FWGSC > Promenetus exacuous

> Promenetus exacuous (Say 1821)

> Habitat & Distribution
The range of Promenetus exacuous extends from Atlantic to Pacific Coasts of North America, from New Mexico, Nevada, and northern Texas to the Arctic-Boreal Transition Zone in Canada (Burch 1989, Jokinen 1992). It occurs in quiet, shallow areas of lakes and rivers, as well as intermittent or permanent streams and ponds (Clarke 1981, Jokinen 1992, Jokinen 2005). Promenetus seems to be reaching the southern limit of its range in the Carolinas, being found sporadically in the Coastal Plain, sharing habitat with migratory birds.

> Ecology & Life History
This species is associated with living or decaying plant matter of autochthonous or allocthonous origins, and rarely occurs in the absence of these resources (Clarke 1981, Harman 1982, Jokinen 1983, Jokinen 2005). Substrata occupied include dead or living vegetation, mud, and occasionally rock (Clarke 1981, Jokinen 1992). Promenetus exacuous inhabits both soft- and hard waters (Jokinen 1983, McKillop 1985, Dillon 2000). Even in favorable situations, P. exacuous is rarely found in great abundance (McKillop 1985, Pip 1985, Pip 1991). However, it is a good disperser and readily colonizes vegetation-rich habitats (Jokinen 1987). The few life history studies focusing on this species revealed that P. exacuous is semelparous, with two cohorts produced each year (McKillop 1985, Jokinen 1992). Although P. exacuous occurs in eutrophic systems, it is sensitive to environmental degradation (Clarke 1979). Abundance and frequency of occurrence declined precipitously in southern Manitoba between 1978 and 1998 as intensive agriculture and other human land-use impacts increased (Pip 2000). Similarly, P. exacuous was extirpated between from Oneida Lake (New York State) between 1968 and 1992, with hypereutrophication presumably causing this local extinction (Harman 2000).

> Taxonomy & Systematics
Synonyms include Menetus exacuous, Menetus exacutus, and Planorbis exacutus (Stewart and Dillon 2004, Stewart in press).

> Essay
Promenetus was featured in a November 2005 essay I posted to the FWGNA group on the aerial dispersal of freshwater gastropods.

>Maps of Promenetus distribution
North Carolina
South Carolina

>References
Burch, J.B. (1989) North American Freshwater Snails. Malacological Publications, Hamburg, Michigan. Clarke, A.H. (1979) Gastropods as indicators of trophic lake stages. Nautilus 93:138-142. Clarke, A.H. (1981) The Freshwater Molluscs of Canada. National Museum of Natural Sciences, National Museums of Canada, Ottawa, Canada. Dillon, R.T., Jr. (2000) The Ecology of Freshwater Molluscs. Cambridge University Press, Cambridge, United Kingdom. Harman, W.N. (1982) Benthic substrates: their effect on fresh-water Mollusca. Ecology 53: 271-277. Harman, W.N. (2000) Diminishing species richness of mollusks in Oneida Lake, New York State, USA. The Nautilus 114:120-126. Jokinen, E.H. (1983) The Freshwater Snails of Connecticut. State Geological and Natural History Survey of Connecticut, Department of Environmental Protection Bulletin 109, Hartford, Connecticut. Jokinen, E.H. (1987) Structure of freshwater snail communities: species-area relationships and incidence categories. American Malacological Bulletin 5:9-19. Jokinen, E.H. (1992) The Freshwater Snails (Mollusca: Gastropoda) of New York State. New York State Museum Bulletin 482, Albany, New York. Jokinen, E.H. (2005) Pond molluscs of Indiana Dunes National Lakeshore: then and now. American Malacological Bulletin 20:1-9. McKillop, W.B. (1985) Distribution of aquatic gastropods across the Ordovician dolomite – Precambrian granite contact in southeastern Manitoba, Canada. Canadian Journal of Zoology 63:278-288. Pip, E. (1985) The ecology of freshwater gastropods on the southwestern edge of the Precambrian Shield. The Canadian Field-Naturalist 99: 76-85. Pip, E. (1991) Macrophyte and associated mollusc communities in a Meteor Crater Lake on the Precambrian Shield of Manitoba. The Canadian Field-Naturalist 105: 483-487. Pip, E. (2000) The decline of freshwater molluscs in southern Manitoba. The Canadian-Field Naturalist 114:555-560. Stewart, T.W., and R.T. Dillon, Jr. (2004) Species composition and geographic distribution of Virginia’s freshwater gastropod fauna: a review using historical records. American Malacological Bulletin 19:79-91. Stewart, T.W. (in press) The freshwater gastropods of Iowa (1821-1998): species composition, geographic distributions, and conservation concerns. American Malacological Bulletin.