Teinostoma parvicallum Pilsbry & McGinty, 1945, reaches only about 2 mm (0.08 inch) in diameter. The shell is smooth except for very faint growth lines, which are more noticeable around the suture, or the groove separating two successive whorls. There is a small callus (thickening) at the center of the umbilicus (the “hole” on the base of the shell).
As with many members of the micromollusk family Teinostomatidae, the shell color is translucent-white. This species is among the smallest found on Sanibel and Captiva islands. See post titled "The Allure of Small Size" in this blog for more on teinostomatids. (With many thanks to Dr Harry G. Lee for his unrestricted help with the identification of local vitrinellas and other Floridian micromollusks.) To learn more about “micros,” register for my upcoming (May 17) talk by Museum Curator José H. Leal, “Micromollusks-The Allure of Small Size”, at the National Shell Museum web site.
