Southwest Florida Shells with Emphasis on Sanibel & Captiva
José H. Leal
Costoanachis aff. sparsa
False Sparse Dove Snail
Shell size to 9 mm; spire elevated. Shell surface glossy, shiny. Axial sculpture of about 20, somewhat straight, narrow ribs. Spiral incised lines between ribs. Suture distinct. Outer lip denticulate. Color ivory-white to yellowish with a very regular pattern of reddish-brown markings. This species was identified in the 20th-century literature as C. sparsa, a similar but separate species (The "aff." in the species name indicates that the species "is similar to, but not the same species..." Shells from Southwest Florida differ ever so slightly from true C. sparsa, though, by details of the sculpture, including the deeply etched spiral lines below the suture (area separating two consecutive whorls). Also closely similar to C. similis (Ravenel, 1861) from the east coast of Florida. 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. The snail (two views) in the image measure about 8 mm (0.32 inch) was collected in early 2015 on Sanibel by Rebecca Mensch on stranded seaweed, and photographed by José H. Leal. The last image shows spent egg capsules on hydroid "branches."