Type locality: Big Bay, Espiritu Santo, Vanuatu . Description Shell small, fusiform (W/H 0.38, A/H 0.51), thin-walled, with high last adult whorl and moderately long, straight siphonal canal Protoconch missing: teleoconch of ca 6% whorls, suture adpressed. First teleoconch whorl rounded, sculptured with few opisthocline ribs; subsequent whorls with progressively more flattened profile. Sculpture of very low, barely discernible orthocline ribs, intersected by wide, flattened cords, better pronounced on last three whorls. Adapical cord separated from abapical portion of whorl by narrow but deep, continuous groove; subsequent cords separated by shallower, punctate grooves, with axially aligned pits marking position of otherwise indiscernible axials. Penultimate whorl with 5 cords; last whorl with flattened adapical portion (bearing 4 cords), followed by convex periphery sculptured with 6 cords, and evenly concave shell base gradually extending to siphonal canal. Cords count on base and canal 8, somewhat narrower than on periphery, separated by deeper grooves. Aperture elongate, lacking both a siphonal notch and an apical callous pad; outer lip thin and fragile, evenly convex along adapical 3/4 of its height, inside with 8 widely set lirae. Inner lip with well developed white callus; columella with four, fine, rather low, folds. Shell surface unpolished, with thin periostracum, and very fine collabral growth lines; background color beige with irregular, vague, darker blotches subsuturally and at periphery; inside of aperture white. Radula of about 57 transverse rows of teeth. Rachidian with rather broad base and three pointed cusps, rather closely set at slightly elevated central portion of rachidian. Laterals sickle- shaped with one long cusp Etymology The species epithet refers to the characteristic shape of the spire, which differentiates it from the morphologically closest species. Distribution South China Sea, Solomon Islands, Vanuatu Remarks Costapex pyramidalis sp. nov. is very similar in shell morphology to C.joliveri , and the two have broadly overlapping distributions. Costapex pyramidalis sp. nov. and C. joliveti share a sculpture on late whorls dominated by broad, flattened cords, and similar color patterns. However, C. pyramidalis seems to have a more flattened whorl profile, resulting in the overall more biconical shell. compared to the somewhat more ovate C. joliveti. Another aspect of this difference is the outline of the last whorl, which is more evenly convex in C. joliveti, and with a more pronounced concavity at the transition of shell base to siphonal canal. However, due to the small number of available specimens, we cannot test how reliable is this difference between the two species, and so DNA data remain important for their identification. C. martinorum and C. baldwinae have a notably stronger spiral sculpture compared to C. pyramidalis sp. nov., whereas, conversely, C. levis is distinguished by the complete lack of sculpture on late teleoconch whorls.