Thorius narismagnus is a species of salamander in the family Plethodontidae.

It is endemic to the San Martin Tuxtla volcano, in the Sierra de los Tuxtlas range in southern Veracruz state, Mexico.

[1][2] Natural habitats of Thorius narismagnus are lowland and intermediate tropical forests.

It occurs under rotten logs and among leaf-litter, and especially under fallen bromeliads.

It has suffered from habitat loss, but this might not suffice to explain the disappearance of this species.