Paradrillia is a genus of conoid gastropods found in the Indo-Pacific region, with a fossil record going back to the Miocene (Powell 1966; previous CoO posts on conoids can be found here, here, here and here). Species of Paradrillia are small shells, about one to three centimetres in length, with a relatively tall spire and short siphonal canal. The sculpture on the outside of the shell usually consists of nodular spirals; the operculum is leaf-like, with a terminal nucleus. The long, awl-shaped radular teeth are trough-shaped in cross-section (Kilburn 1988).
The classification of Paradrillia has shifted around over the years, like most of the less differentiated conoids that were lumped by Powell (1966) under the heading of 'Turridae'. Powell (1966) classed them as Turriculinae, Kilburn (1988) transferred them to the Stictispirinae. Kilburn also synonymised Powell's separate genera Paradrillia and Vexitomina. Powell had distinguished them on the basis that Paradrillia supposedly had an operculum with a mediolateral nucleus instead of the terminal nucleus of Vexitomina. However, this was based on a single specimen that Kilburn regarded as teratological after he found terminal nuclei in Paradrillia melvilli. Most recently, Paradrillia was placed by by Bouchet et al. (2011) on the basis of molecular data in their new family Horaiclavidae.
Bouchet, P., Yu. I. Kantor, A. Sysoev & N. Puillandre. 2011. A new operational classification of the Conoidea (Gastropoda). Journal of Molluscan Studies 77: 273-308.
Kilburn, R. N. 1988. Turridae (Mollusca: Gastropoda) of southern Africa and Mozambique. Part 4. Subfamilies Drilliinae, Crassispirinae and Strictispirinae. Annals of the Natal Museum 29 (1): 167-320.
Powell, A. W. B. 1966. The molluscan families Speightiidae and Turridae: An evaluation of the vaid taxa, both recent and fossil, with lists of characteristic species. Bulletin of the Auckland Institute and Museum 5: 1-184.