Belongs within: Pseudomelatomidae.
Knefastia is a genus of large conoid gastropods found on the tropical west coast of the Americas (Powell 1966).
Characters (Powell 1966): Shell large, robust, 50–70 mm, biconic- fusiform, with tall turreted spire and moderately long, straight to slightly recurved anterior canal. Sculpture coarse with moderately high clasping adpressed suture, broadly rounded to angular prominent axials overridden by coarse spiral cords. Shell typically covered by thick periostracum. Sinus deep, U-shaped, occupying middle of shoulder slope. Operculum leaf-shaped with terminal nucleus. Radula with minute unicuspid vestigial central tooth and pair of modified “wishbone-type” marginals, in which distal limb of base is severed from rest of tooth.
<==Knefastia Dall 1919P66
|--*K. olivacea (Sowerby 1834)P66 [=Pleurotoma olivaceaP66, Turricula (Knefastia) olivaceaD19]
|--K. bajanensis (Usticke 1969) [=Fusiturricula (Knefastia) bajanensis]BC01
|--K. brooksvillensis Mansfield 1937P66
|--K. chira (Olsson 1931) [=Turricula (Knefastia) chira]P66
|--K. dalli Bartsch 1944P66
|--K. funiculata (Kiener 1839-1840)P66 (see below for synonymy)
|--K. glypta Gardner 1937P66
|--K. jaquensis (Sowerby 1850) [=Pleurotoma jaquensis]P66
|--K. lavinoides (Olsson 1922) [=Turricula lavinoides]P66
| |--K. l. lavinoidesP66
| `--K. l. limonensis (Olsson 1922) [=Turricula lavinoides limonensis]P66
|--K. nigricans (Dall 1919) [=Turricula (Knefastia) nigricans]P66
|--K. princeps Berry 1953P66
|--K. rossellae (Durham 1944) [=Clavatula (Knefastia) rossellae]P66
|--K. tuberculifera (Broderip & Sowerby 1829) [=Pleurotoma tuberculifera]P66
|--K. walkeri Berry 1958P66
`--K. waltonia Gardner 1937P66
Knefastia funiculata (Kiener 1839-1840)P66 [=Pleurotoma funiculataP66, Turricula (Knefastia) funiculataD19; incl. Clavatula griffithiiC64]
*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.
[C64] Carpenter, P. P. 1864. Supplementary report on the present state of our knowledge with regard to the Mollusca of the west coast of North America. Report of the British Association for the Advancement of Science 33: 517–686.
[D19] Dall, W. H. 1919. Descriptions of new species of mollusks of the family Turritidae from the west coast of America and adjacent regions. Proceedings of the United States National Museum 56 (2288): 1–86, pls 1–24.
[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.