Shell small for genus, elongated, fusiform, with high, elevated spire; suture indented and spire whorls distinctly scalariform; shoulder rounded; body whorl and spire whorl with 3 large, rounded, winglike varices; elongated, rounded, bladelike longitudinal rib present between each pair of varices on body whorl; body whorl with 4 large, rounded primary spiral cords and single thinner secondary cord anterior of four primaries; spire whorls with 2 large spiral cords; siphonal canal narrow, well developed, ornamented with large, rounded spiral cord; intricalx chalky, microscopically pitted; aperture proportionally large, flaring, oval in shape; inner lip smooth; parietal shield proportionally large, adherent; shell uniformly cream-white. Holotype: Length 10 mm, width 5 mm, FMNH 328409; Paratype: length 10 mm, same locality as holotype, in the research collection of the author.

The new Belizean muricid, with its three wing-like varices and large bladelike intravarical ribs, is unlike any other known living western Atlantic Dermomurex species. Of the Atlantic members of its genus, Dermomurex coonsorum is most similar to D. sarkini E. Vokes, 1992, an early Pleistocene fossil species from the Moin Formation of Costa Rica. Although similar in size and general shape, D. coonsorum differs from the fossil D. sarkini in being a more elongated, narrower, and less inflated shell; in having a more rounded shoulder and varices; and in having only four primary spiral cords instead of five. At present, the new muricid is known only from Glover's Atoll, Belize, to where it may be endemic.

Type Locality: In tide pool at low tide (with hermit crab), outer barrier reef of Southeast Cay, Glover's Atoll, Belize.