The Atlantic drainages of Georgia, comprising approximately 40% of the waters of the state, are presently covered... ›› more
The four ecoregions of North Carolina drain toward the Atlantic through six major river systems... ›› more
Although perhaps not as environmentally heterogeneous as neighboring states, South Carolina does include... ›› more
The survey reported here is focused on the eastern 75% of the state, draining from the Blue Ridge to the Atlantic... ›› more
All waters draining into the Tennessee River above the Alabama line, including SW Virginia, W North Carolina, and N Georgia... ›› more
A study area of approximately 150,000 km2, including Delaware, Maryland, New Jersey, eastern Pennsylvania and the West Virginia panhandle... ›› more
A survey of all waters draining into the Ohio River upstream from the mouth of the Tennessee/Cumberland at River Mile 920... ›› more
> 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
Adams (1841) originally described fuscus in the genus Ancylus, which was grouped into the subgenus Laevapex by Walker (1903) and raised to the full genus level by Basch (1959a, b, c).
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.
> Maps and Supplementary Resources
- Laevapex distribution in drainages of The Ohio (2019)
- Ancyid distribution in Atlantic drainages (2023)
- Laevapex distribution in the Tennessee/Cumberland (2022)
- Virginia species account with county distribution
> Essays
- See my 20July07 post to the FWGNA group for a review of the 2006 paper by Walther and colleagues, "Phylogenetic Sporting and the Genus Laevapex."
- See my post of 26Sept14 for good, comparative figures illustrating "The egg masses of freshwater pulmonate snails."
- See my essay of 11Jan17 for an interesting photo of Laevapex on the back of a Belostomatid bug - "A previously unrecognized symbiosis?"
> References
Basch, P. (1959a)
the anatomy of Laevapex
fuscus, a fresh-water limpet (Gastropoda: Pulmonata).
Misc. Publ. Mus. Zool. Univ. Michigan 108: 1 - 56.
Basch, P. (1959b)
Studies on the development and reproduction of the
fresh-water limpet Ferrissia
shimekii (Pilsbry). Trans. Amer. Micros. Soc.
78: 269 - 276.
Basch, P. (1959c)
Status of the genus Gundlachia
(Pulmonata: Ancylidae). Occ. Pprs. Mus. Zool. Univ. Michigan 602: 1 - 9.
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.
Walker, B. (1903)
Notes on eastern American ancyli. Nautilus 17: 13 -
19, 25 - 31.