San Marcos Salamander
The San Marcos salamander is listed by USFWS and TPWD as threatened. It is a member of the lungless salamander family. It retains its juvenile form, including features such as gills, in the adult sexually mature-stage of the life cycle. The gills expand and appear bright red from increased blood flow due to the cool temperature and low oxygen content of the water in which it lives. In addition, it does not leave the water to metamorphose into a terrestrial form, but becomes sexually mature and breeds in the water. San Marcos salamanders are small, slender, and light brown in color with yellowish fl ecks. The salamander is capable of altering its dorsal coloration from light tan to dark brown in conformity with the color of the substrate.
Up to 2.3 inches long.
San Marcos Springs aquatic ecosystem. The San Marcos salamander is restricted to the headwaters of the San Marcos River, in proximity to the major spring openings. They are primarily located on limestone shelves in the shallow, rocky spring areas of Spring Lake, downstream from San Marcos Springs. The salamander requires clean, clear, and thermally constant flowing waters in areas of sand, gravel, and rock substrate with filamentous algae or vegetation for cover, in areas with little mud or detritus. In addition, the area preferred by the salamander must provide an adequate food supply of small insect larvae, insect pupae, and small aquatic snails.