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The Roswell springsnail, scientific name Pyrgulopsis roswellensis, is a species of small freshwater snail, an aquatic gastropod mollusk in the family Hydrobiidae. This species is endemic to Roswell, New Mexico in the United States.

Physical Characteristics
Roswell springsnails (Pyrgulopsis roswellensis) are aquatic mollusks currently found only in Roswell, New Mexico (New Mexico Game and Fish). These endangered snails are small, ranging in size between 3-3.55mm in length (Taylor, 1987). Adult snails have internal gills, a protective gill cover called an operculum,, and a narrow, conical shell. Their shell has a series of 5 shell spirals. The Roswell springsnail has an amber operculum. This distinguishes Roswell springsnails from other local springsnails, such as the Koster’s springsnail.

Despite the overall high genetic diversity within this species, there is low genetic diversity within each distinct population (New Mexico Department of Game and Fish). Genetic diversity describes how many different types of alleles, or traits, exist within a population. High diversity between populations implies that each population is relatively isolated from one another. Low diversity within groups can be problematic as high diversity helps species adapt to changing environments.

Life History and Reproduction
Roswell Springsnails have an average life-span of 9-15 months. Their reproduction has not been studied in-depth, but research suggests their breeding patterns are similar to other snails in the hydrobiid genus. Hydrobiid snails are sexually dimorphic, with male and female snails differing in external appearances. Males are distinguishable due to the presence of the non-retractable verge, or the male copulatory organ, which is visible near the neck. Breeding season takes place between the months of March and September. Roswell springsnails, as well as Koster’s springsnail, are unique from the hydrobiid genus because they are ovoviviparous.

Behavior
Roswell springsnails tend to prefer gypsum rich substrates. Despite their preference, springsnails can be found on a variety of other substrates. They are mostly active during twilight time periods. Little else is known about this species’ behavior (U.S. Fish and Wildlife Service Recovery Plan).

Diet
The diet of Roswell springsnails consists of algae, bacterium, fungi, and detritus.

Habitat
Because the Roswell Springsnail is a fully aquatic species of snail, this species requires permanent, clean freshwater between 10-20°C. The snails can tolerate moderately saline water. The snails also need food sources and substrates like organic silts, limestone cobble, and gypsum (Designation of Critical Habitat for Roswell Springsnail, Federal Register).

Roswell springsnail habitat includes wetlands, karsts, sinkholes, and springs. Because of Roswell's limestone geography, there are numerous underground water features. Much of the snail’s habitat are fed by groundwater springs, which often start in unprotected areas.

The species can tolerate dissolved oxygen conditions of ~1ppm to over 20ppm (from surveys in 1995-98) and pH ranges of 6.7-8.2. Specific temperature conditions and tolerance ranges vary depending on the site. These snails can also persist under drought conditions (NMDGF 2011).

Distribution
The largest population is in Bitterlake National Wildlife Refuge in Roswell, NM. Other locations include the Roswell Country Club (NM), Pecos County (TX), and Reeves County (TX). The snail is endemic and lacks a widespread habitat. However, current populations appear stable.

Historic and Present Range

 * 1981: Snail at North Spring (Roswell Country Club) in 1967-71, 1973 (Landeye)
 * 1987: “Five locations of Roswell springsnail were known when the species was described in 1987 (Taylor). All of these occurred within Chaves County, and three of them were located outside BLNWR.”
 * 1992: Unit 7 ditch desiccated. North Spring (Roswell Country Club), Sago Springs run, & Sinkhole 32 (Mehlhop).
 * 1993: Population densities estimated at North Spring and Sago Springs. 1,125 to 27,924/m2 at Sago Springs.
 * 1995-1996: Population density 64 to 512/m2 at Bitter Creek.
 * 1997-1998: Population density 27,000/m2 at Sandhill pre-fire.
 * 2000-2003: Population density 5,000/m2 at Sago Springs post-fire.
 * 2002: Populations persisted in Unit 7 despite dry conditions.
 * 2004: Not found in surveys.
 * 2005: Listed as endangered.
 * 2009: “Current distribution of Roswell springsnail appears to be restricted to BLNWR and at a location recently found on City of Roswell property near the BLNWR boundary (Sanchez).”
 * 2011: Final critical habitat designated: Bitterlake NWR (Roswell Basin), Roswell Country Club (City of Roswell), Toyah and Coganosa Basins.

Status and Conservation
In 2002, the U.S. Fish and Wildlife Service (USFWS) proposed listing the Roswell springsnail as "endangered with critical habitat under the ESA of 1973. The Roswell springsnail was listed because of its decreasing population size. Noel's amphipod, the Pecos assiminea and the Koster's springsnail were listed as well. These three freshwater invertebrates share similar habitats with the Roswell springsnail. The proposed rule also designated the species’ wetland and karst habitats as critical habitats (Proposed Rule 67 FR 6459, 2002).

In September 2005, the USFWS officially listed all four species as endangered under the Endangered Species Act (Rule 70 FR 46303, 2005). In 2011 the USFWS designated critical habitat for the Roswell springsnail at BLNWR, Roswell Country Club, and the Toyah and Coganosa Basins. The four invertebrates currently remain endangered (U.S. Fish and Wildlife Service, 2019).

The IUCN Red List listed the Roswell springsnail as vulnerable (VU) in 2012. This listing is due to the snail’s limited distribution and possible future threats. Historically, the IUCN listed it as indeterminate (I) in 1994 and Data Deficient (DD) in 1996 (Cordeiro, J. 2012).

Estimated Population Density
Springsnails usually occur in fairly high densities, despite their limited geographic distribution (Johnson et al., 2014) In 1993, the estimated population densities for the springsnails (combining both Roswell and Koster’s springsnails) were 1,390 individuals per m2 (129 per ft2 ) at the Roswell Country Club and 9,560 per m2 (888 per ft2) at Sago Springs in BLNWR. At Sago Springs, Roswell springsnails had an average abundance of 27,000 per m2 (2,508 per ft2 ) in 1997-1998, increasing to 65,000 per m2 (6,039 per ft2 ) in 2000-2003 after the Sandhill Fire. As of Summer 2015, the combined densities of the Koster’s and Roswell springsnails were 26,175 per m2 at Bitter Creek, 17,000 per m2 at Sago Springs, and 5,574 per m2 at Snail Unit, all within BLNWR (U.S. Fish and Wildlife Service, 2019). It should be noted that population densities vary significantly throughout the year and consistent, year-round surveys are needed to accurately report the population sizes (Johnson et al., 2019). Currently, the Roswell springsnail populations appear stable (U.S. Fish and Wildlife Service, 2019).

Historical Distribution
The Roswell springsnail was first documented in 1967 at the Roswell Country Club. By 1987 five separate locations of Roswell springsnails were identified. All five locations were within the bounds of Chaves County, NM. Three of these locations were outside of BLNWR. In 2011 the USFWS designated two locations at BLNWR as critical habitat for the Roswell and Koster’s springsnail.

As of 2017, there are five known populations of Roswell springsnails, all within BLNWR. There is not enough data to determine if there are currently Roswell springsnail populations outside of the refuge.

Wildlife management agencies conduct species reviews every five years to track listed species. These reviews look at species biology, habitat conditions, implemented conservation measures, and threat status (Notice 84 FR 36113, 2019). The most recent five-year review for the Roswell springsnail occurred in 2019. The New Mexico Department of Game and Fish currently lists the Roswell springsnail with a moderate degree of threat and a high potential for recovery (U.S. Fish and Wildlife Service, 2019).

Roswell springsnails are largely protected from direct human impact because of their habitat. There is no known economic value for these snails, as they are not consumed for food. There is the potential that these snails will become desirable for collectors, but this would not make a significant impact on the population (Personal communication with Dan Trujillio, NMDGF).

Habitat degradation is a major threat for the Roswell springsnail. Groundwater pumping, chemical spills, and algae blooms all contribute to habitat loss. Climate change also poses a threat. Increasing temperatures and changing weather patterns could impact the snails' habitat (U.S. Fish and Wildlife Service, 2019).

Current conservation efforts include careful management and continuing research on the species. There is still much that is unknown about the species. The springsnail's specific diet, ecosystem niche, toxicology, and fecundity are currently undetermined. With all known Roswell springsnail populations occurring on federally protected land, this species is currently well protected, despite imminent threats (Personal communication with Dan Trujillio, NMDGF).