Length: 2.8 - 4.5 mm
This unusual species boasts a "wavy" lateral margin when viewed dorsally. The elytra are striate while the pronotum is glossy and sparsely punctate. In some individuals the reddish color of the pronotum is very dark or even black.
Madarellus undulatus has been reported from Ontario and Quebec and much of the United States.
American Insects site