This European endemic species is assessed as Vulnerable (VU A3ce) due to a projected population decline estimated to be more than 30% over the next 15–30 years (which represents three generation lengths), from the potential impact of Batrachochytrium salamandrivorans (Bsal) on this species, and ongoing habitat loss and degradation that is occurring throughout its range.

This European endemic species is found in much of northern Iberia (mainland Spain and Portugal), and central, southern and western France. This species was introduced to the area of Turin, Italy, but is now presumed to be extinct there (J.W. Arntzen pers. comm.). It occurs from sea level to elevations approaching 2,100 m asl.

It is locally abundant in suitable habitats. It is locally endangered in central France, less threatened in southern France, and not particularly threatened in Portugal. In the 2008 assessment, it was reported to not be threatened in Spain. Since then declines caused by disease (Batrachochytrium salamandrivorans (Bsal)) have been recorded in Catalonia (Martel et al. 2020). Due to the ongoing decline in the extent and quality of its habitat and the effects of disease, the population is inferred to be decreasing. Extinction risk modelling for Bsal using subcriterion A3 predicts that at least 30% or more of the population will be lost within three generation lengths [15–30 years] (see the model in the attached Supplementary Information).

The generation length of this species is estimated to be between 5–10 years, and hence three generations is 15–30 years. It is conservatively estimated that Bsal will naturally advance at a rate of between 10–20 km per year. Therefore, a worst-case scenario of the impact of Bsal would be an outward spread of the disease from each current epicentre of 600 km (30 years at 20 km year), and the best case scenario would be an outward spread of 150 km (15 years at 10 km year). In the attached map (see Figure 5 in Supplementary Information), the inner circle around each epicentre has a radius of 150 km, and the outer circle has a radius of 600 km and shows the modelled spread of the disease. When overlaid on the current range of the species, the best case scenario has 10% of the range impacted, whereas the worst case scenario has 55% of the range impacted (see calculations in Supplementary Information). A good estimate of the projected decline due to Bsal in the next three generations for this species is the midpoint of these two scenarios which is 32.5%. Habitat loss and degradation are also likely to contribute to this decline hence a conservation estimate is that the species will decline by between 30–49% in the next three generations which qualifies it for Vulnerable status.

Aquatic habitats include well-vegetated ponds, pools, ditches and streams generally within dry woodlands, heathland, fields and rough grassland. It can occur in slightly modified habitats such as traditional farmland. Breeding and larval development take place in many different types of permanent and temporary water sources, usually with aquatic vegetation for reproduction.

Generation length is estimated to be 5–10 years (F. Pasmans pers. comm. July 2021).

Major threats are agricultural intensification, drainage, pollution, and eutrophication of aquatic habitats through intensive agriculture. Mass mortality of the species through disease (iridovirus) has been recorded in Carris Lake, Peneda-Gerês National Park, Portugal. The disease might be non-native and have been transferred to the lake by an introduced predatory fish (Lepomis gibbosus). Predation by L. gibbosus and other introduced predatory fish and crayfish (Procambarus clarkii) species are also a threat to Batrachochytrium salamandrivorans (Bsal) is an emerging fungal pathogen affecting amphibians and is closely related to B. dendrobatidis (Bd), which has had a devastating impact on amphibian populations around the world. Both pathogens cause the infectious disease chytridiomycosis, and both are believed to have originated in Asia (for Bsal: Martel et al. 2014, for Bd: O'Hanlon et al. 2018). While Bd can cause disease in frogs, salamanders and caecilians, Bsal has only been reported to cause disease in salamanders and newts, although the pathogen has been detected in some frog species(Martel et al. 2013). Bd has spread globally, but at present Bsal is only known in Asia and has been introduced to Europe, most likely through the pet trade in salamanders (Martel et al. 2014, Nguyen et al. 2017).

Currently in Europe, Bsal has been detected in the wild in the Netherlands, Belgium, Germany (e.g. Thein et al. 2020) and Spain (Martel et al. 2020), and has been shown to be highly pathogenic to most urodelan taxa in Europe (Martel et al. 2014). In March 2018, Bsal was detected in a reservoir in Montnegre i el Corredor Natural Park in Catalonia in northeast Spain, ca 1,000 km from the nearest known occurrence in Europe, and a mass mortality event was recorded in May 2018 of this species at that site (Martel et al. 2020). Bsal is considered to be a threat to this species, and this has been further confirmed in laboratory trials for susceptibility to Bsal which have also recorded a 100% mortality rate (F. Pasmans and A. Martel pers. comm. June 2021). The site in Catalonia was believed to be caused by the introduction of exotic newt species (Triturus anatolicus and Ichthyosaura alpestris) and is thought to be contained but not eradicated at present (Martel et al. 2020). Modelling (see Supplementary Information) has found this species to be at significant risk from Bsal in the next 15–30 years (which represents three generations).

This species is found in the national and international pet trade.

Conservation Actions In-Place
This species occurs in many protected areas. In Portugal, it is present in Peneda-Gerês National Park where the population of Carris Lake has been severely impacted by disease. It is also protected by national legislation throughout its range (Gasc et al. 1997), and is listed on Annex IV of the EU Natural Habitats Directive and Annex III of the Bern Convention. Re-introductions and/or translocations of this species have been made in the area of Madrid, Spain.

Conservation Needed
There is also an urgent need for a EU (European Union) wide coordinated approach and implementation of the Bsal Action Plan by Gilbert et al. (2020), which was commissioned by the European Commission.

Research Needed
Further research into the impacts of disease on this species is needed. In light of the threat of Bsal, the population should also be monitored especially if other outbreaks occur within its range.