Turrancilla williamsoni Petuch 1987

“ Turrancilla” williamsoni Petuch, 1987 (Fig. 21F–H) “ Turrancilla ” williamsoni Petuch 1987: 104–105, pl. 25, figs 1–2. Type material. Holotype USNM 784573. Type locality. Off Punto Fijo, Gulf of Venezuela, Venezuela, 35 m. Remarks. Petuch (1987) attributed the species to Turrancilla without any discussion. The species is known only from the empty shell of the holotype, and its taxonomic position remains unclear. However, it differs from other Turrancilla species in several aspects. First, it was collected at much shallower depths (35 m), while the shallowest occurrence of Turrancilla spp. is around 200 m, typically below 350 m, and as deep as 1855 m. Second, in other Turrancilla species, the suture is overlaid by a thick secondary callus, rendering it invisible from the exterior; its position can only be inferred from a shallow depression. In contrast, in “ T. ” williamsoni, the suture, though overlaid by a relatively thinner callus, is clearly visible. Third, the olivoid groove is very distinct, while the olivoid band is relatively much narrower than in Turrancilla species that exhibit a very weak groove (T. akontistes and T. reboriae). Finally, the secondary callus forms a distinct keel-like thickening just above the suture, which is absent in studied Turrancilla species. Conversely, features of “ T. ” williamsoni are found in various Amalda species (see, e.g., Kantor et al. 2020), which, in the Western Atlantic, are known to inhabit a similar depth range (Malacolog 4.1.1 – Rosenberg 2009). Thus, in the absence of data on the operculum and radula, we conditionally reassign the species to the genus Amalda.