FWGNA > Species Accounts > Ancylidae > Laevapex fuscus
Laevapex fuscus (C. B. Adams 1841)

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> Habitat & Distribution

This limpet is widespread on rocks and woody debris in gently-flowing or cooler waters  throughout North America east of the Great Plains, from Florida to southern Ontario and Quebec (Basch 1963, Clarke 1981, Walther et al. 2006).  Laevapex populations are more common in larger and mid-sized rivers with calmer waters, and are not typically found in smaller and rockier streams.   FWGNA incidence rank I-5.

> 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.

Jokinen's (1987) analysis of the distribution of L. fuscus in Connecticut and New York led her to classify it as a “High-S” species, found only in the most species-rich communities.  Dillon’s (2000: 360-363) reanalysis of these data confirmed the Undifferentiated life history adaptation suggested by the earlier stufy of McMahon.

> Taxonomy & Systematics

The shells of Laevapex vary in outline from elliptical to nearly circular.  Those in the latter category have sometime been assigned to the nomen L. diaphanus (Haldeman 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, nor are the more recent nomina peninsulae (Pilsbry & Johnson 1903) or arkansasesis (Walker 1917).  See my essay of 20July07 from the link below.

> Supplementary Resources [PDF]

> Essays 

> References

Basch, P. (1959)  The anatomy of Laevapex fuscus, a freshwater limpet.  Misc. Publ. Mus. Zoology Univ. Mich. 108: 1 - 56.
Basch, P. (1963)  A review of the recent freshwater limpet snails of North America. Bull. Mus. Comp. Zool. Harvard, 129, 399-461. 
Clarke, A. H. (1981)  The Freshwater Molluscs of Canada.  National Museums of Canada, Ottawa.  445 pp.
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.
Jokinen, E. (1987) Structure of freshwater snail communities: Species-area relationships and incidence categories.  Amer. Malac. Bull. 5: 9 - 19.
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.
Russell-Hunter, W. D. & R. F. McMahon (1976)  Evidence  for functional protandry in a freshwater limpet, Laevapex fuscus.  Trans. Amer. Micros. Soc. 95: 174 - 182.  
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. 6.