 3387 (1), pp. 1-96 : 6

Family Mesocoelidae Dollfus, 1929

Diagnosis. Relatively small, spinose flatworms, elongate to oval or elliptical, some species clavate. Oral sucker subterminal; mouth opening ventrally; prepharynx short; pharynx muscular; esophagus present; intestinal bifurcation immediately preacetabular; ceca short (not surpassing ovary posteriorly) to moderately long (surpassing ovary posteriorly, extending some distance into postovarian space). Ventral sucker above midlevel of body. Testes tandem to nearly side by side, intercecal, usually at level of ventral sucker, occasionally postacetabular. Cirrus sac well developed, enclosing seminal vesicle, may overlap anterior margin of ventral sucker. Genital pore preacetabular. Ovary postesticular. Seminal receptacle posterior to ovary. Laurer’s canal present. Uterus with highly folded descending and ascending limbs, filling most of postovarian space. Vitellaria follicular, in bands along ceca; vitelline fields reaching to level of esophagus or more anterior, posterior extent variable, terminating from some distance anterior to the ventral sucker to midlevel of postovarian space or more posterior. Excretory vesicle Y-shaped, with poorly developed arms to I-shaped; excretory pore terminal to slightly subterminal. Life cycle poorly known. Adults found worldwide in intestines of amphibians and reptiles, rarely fish.

Type genus. Mesocoelium Odhner, 1910 .