Critically Endangered
San Marcos salamander
Eurycea nana
The San Marcos salamander is a small species of aquatic, lungless salamander native to the United States, endemic to Spring Lake and a small region of the headwaters of the San Marcos River near Aquarena Springs, in Hays County, Texas.
Appearance
The San Marcos salamander has a narrow head with a round snout, large eyes, and a dark iris. The species is uniformly light brown in color, with a series of seven to nine irregular light spots present along its midline. The trunk is flattened above with a dorsal furrow that extends from head to tail.
The size of the species was measured to be 56 millimetres (2.2 in) total in length. It is one to two inches long, with a slender body and external gills, and is reddish-brown in color.
Range and habitat
Spring Lake, that is the headwaters of the San Marcos River, located in Hays County, Texas, is the only known location of the San Marcos salamander. The population estimate in 1973 was about 20,880 salamanders living in the uppermost reaches of Spring Lake. An estimate in 1993 suggested about 30,451 salamanders across all ranges of Spring Lake and up to 150 metres (490 ft) downstream.
Pins are Wikidata “endemic to” fields. Orange dots, when present, are GBIF occurrence tiles — survey bias included.
Diet and breeding
The diet of E. Nana includes amphipods, fly larvae, and aquatic snails. San Marcos Salamanders typically follow a temporal diet, or a diet that varies with the availability of invertebrates present to them at a given time.
It relies on the schedule of invertebrate behavior and locations, and generally consumes many aquatic invertebrates. Site tenacity, the pattern of returning to the same nest or breeding site dependent on the season, was observed in both males and females of E. Nana.
In crisis
The San Marcos salamander has been federally listed as a threatened species since 1980. Due to its extremely limited geographic range, it is threatened primarily by the contamination of groundwater sources and heavy dependence of central Texas cities upon the Edwards Aquifer for water. Other threats include drying of the spring and introduced species.
Availability of food and sufficient prey also remain of concern for these salamanders, but less so than habitat loss or change. The San Marcos salamander and four other listed species are covered by the 1996 San Marcos/Comal (Revised) Recovery Plan, that includes recovery goals such as preserving the integrity and function of the aquifer and developing strategies to address both local and broad regional issues related to recovery.
Salamanders disappear when seeps are capped, caves are disturbed, or a pathogen moves through a mountain range.
San Marcos salamander is Critically Endangered on this catalog because that is the IUCN category stored on Wikidata. Confirm the official criteria and any later count on iucnredlist.org.
Sources
Written for this catalog from the English Wikipedia article on San Marcos salamander, Wikidata item Q33167. Family and order context is original field-guide writing about the group, not a copied assessment of this one species. Wikipedia text is CC BY-SA. Not an IUCN assessment. Counts, when quoted, can change — confirm them on the recovery programme and on iucnredlist.org.
