At first glance you’d think that’s an ant rather than a true bug. Look closely though and the beak gives it away. These broad-headed bug nymphs (Family Alydidae) were easily found on the same foliage where I saw some Ectatomma ants. Perhaps those ants are the model for this mimic. The caption for this photo certainly suggests that’s the case.
Here’s a side by side comparison.
Notice how the antenna tips are darker in the photo below. I wonder if that makes them appear shorter and closer in length to the model?
In the lead photo and in the one below, you can see wings developing.
Here’s one last photo.