> Laevapex fuscus (C. B. Adams 1841)

> Habitat & Distribution
This limpet is found throughout eastern North America, from Florida to southern Ontario and Quebec.  In southern Atlantic drainages it is widespread from the mountains to the coast, generally on woody debris in calm water.

> Ecology & Life history
McMahon (1975) reported simple annual life cycles (type A) for two L. fuscus populations in New York, and two generations per year (Bii) in a third. The bioenergetic data collected by McMahon suggest that reproductive effort in this species is in line with expectation from adult weight, and hence that their life history strategy is Undifferentiated (Dillon 2000: 126 - 135).  Jokinen’s (1985) Connecticut population of L. fuscus also displayed a type-A cycle.

> Taxonomy & Systematics
The shells of Laevapex in the Carolinas vary in outline from elliptical to nearly circular.  Those in the latter category have sometime been assigned to the nomen L. diaphanus (Hald. 1841).  Much of this morphological variation is certainly ecophenotypic, however (McMahon 2004).  The recent research of A. Walther and her colleagues (2006) confirms that L. diaphanus is not genetically distinct from L. fuscus.

> Essay
See my 20July07 post to the FWGNA group for a review of the 2006 paper by Walther et al., with a note on "phylogenetic sporting."

> Maps of Laevapex distribution
Click the small map to enlarge it, or download the state-specific PDFs



North Carolina (PDF)

South Carolina (PDF)

Georgia (PDF)

> References
Basch, P. (1963)  A review of the recent freshwater limpet snails of North America. Bull. Mus. Comp. Zool. Harvard, 129, 399-461.  Dillon, R. T., Jr. (2000)  The Ecology of Freshwater Molluscs.  Cambridge University Press, United Kingdom.  509 pp.  Hubendick, B. (1964) Studies on Ancylidae, The subgroups.  Meddelanden Fran Goteborgs Musei Zoologiska Avendelining, 137.  (Goteborgs Kungl. Vetenskaps-Och Vitterhets-Samhalles Handlingar.  Sjatte Foljden. Ser. B.) 9, 1-72.  Jokinen, E. (1985)  Comparative life history patterns within a littoral zone snail community. Verh. Internat. Verein, Limnol., 22: 3292-3399.  McMahon, R.F.  (1973) Respiratory variation and acclimation in the freshwater limpet, Laevapex fuscus.  Biol. Bull. 145: 492-508.  McMahon, R. F. (1975)  Growth, reproduction and bioenergetic variation in three natural populations of a freshwater limpet Laevapex fuscus (Adams). Proc. Malac. Soc. Lond., 41: 331-351.  McMahon, R. F. (1976)  Growth, reproduction and life cycle in six Texan populations of two species of fresh-water limpets.  Am. Midl. Nat. 95: 174-185.  McMahon, R. F. (2004)  A 15-year study of interannual shell shape variation in a population of freshwater limpets (Pulmonata: Basommatophora: Ancylidae).  Am. Malac. Bull. 19: 101-109.  Walther, A. C., T. Lee, J. B. Burch, & D. O'Foighil (2006)  E Pluribus Unum: A phylogenetic and phylogeographic reassessment of Laevapex (Pulmonata: Ancylidae), a North American genus of freshwater limpets.  Molec. Phyl. Evol. 40: 501 - 516.