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Southwest Florida Shells with Emphasis on Sanibel & Captiva

By José H. Leal

Family Vermetidae

Petaloconchus nigricans

(Dall, 1884)

Dark Worm Snail

Tube worm similar to Petaloconchus varians, with long shelly tubes sculpted with longitudinal ridges, forming massive structures. The largest cluster examined from Sanibel in the National Shell Museum Collection was found by Michael Reardon on the beach off West Gulf Drive, in September 2016. The cluster illustrated measures 23 cm, and the largest shell aperture diameter in this cluster is about 3 mm (see detail photo). Dr. Rüdiger Bieler of the Field Museum of Natural History identified the specimen and indicated that the species is very likely just a tightly aggregated growth form of the widespread species P. varians (d'Orbigny, 1839).