Belongs within: Drilliidae.
The type subgenus of the genus Drillia is an assemblage of high-spired conoid gastropods with a truncated body whorl typically ending in a false umbilicus (Powell 1966).
Characters (Powell 1966): Shell moderately large, 25–30 mm, very solid, elongate-conic, with tall spire but truncated body-whorl, which terminates in bulging twisted fasciole, pronounced false umbilical cavity, and very short but deeply notched anterior canal. Protoconch narrowly conic of three smooth whorls, tip small. Adult sculpture of heavy broad but narrowly crested oblique axial ribs, which commence at shoulder angle and extend over base to fasciole. Spiral sculpture of numerous weak flat-topped cords, with incised linear interspaces. Shoulder slope smooth except for sinus-curve growth lines. Outer lip thin-edged but strengthened behind by varicose axial. Sinus on shoulder slope, moderately deep, U-shaped, with spout-like reflected rim, somewhat constricted by very heavy parietal callus pad. Most of parietal callus free along outer edge. Very distinct stromboid notch, low on outer lip. Radula prototypic, with minute unicuspid central, crescentic comb-like lateral and elongated, sharply pointed, but not barbed, marginal. Operculum leaf-shaped, with terminal nucleus. Colour uniformly buff, dull surfaced, often rust-brown stained, but aperture and callus porcellanous white.
<==Drillia Gray 1838 (Drillia)BC01
|--*D. (D.) umbilicata Gray 1838 [=Pleurotoma umbilicata]P66
|--D. (D.) acapulcana (Lowe 1935)PP78
|--D. (D.) angolensis Odhner 1923P66
|--D. (D.) ballista Maltzan 1883P66
|--D. (D.) bruuni Knudsen 1952P66
|--D. (D.) cydia Bartsch 1943 [incl. Inodrillia ustickei Hayes in Usticke 1959]BC01
|--D. (D.) dakarensis Knudsen 1956P66
|--D. (D.) distincta Thiele 1925P66
|--D. (D.) dunkeri Knudsen 1952P66
|--D. (D.) falsa Barnard 1958P66
|--D. (D.) monodi Knudsen 1952P66
|--D. (D.) nicklesi Knudsen 1956P66
|--D. (D.) paucinoda Douvillé 1933P66
|--D. (D.) pyramidata (Kiener 1839-1840) [=Pleurotoma pyramidata]P66
|--D. (D.) rosacea (Reeve 1845) [=Pleurotoma rosacea; incl. P. (Drillia) rosolina Marrat 1877]P66
|--D. (D.) tripter Maltzan 1883P66
`--D. (D.) tumida McLean & Poorman 1971BC01
*Type species of generic name indicated
References
[BC01] Boyko, C. B., & J. R. Cordeiro. 2001. Catalog of Recent type specimens in the Division of Invertebrate Zoology, American Museum of Natural History. V. Mollusca, part 2 (class Gastropoda [exclusive of Opisthobranchia and Pulmonata], with supplements to Gastropoda [Opisthobranchia], and Bivalvia). Bulletin of the American Museum of Natural History 262: 1–170.
[PP78] Poorman, F. L., & L. H. Poorman. 1978. Additional molluscan records from Bahía de Los Angeles, Baja California Norte. Veliger 20 (4): 369–374.
[P66] Powell, A. W. B. 1966. The molluscan families Speightiidae and Turridae: an evaluation of the valid taxa, both Recent and fossil, with lists of characteristic species. Bulletin of the Auckland Institute and Museum 5: 1–184, pls 1–23.