[Photo: Texas Parks and Wildlife]

San Marcos Salamander
Eurycea nana

Description: The San Marcos salamander is a small and slender-limbed member of the Eurycea genus of the Lungless salamander family (Plethontidae). It grows up to 2.5 inches (6.4 cm) long and has a thin tail with a dorsal fin and 16-17 costal grooves. This species is reddish-brown in color with small yellow flecks on its back and a yellowish-white underbelly. This species can change to different shades of brown on its dorsal surface depending on the color of its surrounding substrate. It has small eyes with dark rings around them and external gills that are bright red in color, which it retains throughout life.

Life History: The San Marcos salamander lives and hunts in moss and algae. The dark reddish-brown color of the algae it inhabits almost perfectly matches the dark color on the dorsal surface of the San Marcos salamander. Breeding occurs throughout the year (peaking in late spring) and females lay eggs both singly or in small groups. It eats amphipods, small aquatic insects, and snails.

Habitat: The San Marcos salamander prefers to live on unsilted sand, gravel, or rocks from 1-8 inches (2.5-20 cm) in diameter with surrounding aquatic vegetation such as moss and matted, murky, floating algal mats. This species requires thermally and chemically constant, flowing water (70-72 degrees F [21-22 deg C]) that is clean and clear.

Distribution: Eurycea nana can be found from Spring Lake at the headwaters of the San Marcos River down to 0.5 miles below the Interstate 35 bridge, Hays County, central Texas.

The map below depicts the critical habitat for this species, as designated by the US Fish and Wildlife Service pursuant to the Endangered Species Act.

NOTE: No warranty is given, expressed or implied, as to the accuracy, reliability, or completeness of these data. Data do no represent a legal description of the critical habitat boundary; refer to the textual description in the appropriate final rule for this species as published in the Federal Register.

Federally Designated Critical Habitat for the San Marcos Salamander (Eurycea nana) [Figure: Houston Advanced Research Center using US FWS data]

Status: The San Marcos salamander is a state and federally listed (1980) threatened species. There is a refugium for this species at the San Marcos National Fish Hatchery and Technology Center. Quality and quantity of habitat is the most important requirement for maintaining a healthy population of San Marcos salamanders. The flow at which this species' habitat begins to decline is 80 cubic feet per second (cfs) or below. US Fish and Wildlife defines 60 cfs as the level for "take" of this species.

Resources:

Edwards Aquifer Authority, Draft Edwards Aquifer Habitat Conservation Plan

University of Texas, Herps of Texas, San Marcos Salamander

US Fish and Wildlife Service, Threatened Species Listing

US Fish and Wildlife Service, Endangered Species of the Edwards Aquifer

Texas Parks and Wildlife, San Marcos Salamander Species Profile