Schagonaria is a genus of trilobite, an extinct group of marine arthropods.
The only known species, S. tannuola occurs in the earliest Middle Cambrian of Russia (Amgaian, Ulukhema River, Tuva Region).
It is related to Paradoxides, but can be distinguished from it by only slightly forward expansion of the glabella, a character shared with Anabaraceps and Primoriella.
In Primoriella the front of the glabella touches the roll-like border, causing it to slightly bulge forward, in Anabaraceps there is a roll-like preglabellar field as wide as the flat border in front of it, but in Schagonaria the glabella may or may not touch the frontal border, but neither the border, nor if present the preglabellar field is particularly convex.
The articulate middle part of the body (or thorax) has 16 segments.