Shell very small (to 9.2 mm in total length), glossy, fusiform with a truncated anterior; whorls convex, peripheries below mid-whorl, last whorl large, approximately 58% of total length, asymmetrical, right side (viewed ventrally) swollen by varix; sculpture of low sigmoid ribs. Protoconch of 1,75-2 smooth whorls, the first mostly immersed in the second such that the shell's apex appears roundly blunt. Edge of protoconch lip distinct. Axial sculpture of opisthocline to sigmoid (on last whorl) ribs that extend from suture-to-suture on early but mostly obsolete in sulcus of later whorls; widest and highest on the whorl periphery, lower, thinner, and cordlike in sulcus; lower and narrower below whorl periphery, with traces to anterior fasciole. Light growth striae present, heaviest on last whorl. Sulcus marked by reduced or entirely absent ribs (in later whorls); ribs and growth striae curved reflecting outline of anal sinus. Varix is cup-handle-like just behind the anal sinus, about ¼-turn from the outer lip, 2-3 times larger than preceding ribs and straight, not oblique. Spiral sculpture absent except for weak spiral threads on the anterior fasciole. Outer lip thin, edge bent inward posteriorly. A narrow strengthening axial fold lies between the varix and edge of outer lip. Anal sinus on whorl's shoulder, deeply notched, apex round, angled away from shell's axis with by a large parietal lobe on one side and the slight outward inflection of the outer lip on the other. Sides of anal sinus divergent. Inner lip narrow; thickest on canal, thin, unemarginate on parietal wall, ending in a tubercle at anal sinus. Anterior canal straight, short and open; without a notch. Anterior fasciole not swollen, bearing 5-8 weak spiral threads. Color a uniform light golden brown, ribs lighter, almost white on some.

Cerodrillia brasiliensis has all of the diagnostic characteristics of Cerodrillia: a cup-handle-like varix just behind the anal sinus, spiral sculpture limited to the shell base and anterior fasciole; and ribs from suture-to-suture, which may be obsolete in sulcus of later whorls. Variability. Most of the 35 examined shells are fairly uniform; their average total length is 6.81 mm (5.6-9.2 mm) and average W/L ratio 0.397. The single specimen from off Guarapari, Espirito Santo, departs from the norm; it has very low, almost obsolete ribs that are represented by whitish nodes on the whorl shoulder. The nodes are connected by a faint white spiral line with a faint brown shadow line. This specimen is tentatively assigned here but may represent a separate species. Identification. Cerodrillia brasiliensis is not easily confused with known congeners. It is one of two other similar species, both in different genera, found offshore of southern Brazil: Bellaspira rosea, new species, and Lissodrillia cabofrioensis, new species. All three are similarly colored, small, and with weak axial sculpture. Cerodrillia brasiliensis differs from the other two in possessing a cup-handle-like varix typical of Cerodrillia, and axial ribs that run from suture-to-suture. Axials of B. rosea are very short, appearing on little more than the whorl periphery but axials of L. cabofrioensis end abruptly at the sulcus, do not extend to the suture as in C brasiliensis and B. rosea. Shell surface microsculpture also differs. Cerodrillia brasiliensis has spiral lines and grooves restricted to the shell base, L. cabofrioensis has none; B. rosea has spiral lines over most of the shell's surface.

Southern Brazil (Espirito Santo State; Rio de Janeiro State; Sao Paulo State). Absalao et al (2005) report C. clappi Bartsch & Rehder, 1939 in samples from off Rio de Janeiro, 22°48'43"S, 41°09'19"W, and from a station off the Espirito Santo/Bahia boundary area, 18°20'28"S, 38°55'34"W, that may be C brasiliensis on the basis of their description. Rios (2009: 314) reports what may be this species from off Sao Tome, Rio de Janeiro, Brazil. Examined specimens were reported from 20-150 m.