Posted: Apr 20 2007

Turbonilla (Pyrgiscus) rixtae de Jong & Coomans, 1988

This shell was originally described by C. B. Adams, 1851 and named Truncatella modesta. Adams was working with a specimen missing the protoconch. Although reassigning correctly to the subfamily Turbonillinae with a new name, de Jong & Coomans used Adams’ description. “Yellowish horn colour with white upper margin of the whorls, with about 21 prominent compressed ribs, and numerous spiral striae, spire with the outlines somewhat curvilinear, whorls 7 (after truncation), moderately convex, margined above.” de Jong & Coomans reported specimens “with less ribs.” Redfern reported T. rixtae from Abaco, Bahamas. He described it as “To 5.25 mm,” stocky, convex whorls with about 20 axial ribs that cross the periphery and fade out on the base. Impressed spiral lines that become dominant as the ribs fade on the base. Redfern reports his Abaco shells as “chalky white,” but does not indicate if any were live-collected. My live-collected specimen fits Adams’ description of “Yellowish horn colour with white upper margin of the whorls” and my dead-collected specimens fit Redfern’s “chalky white.”

As far as I know these specimens are the only records of this species in Florida. I’d certainly like to hear from others who believe they have found T. rixtae.

Sorry about how dirty these specimens are,

but when I have few I don't like to take the

risk of damage by cleaning.

Blind Pass, St. Petersburg Beach, Pinellas Co.,

FL.   4 mm    Photos by Marlo Krisberg

Here's the only other specimen I've collected (Dead-collected at Tarpon Springs, Hillsborough County. 2.8 mm):