Elongate mud meadows springsnail (Pyrgulopsis notidicola)
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2 BIOLOGICAL INFORMATION Pyrgulopsis notidicola is a member of the family Hydrobiidae, which consists of approximately about100 species of small freshwater gastropods found in the western United States. Although few studies have been conducted on species within the genus Pyrgulopsis (springsnails) in the Great Basin, general knowledge about their natural history exists. Pyrgulopsis are small (usually less than 5 millimeters [0.2 inches (in.)] high, are tightly linked with their aquatic habitat, and often are endemic to single bodies of water (particularly springs), or local drainage features (Hershler 1998). Pyrgulopsis are widespread within the Great Basin where they occur in a variety of relatively small, usually fishless, spring-fed water bodies. This genus also historically occurred in a few Great Basin lakes; none have been found in rivers. Pyrgulopsis springsnails only occupy permanent springs because they cannot survive outside an aquatic environment. Therefore, extant populations are in aquatic habitats that have persisted for long periods of geological time (Taylor 1985). It is uncommon for a spring to be occupied by more than one species of springsnail. Pyrgulopsis often decline dramatically in density downstream from spring sources, presumably reflecting their requirement for the well-known stable temperature, chemistry, and flow regime characterized by headsprings (Deacon and Minkley 1974). They feed on algae gleaned from the substrate and aquatic vegetation, and they occupy habitats with good water quality. Although they may occupy a number of different substrates, most species prefer either sand, gravel, or cobble (Deacon and Minkley 1974). There have been no studies on the life history of the Great Basin species. Pyrgulopsis notidicola was described by Hershler (1998) and is distinguished from three other species in the Soldier Meadow area by its more elongate shell with short spire; larger and more disjunct aperature; well-developed columellar shelf; smaller, globose bursa copulatrix; penis with larger terminal gland; and very weak ventral gland. Pyrgulopsis notidicola is endemic to Soldier Meadow, which is located at the northern extreme of the western arm of the Black Rock Desert in the transition zone between the Basin and Range Physiographic Province and the Columbia Plateau Province, Humboldt County, Nevada. This region is characterized by cold, dry winters influenced primarily by cool, polar air masses, and by hot, dry summers influenced primarily by warm, tropical air masses (Nachlinger 1991). Soldier Meadow lies between the Calico Mountains to the west and the Black Rock Range to the east, and encompasses a province of approximately 50 thermal, connected and isolated springs in an alluvial basin at the northwestern terminus of the Black Rock Desert about 121 kilometers (km) [75 miles (mi)] north of Gerlach, Nevada and 16 km (10 mi) south of the Summit Lake Paiute Indian Reservation. The vegetation is broadly classified into four wetland communities and three upland communities, one of which is considered transitional. The wetland communities support a tremendous diversity of plants, with over 60 different species identified in the marshes, seeps, and meadows. Thermal springs occur in the area at elevations ranging from 1,320 and 1,393 m (4,330 and 4,570 ft) (Nachlinger 1991). Some of the springs provide the only known habitat for the desert dace (Eremichthys acros), a federally-listed species endemic to approximately 20 springs in Soldier Meadow (Knight 1990).
http://frwebgate5.access.gpo.gov/cgi-bin/waisgate.cgi?WAISdocID=681311318978+4+0+0&WAISaction=retrieve[Federal Register: May 11, 2005 (Volume 70, Number 90)] [Proposed Rules] [Page 24869-24934] From the Federal Register Online via GPO Access [wais.access.gpo.gov] [DOCID:fr11my05-19] Page 24869 DEPARTMENT OF THE INTERIOR Fish and Wildlife Service 50 CFR Part 17 Endangered and Threatened Wildlife and Plants; Review of Native Species That Are Candidates or Proposed for Listing as Endangered or Threatened; Annual Notice of Findings on Resubmitted Petitions; Annual Description of Progress on Listing Actions AGENCY: Fish and Wildlife Service, Interior. ACTION: Notice of review. ... Elongate mud meadows springsnail (Pyrgulopsis notidicola)--The following summary is based on information contained in our files. No new information was provided in the petition received on May 11, 2004. Pyrgulopsis notidicola is endemic to Soldier Meadow, which is located at the northern extreme of the western arm of the Black Rock Desert, in the transition zone between the Basin and Range Physiographic Province and the Columbia Plateau Province, Humboldt County, Nevada. The type locality, and the only known location of the species, occurs in a stretch of thermal (between 45[deg] Celsius (C) (113[deg] Fahrenheit (F)) and 32[deg] C (90[deg] F)) aquatic habitat that is approximately 300 m (984 ft) long and 2 m (6.7 ft) wide. Pyrgulopsis notidicola occurs only in shallow, flowing water on gravel substrate. The species does not occur in deep water (i.e., impoundments) where water velocity is low, gravel substrate is absent, and sediment levels are high. The present or threatened destruction, modification, or curtailment of its habitat or range by recreational bathers in the thermal waters is the greatest threat to the species. The small size of their habitat and their limited range makes them highly susceptible to any factors that negatively impact their habitat. Regulatory mechanisms are beginning to be put in place, but few actions have been implemented to date. Based on imminent threats of high magnitude, we retain a listing priority number of 2 for this species.