Ascocotyle is a genus of intestinal trematodes within the family Heterophyidae, established by Arthur Looss in 1899. These parasites are classified under the phylum Platyhelminthes, class Trematoda, and order Plagiorchiida. The genus is widely distributed, with records spanning latitudes from -43 to 47 and longitudes from -118 to 48, and it comprises approximately 45 descendant taxa.[1][2][3][4]
Species within this genus, such as Ascocotyle (Phagicola) longa, are recognized as causative agents of fish-borne trematodosis, posing a public health concern in regions where raw fish consumption is common. The life cycle of A. (P.) longa typically involves the cochliopid snail Heleobia australis as the first intermediate host. Metacercariae encyst in various tissues of the second intermediate host, such as the mullet Mugil liza, particularly in estuarine and coastal lagoon environments. The adult parasites exhibit a broad host range, infecting various fish, mammals, and birds.[5][1]
Morphological studies of A. (P.) longa reveal distinct developmental changes in tegumental spination. Cercariae possess single-pointed spines, whereas metacercariae and adult stages exhibit multipointed, brush-shaped spines. Both rediae and cercariae have been documented for this species.[5]