Hydrobiid Snails (Mollusca: Gastropoda: Rissooidea) from St. Andrew Bay, Florida

Heleobops sp. of Hershler and Thompson appears to be the only previously published record for the gastropod family Hydrobiidae Troschel in tidal waters of the St. Andrew Bay System, Florida. Six species occurred in bayous, marshes, and brackish ponds associated with the System during studies conducted between 1984 and 1999: Texadina barretti (Morrison), Texadina sphinctostoma Abbott and Ladd, Littoridinops monroensis (Frauenfeld), Littoridinops palustris Thompson, Onobops jacksoni (Bartsch), and Heleobops sp. A. The last is an apparently undescribed species closely related to Heleobops carrikeri Davis and McKee. Based in part on this study, Heleobops sp. A, which occurs in brackish habitats from the System westward to the Chandeleur Islands, is considered conspecific with Heleobops sp. of Hershler and Thompson (1992) as well as Heleobops sp. Forms B and C of Heard (1992). There are two ecophenotypic shell types of Heleobops sp. A, a grayish-brown, smooth-shelled, intertidal variant and a tannish, light-orange, striate, subtidal form, which represent Forms B and C of Heard, respectively. In addition to constituting new records, the occurrence of T. barretti and T. sphinctostoma in the St. Andrew Bay System represents eastern range extensions for both species. Although their ranges encompass northwestern Florida, L. palustris and L. monroensis are reported from the System for the first time. The relatively large egg capsules of Heleobops sp. A, L. palustris, and L. monroensis each contain a single ovum, and, depending on temperature, generally require 9 to 14 days before hatching as juveniles. The egg capsules of T. barretti, T. sphinctostoma, and O. jacksoni also contain a single ovum per capsule, but their capsules are distinctly smaller, and, when maintained at room temperature for 5 to 8 days, eggs hatch into free-swimming, shelled-veligers. The distributions of other brackish water hydrobiids known from Florida and the Gulf of Mexico are briefly reviewed