Jollyville Plateau salamander  (Eurycea tonkawae)

Classified as Endangered (EN) on the IUCN Red List (1).

The Jollyville Plateau salamander (Eurycea tonkawae) belongs to an unusual group of salamanders that retain their gills and other larval features into adulthood. A small aquatic salamander species the Jollville Plateau salamander has a broad head, flat snout and large well-developed eyes. Its body is dark greenish-brown, with a translucent underside. The adult has three pairs of gills behind red-coloured jaws, a yellow, diamond-shaped mark on its head and well-developed, bright yellow-orange tail fins (2). The Jollyville Plateau salamander was only recently named as a separate species from the closely related Texas salamander (Eurycea neotenes).

The Jollyville Plateau salamander is found only in Texas, USA, in the Jollyville Plateau region northwest of Austin, where it is known from just six stream drainages (2).

Typically inhabiting springs, the Jollyville Plateau salamander is usually found in relatively shallow, well-oxygenated water with a cobble, gravel or rocky substrate, which is used for cover (3) (4). Some populations provisionally assigned to this species have also been found in caves (2).

The Jollyville Plateau salamander is unusual in retaining its larval features, such as external gills as an adult. It doesn’t undergo metamorphosis into a terrestrial adult form, instead remaining aquatic throughout its life (1) (4) (5).

The Jollyville Plateau salamander preys on small aquatic invertebrates, particularly larvae and snails, but little else is known of its feeding habits (4).

Although the Jollyville Plateau salamander is likely to reproduce throughout the year, juveniles are most commonly seen from March to August (4) (5). It is thought that the Jollyville Plateau salamander deposits its eggs in gravel substrate in a similar manner to other closely-related species in central Texas. The small, juvenile Jollyville Plateau salamander is most likely to be found in shallow water at the stream edge, as it prefers thinner substrate (4).

The major threat that the Jollyville Plateau salamander faces is urbanisation, which is expanding rapidly in Austin, Texas (2) (4) (5). The abundance of this salamander has been found to decrease as the degree of urbanisation increases (2) (4). One site that the Jollyville Plateau salamander inhabits has been affected by building work resulting in increased levels of nitrate (4). This has coincided with an increase in recordings of spinal deformities in the Jollyville Plateau salamander population (2). This species is also likely to be affected by other forms of pollution, including from chlorinated water from swimming pools (3) (4). In addition to pollution, the habitat of the Jollyville Plateau salamander is being degraded by altered water flow (3) (5), including increased flow rates due to discharges from urban areas which can wash away the salamanders or the cover upon which they depend (3). As they are small and localised, the freshwater springs this species inhabits are also susceptible to drying and drainage (2).

As the Jollyville Plateau salamander has only recently been discovered, there is little information of its historical abundance. Studies are being conducted into the relationship between salamander abundance and distribution and habitat and water quality in order to devise policies for their protection (5). Long-term monitoring of water quality and continued surveys of this species have also been recommended (4).

In addition, further studies may be needed to determine whether certain populations of the Jollyville Plateau salamander should be classified as separate species (1) (2).

Some populations of the Jollyville Plateau salamander fall within the City of Austin Preserves and is potentially within the Travis County Audubon Sanctuary (2). This salamander is also a candidate species for listing as ‘endangered’ under the U.S. Endangered Species Act (USFW). However, the future of this rare amphibian remains uncertain (2), and will depend on the preservation of its habitat an on controlling the rate of urbanisation within its range (5).

To find out more about the Jollyville Plateau salamander and other amphibians:

Amphibia web
http://amphibiaweb.org/