Reaching only up to 9 mm (0.35-inch), this dove snail (family Columbellidae) in the genus Costoanachis is found locally (Southwest Florida) in shallow water, among seaweeds and sometimes seagrasses. The species, however, apparently has not been named: in the past, some authors called it Costoanachis sparsa (Reeve, 1859), but this latter species is something else. The shell is glossy, with about 20 narrow, somewhat straight ribs. The ribs are constricted by a number of fine spiral lines, forming beaded nodules. Background color is ivory to yellowish with a pattern of reddish-brown markings. The mantle and foot of the live animal are whitish with brownish-gray blotches. The tentacles and siphon are of same colors, but the blotches become rings around those structures.
An Unnamed Dove Snail, shell and live animal in ventral and dorsal views, from Sanibel. Photos by José H. Leal.