Description: "Body bipartite; forebody infundibular, cup-shaped or spherical; hindbody fusiform, reniform or subcylindrical, more or less arched, with neck region absent. Oral and ventral suckers well developed; ventral larger than oral; pharynx present. Testes tandem in posterior half of body. Ovary reniform or ovoid. Vitellarium in hindbody, confined to ventral and subventral fields. "Seminal vesicle situated dorsally to hind testis. Uterus extends anterior to ovary. Copulatory bursa terminal, rather small; muscular ring absent; genital cone not or poorly delimited from surrounding parenchyma. Hermaphrodiic duct, formed by union of distal part of uterus and ejaculatory duct, opens close to apex or cone. Mostly in piscivorous birds. Holarctic region, Brazil, Congo. Metacercariae or 'tetracotyle' type in fishes. Cercariae with two groups of four small postacetabular penetration glands and flame-cell formula 2[(1+1)+(1+1+1)]=10; excretory commissure posterior to ventral sucker; alimentary system rudimentary. Type species A. gracilis (Rudolphi, 1819) Szidat, 1928" (Bray et al., 2002).
Life Cycle: “Metacercariae of ‘tetracotyle’ type, in invertebrates (leeches, gastropods), fishes, amphibians and birds. Mesocercariae may be present in life cycle (in amphibians. Adult in birds, accidentally in reptiles” (Bray et al., 2002).
Sources: Bray, R.A., Gibson D.I., and Jones, A. 2002. Keys to the Trematoda, Vol. 1, p. 231-241.