There are over 60 species classified into three genera in Gigantorhynchida Gigantorhynchus, Intraproboscis, and Mediorhynchus.

[2][7] The body, or trunk, is long with pseudosegmentation, the lemnisci are filiform, and the testes are ellipsoid.

[2] Males of all species possess eight cement glands which are used to temporarily close the posterior end of the female after copulation.

[2] Gigantorhynchus species infest marsupials and myrmecophagids (anteaters) in Central and South America.

[2] The genus Intraproboscis Amin, Heckmann, Sist, and Basso, 2021[9] contains one species, I. sanghae .