Wet-rock Physa
Photo Copyright Ann Buddenhagen
Physella zionis
NatureServe conservation status
Global (G-rank): G1
State (S-rank): S1
Utah Wildlife Action Plan status
- SGCN
External links
Phenology
"...copulation occurs during winter, spring, and summer, that eggs and youg occur throughout the year, and the P. zionis overwinters principally in rock fissures and as 1 mm long juveniles, but that some adults also overwinter." (U91CLA01UTUS).
Species range
Wet-rock physa only exists in Utah, specifically in Zion National Park.
Habitat
This species inhabits seeps and "hanging gardens," mainly on the vertical sandstone walls of the narrow canyons through which the North Fork of the Virgin River flows (Pilsbry 1926, Ng and Barnes 1986). These wet canyon walls are covered with algae (Pilsbry 1926), and the "hanging gardens" are composed of such plants as maidenhair ferns, cardinal flowers, and columbines (Whipple 1987). Gregg (1940) found several colonies of this species on "[w]et faces of cliffs" and one colony "on horizontal surfaces of large flat rocks at the base of the cliff as well as on the perpendicular surface of the cliff."
Ecology
Some researchers have observed robins preying on the snails (U83DNG01UTUS).
Reproductive characteristics
Copulation during winter, spring and summer (U91CLA01UTUS).
Threats or limiting factors
Threats to wet-rock physa include: predation, natural disasters, water usage and management, and tourism and recreation.
Taxonomy
This species was described and named by Pilsbry (1926) as PHYSA ZIONIS, and this name was used by Jones (1940) as well as Gregg (1940) and Ng and Barnes (1986). Chamberlin and Jones (1929) elevated the subgenus that Pilsbry (1926) had established solely for this species to generic status and thus arranged this species as PETROPHYSA ZIONIS, a name also used by Chamberlin and Roscoe (1948).
Ng (1983), Ng and Barnes (1986), and Whipple (1987) called this species "the Zion snail". Clarke (1991) referred to it as the "Zion tadpole snail". (This is one of the few mollusks that Chamberlin and Jones [1929] discussed without providing a common name.)