Cythara coniformis is a species of sea snail, a marine gastropod mollusk in the family Mangeliidae.
This species is considered a nomen dubium.
The length of the shell attains 9 mm.
The thin, whitish shell is rather transparent. It is faintly plicate on the upper part of the whorls and transversely very faintly striated.
This marine species occurs off Hawaii, United States.