Body very narrow and elongate, shining black; the markings differing a little in the two sexes. In the male the head has a groove in front, which is wanting in the female. In the latter the thorax is somewhat contracted in the middle, and in both sexes it has a groove extending from the middle to the base. The elytra are scarcely wider tnan the base of the thorax, deeply grooved near the suture, and marked with punctured lines on the sides, each of them with two narrow lines of reddish yellow. The anterior thighs are furnished with a small tooth on the under side. Like all the other species of the genus, this insect lives under bark, and is often found on the stems of old trees congregated in hundreds.