Shell large (to 53 mm in total length), stoutly fusiform, anterior truncated; up to 13 whorls overall, teleoconch whorls turreted, the last approximately 56% of total shell length. Aperture a narrow oval, anterior canal short. Predominant sculptural element axial ribs. Protoconch of 2 smooth, round whorls. Axial sculpture of straight ribs, 13-15 on the penultimate, 9-11 on last whorl to varix, that run suture-to-suture on spire whorls, evanesce below periphery of last whorl; interspaces about equal to their width; rib crests ridged (not round) and almost blade-like and curved in sulcus reflecting outline of the anal sinus. Microscopic growth striae dense, visible between spiral threads and in sulcus. Varix large, hump-like, between ½ - 1/3-turn from edge of outer lip. Spiral sculpture of fine, more or less evenly spaced spiral cords that override ribs. Spaces separating cords wider than cord diameter; cords incised or grooved on their adapical side resulting in a saw-tooth (slanted adapically) formation; cords are weak in sulcus and on shell base. Sulcus concave, forming an acutely-angled shoulder. Outer lip thin, flattened from varix, but bent inward along its edge, strengthened by a few low axial folds; lip edge forms a low arc from anal sinus to stromboid notch and is scalloped by the ends of the spiral threads. Stromboid notch deep. Anal sinus deep, U-shaped, projects upward, appearing spout-like on account of the flared inner edge of sinus and slight outward curve of outer lip. Inner lip narrow, thick on anterior canal, thin on parietal wall, and posteriorly formed into a lobe. Layers of deposition visible on edge of anterior end of lip. Anterior canal short, open, twisted to the right when viewed ventrally; notched at its tip. Fasciole slightly swollen, twisted from rotation of canal during growth, with a chink between the fasciolar bulge and edge of inner lip. Boundary between fasciole and shell base marked by a low ridge, with spiral threads similar to those on shell base. Color white with 3 light orange to yellow spiral bands, the first is a row of spots on whorl shoulder between ribs, the second a broad band just below shoulder, and the last a narrow band just above anterior fasciole visible on shell base. Varix with a patch of slightly darker color than the bands.

Clathrodrillia petuchi has features characteristic of the genus: numerous narrow axial ribs that extend from suture-to-suture that are reduced and recurved in the sulcus, and strong spiral sculpture. Variability. The average total length of 12 fully developed specimens, which includes lengths of five reported in the literature that were not examined, is 42.13 mm (31-53.0 mm), their average W/L ratio is 0.390. Color banding varies in intensity among specimens, and nearly all-white specimens also occur (a faint color patch is present on varix shoulder). Identification. Clathrodrillia petuchi is similar to C. gibbosa (Born, 1778), but differs in being stockier, having wider and fewer ribs, and a different coloration, bands that are pale yellow to orange rather than brown. The varix also has a much lighter colored patch than in C. gibbosa. From C. colombiana, new species it differs in having fewer ribs (13-15 versus 18 on the penultimate whorl) and in having a different coloration, not the dark brown of C. colombiana. From Neodrillia blakensis (Tippett, 2007) it differs in possessing flat, turreted whorls, not convex ones, and straighter ribs.

Barbados; Guadeloupe; Martinique. Reported from 85-200 m.