They are endemic to Mexico and found in southern Veracruz and Puebla to Guerrero and Oaxaca.

In such cases, species have diverged in terms of body size and dentition, apparently facilitating niche differentiation.

Their extreme miniaturization is accompanied by determinate growth and skeletal reduction.

Their skeleton also shows unique features, such as ossifications of many elements that remain cartilaginous in other salamanders.

In contrast, they tend to be similar in appearance, making it difficult to distinguish species.