[2] It is known with certainty from western Ecuador,[1] whereas the status of Peruvian records is ambiguous as they may refer to an undescribed species or possibly Engystomops puyango.

[3][4] Nevertheless, given that E. pustulatus is now known from Huaquillas in southern Ecuador, near the Peruvian border, it is likely to be found in Peru too.

The dorsum is strongly tubercular, with enlarged and somewhat elongated tubercles forming a "ʌ" pattern in the scapular region.

It is an explosive breeder that lays the eggs in foam nests in temporary pools.

[1] Juveniles feed primarily on small food items such as termites and ants.