1. Department of Biology, University of Texas Rio Grande Valley, Edinburg, TX 78542 USA
2. Texas Fish and Wildlife Conservation Office, United States Fish and Wildlife Service, San Marcos, TX 78666 USA
3. Aquatic Resources Center, United States Fish and Wildlife Service, San Marcos, TX 78666 USA
4. Edwards Aquifer Research and Data Center, Texas State University, San Marcos, TX 78666 USA