Leptodactylus menanonotus tadpoles are large, fast, benthic generalists with a streamlined body.  Their body is somewhat greenish and generally dark.  The oral disk is complete, and the mouth is beaked with 2/3 denticles.  The second denticle is sometimes broken according to Savage, but has always appeared a below in the specimen I observed.

I’m unsure how to tell the other common Leptodactylus tadpoles from this species (L. fragilis [formerly labialis] and mislabeled as L. poecilochilus here and here).

Other tadpole posts:

Rhinophrynus dorsalis
Engystomops pustulosus
Incilius luetkenii
Smilisca baudinii
Hyla microcephala
Leptodactylus melanonotus