Post by sebbe67 on Apr 5, 2005 18:18:11 GMT
Pyrgulopsis coloradensis
Snail NV 1992 The Blue Point pyrg (Pyrgulopsis coloradensis) was collected in the 1970s, 1980s, and early
1990s at Blue Point Spring, Lake Mead Recreation Area, Clark County, Nevada [153].
Similar looking dead shells were found at Rogers Spring (1.25 miles to the southwest), but
the species which occurred there has been extirpated and its taxonomy can not be determined
[197]. Pyrgulopsis coloradensis was formally described in 1998 by Hershler, who reported
that it had "become increasingly scarce in the past decade" [242]. It has not been seen since
1992 despite surveys throughout the 1990s and early 2000s [197].
The cause of the extinction is not definitively known, but coincided with the post-1993
introduction of the red-rimmed thiara (Melanoides tuberculata) a predatory snail native to
Africa, Asia, and India commonly distributed through the aquarium trade [197]. Wild burros
have caused vegetative damage, but the habitat conditions appear adequate and not to have
degraded between 1993 and 2002 [197]. Rogers Spring was impounded for recreational
swimming long prior to the 1990s destroying it ability to sustain Pyrgulopsis coloradensis if
species ever occurred there. Rogers Spring has also contained various predatory cichlid
species over the past 40 years.
Snail NV 1992 The Blue Point pyrg (Pyrgulopsis coloradensis) was collected in the 1970s, 1980s, and early
1990s at Blue Point Spring, Lake Mead Recreation Area, Clark County, Nevada [153].
Similar looking dead shells were found at Rogers Spring (1.25 miles to the southwest), but
the species which occurred there has been extirpated and its taxonomy can not be determined
[197]. Pyrgulopsis coloradensis was formally described in 1998 by Hershler, who reported
that it had "become increasingly scarce in the past decade" [242]. It has not been seen since
1992 despite surveys throughout the 1990s and early 2000s [197].
The cause of the extinction is not definitively known, but coincided with the post-1993
introduction of the red-rimmed thiara (Melanoides tuberculata) a predatory snail native to
Africa, Asia, and India commonly distributed through the aquarium trade [197]. Wild burros
have caused vegetative damage, but the habitat conditions appear adequate and not to have
degraded between 1993 and 2002 [197]. Rogers Spring was impounded for recreational
swimming long prior to the 1990s destroying it ability to sustain Pyrgulopsis coloradensis if
species ever occurred there. Rogers Spring has also contained various predatory cichlid
species over the past 40 years.
