[a] The genus Mayarhynchus Pinacho-Pinacho, Hernández-Orts, Sereno-Uribe, Pérez-Ponce de León & García-Varela, 2017 is different from the other 17 genera in Neoechinorhynchidae by having a small proboscis.

[3] It contains only one species: Mayarhynchus karlae Pinacho-Pinacho, Hernández-Orts, Sereno-Uribe, Pérez-Ponce de León & García-Varela, 2017.

[3] Atactorhynchus Chandler, 1935 has two species: A. duranguensis has been found in the intestine of the Mezquital pupfish (Cyprinodon meeki) a fish from in-land Mexico.

Diagnostic features include: body small, stout, ventrally curved; small cylindrical proboscis armed with 16 alternating vertical rows of four or five hooks; anterior two or three hooks conspicuous, stout and larger than other hooks, and have large, rod-shaped roots with a markedly and abruptly enlarged base; three posterior hooks of each row are smaller and rootless; single-walled proboscis receptacle; lemnisci equal in length, elongate and robust; and cement gland syncytial, larger than testis.

Unlike A. verecundus, the base of the roots are markedly and abruptly enlarged in the new species.