Shell very small (to 7.8 mm total length), fusiform, with up to approximately 7,25 glossy whorls, sutures appressed, the last whorl approximately 58% of the shell's total length. Whorls convex below sulcus, sculpted by bold, rounded axial ribs. Protoconch conical, of approximately 1,75 glossy-smooth whorls, the first not immersed in the second. Axial sculpture of broad, round-crested opisthocline ribs that are reduced on whorl shoulder, obsolete in sulcus on last whorl, where they evanesce on shell base below whorl periphery. Ribs are spaced about the same as their width, 7 on the penultimate, 5 on the last whorl to the varix. Growth striae are very fine. Spiral sculpture consists of fine ridges on shell base and anterior fasciole. Shell surface microsculpture, as viewed under a dissecting microscope, consists of groups of 1 or more very fine threads separated by a single somewhat wider but still microscopic space. SEM images of the shell surface show that the pattern of narrow threads and wide spaces is created by groups of closely spaced rows of punctae (in the image about 5-6 rows) separated by wider spaces where punctae are sparse and placed randomly. Sulcus narrow, concave, with low and slightly arcuate ribs. Varix larger than preceding rib, cup handle-like, within Vi-turn of edge of outer lip. Outer lip edge thin and produced in a low arc from the anal sinus to a weak stromboid notch anteriorly. A strengthening fold is located near the edge of the outer lip of the holotype (outer lip missing on paratypes). Anal sinus located on the shoulder, deep, U-shaped with a slightly flared inner edge; offset from the wall by a parietal callus; sides parallel. Inner lip thin, recumbent, "pinched" erect anteriorly, thin and unemarginate in parietal area; parietal callus at posterior end weak, forming one side of anal sinus. Anterior canal short but well defined, curved to the right when viewed ventrally, unnotched; anterior fasciole not swollen, with about 6-9 fine spiral threads. Color white to off-white, protoconch darker on holotype, the best specimen.

Cerodrillia arubensis has the characteristics of the genus: a glossy shell with spiral sculpture confined to the anterior portion of the shell base and anterior fasciole, a sulcus with reduced ribs, obsolete on last whorl, a varix within 1/4-turn from the edge of the outer lip, and a short but well defined anterior canal. The coarse microsculpture is somewhat unusual compared to other members of the genus, but differs from examined specimens of Decoradrillia, Fenimorea, and Splendrillia (compare with SEMs in Plates 49, 62 & 130-131, respectively). Where present, most of its congeners have fainter spiral lines. Like most members of the genus, its shell is nearly monochromatic. Variability. The average total length of three specimens is 7.33 mm (7.0-7.8 mm), and average W/L is 0.395. Little variability in form and color is exhibited by this small sample size. Identification. Splendrillia stellae, new species, is very similar and also found in Aruba but differs in having a smooth, narrower shell without spiral microsculpture except for spiral ridges on anterior fasciole, a varix hump-like about 1/3 turn from edge of outer lip, and a shorter anterior canal.

Known only from Aruba. Its habitat is also unknown because specimens were taken from beach drift or harbor dredgings.