Pyrgulopsis bruneauensis


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Pyrgulopsis bruneauensis
Species Authority: Hershler, 1990
Common Name(s):
English Bruneau Hot Springsnail

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(ii,iii,v)+2ab(ii,iii,v) ver 3.1
Year Published: 2012
Date Assessed: 2012-03-05
Assessor(s): Cordeiro, J.
Reviewer(s): Bohm, M., Collen, B. & Seddon, M.
Contributor(s): Seddon, M., Dyer, E., Soulsby, A.-M., Whitton, F., Kasthala, G., McGuinness, S., Milligan, HT, De Silva, R., Herdson, R., Thorley, J., McMillan, K., Collins, A., Offord, S., Duncan, C. & Richman, N.
Pyrgulopsis bruneauensis has been assessed as Critically Endangered as the species is found in one location with an extent of occurrence of significantly less than 100 km2 and an area of occupancy of 8 km2.  Agricultural use of groundwater has led to the disappearance of springs in the area which means that the species is experiencing a continued decline in habitat quality as springs continue to reduce in number and size, as well as a continued decline in the area of occupancy. Disappearance of springs will ultimately reduce the number of mature individuals found within the population.  A greater knowledge of life history patterns would allow observed population declines to be assessed against criterion A, as observed declines are likely to also qualify the species for Critically Endangered under criterion A. Habitat protection and management will be necesasry to ensure the stabilisation of the subaquifier and thus the survival of the species.
2000 Critically Endangered
1996 Data Deficient

Geographic Range [top]

Range Description: This species is only known from 89 of the 155 small geothermal springs along an 8 km reach of the Bruneau River and its tributary Hot Creek in southwestern Idaho, USA (USFWS 2007). The extent of occurrence is therefore significantly less than 100 km2. With abstraction of water being the primary threat to the persistence of the springs which this species inhabits, the geothermal springs are all affected by a single instance of this threat, i.e. are all one location.
United States (Idaho)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: There are natural fluctuations in the density of this species ranging from 1,782 per m2 to 8,900 per m2 (Mladenka and Minshall 2001). However, there has been a substantial decline in the number of occurrences of this species with springs declining at a rate of 3.75 per year (Myler et al. 2007) and a population decline of approximately 96% within a ten year period (USFWS 2007). The generation length for this species is unknown preventing an accurate population decline for criterion A from being inferred, however it is likely to be under 3 years, suggesting a population decline which also meets the A criteria for CR.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This species is collected from thermal springs where it is found on rocks, mud, gravel and algal film (USFWS 2002).
Systems: Freshwater

Use and Trade [top]

Use and Trade: This species is not utilised.

Threats [top]

Major Threat(s): The primary threat to this species is loss of habitat (springs) as a result of groundwater abstraction for agriculture. This has already resulted in significant drawdown of the aquifer which is now resulting in the loss of approximately 3.75 springs per year (Myler et al. 2007).

Conservation Actions [top]

Conservation Actions: This species has been given a Global Heritage Status Rank of G1 (critically imperiled) by NatureServe (2009). Further research of life history traits will help to determine a more accurate estimate of population decline for the species while site protection and management of the Bruneau River will facilitate the survival of the species by ensuring a sustainable subaquifier level is maintained.

Citation: Cordeiro, J. 2012. Pyrgulopsis bruneauensis. The IUCN Red List of Threatened Species. Version 2015.2. <>. Downloaded on 31 August 2015.
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