This species is characterized by its rather slender habit, appressed pubescence, thin-textured petiolate rather small leaves, inflorescences with the flowers subsessile on the primary axis, white corollas with tubes 5-6 mm long, and ovaries and fruits with 2 locules.

Gonzalagunia sagreana is similar to Gonzalagunia panamensis, with larger corollas and 4-locular fruits, and to Gonzalagunia cornifolia, also with 4-locular fruits. Gonzalagunia sagreana is also similar to Gonzalagunia dicocca of South America.