Lonchodomas has five thorax segments and the pleural area of the pygidium has two narrow furrows.

Lonchodomas occurred in what are today Argentina, Canada (Newfoundland), Estonia, Latvia, Norway, Sweden, the Russian Federation (Leningrad Oblast[1]) and the United States (Oklahoma, Virginia).

The headshield (or cephalon) and tailshield (or pygidium) are subtriangular in outline.

Lonchodomas looks a lot like Ampyx but the glabella is diamond-shaped in outline, and it has a ridge along the midline (it is carinate).

The long median glabellar spine is subquadrate in section and is directed horizontally forward, from the frontal tip of the glabella.