> Habitat & Distribution

Baker (1911) gave the range of L. elodes (together with all its probable synonyms) as extending from the Arctic Circle to “the neighborhood of the 40th parallel” in the East, approximately the latitude of Philadelphia.  And indeed, museum collections do seem to suggest that 100 years ago, L. elodes populations were not uncommon in the vicinity of Philadelphia, extending through Maryland into northern Virginia.  But today L. elodes is rarely recorded below the glacial maximum, at the approximate latitude of New York City.  FWGNA incidence rank in our 17-state Eastern database is I-4.

Baker's "40th parallel" rule works better in The Great Plains, where L. elodes is much more common, ranking #4 in incidence (of 33 species).  Populations are widespread in Nebraska and The Dakotas, but do range as far south as Kansas.

Lymnaea elodes is “ubiquitous” in Canada, according to Clarke (1981).  Typical populations inhabit swamps, marshes, vernal ponds and similar aquatic habitats of an isolated or temporary nature, usually rich in organic debris.  The thesis research of Flowers (2013), however, suggested that at least some populations of L. elodes can inhabit large and permanent lakes, there adopting a shell morphology difficult to distinguish from L. catascopium.  See my essay of 3Sept15 from the link below for more. 

> Ecology & Life History

Most populations of L. elodes seem to display annual life cycles (type A of Dillon 2000: 156-162), burrowing into loose organic matter during dry or cold conditions, emerging with the spring rains to grow and reproduce rapidly (Jokinen 1978, Brown 1979, Byrne et al. 1989).  The Indiana population designated “F” by Brown and colleagues (1988) was classified as R-adapted by Dillon (2000: 148) based on its high reproductive output relative to body size, and semelparous reproduction.  The distributional data tabulated by Jokinen (1983) for Connecticut populations of L. elodes also suggested R-adaptation to Dillon (2000: 360-364).

Other populations, perhaps inhabiting ponds not quite as productive, display type G life cycles, surviving to reproduce a second year (Hunter 1975).  Canadian populations may require two years to mature (life cycle Hs, McKillop 1985).  The data on reproductive energetics developed by Hunter (1975) suggested to Dillon (2000: 126 – 136) that three New York populations of L. elodes were USR Undifferentiated with respect to life history adaptation.

The natural diet of L. elodes seems directed toward the larger-bodied algae and the tissues of living macrophytes (Bovbjerg 1965, 1968, Hunter 1980) and away from detritus (Brown 1982).  Lymnaea elodes itself seems to be a target food item for a great variety of predators, including waterfowl (Swanson & Meyer 1977), crayfish (Hanson et al 1990), and sciomyzid flies (Eckblad 1973b).  The experiments of Brown & DeVries (1985) suggested that predation by fish such as mudminnows (especially at the egg and juvenile stages) may be a primary determinant of L. elodes distribution.

Populations of L. elodes have figured in a great many influential studies of aquatic ecology, including those of Eisenberg (1966, 1970), Hunter (1975, 1980), K. M. Brown (1979, 1982, 1985a, Brown & DeVries 1985, Brown et al. 1988), Cuker (1983a, b) and Hershey (1990, 1992).  Interested researchers are referred to the bibliography below for a variety of excellent studies on the population and community ecology of these most valuable model organisms.

> Taxonomy & Systematics

Basommatophoran gastropods of the worldwide family Lymnaeidae are characterized by striking conchological diversity but anatomical uniformity.  The mounting evidence that much of the shell morphological variation upon which lymnaeid systematics have been based seems to arise from ecophenotypic plasticity (e.g., Bronmark et al. 2011, 2012, Terry & Duda 2021) has led to a great deal of taxonomic churn.

Thomas Say described Lymnaeus elodes in 1821 from “Canandaigua Lake," see my essay of 19Aug15 from the link below for more.  Many other lymnaeid populations differing only slightly in shell morphology were described by other authors throughout the 19th century, so that by 1911 Frank Collins Baker recognized 24 dark, slender, marsh-dwelling species in a "Group of palustris."  Baker's "Group" was headed by the European Lymnaea palustris (Muller 1774), the range of which he considered circumboreal, and included such other well-known taxa as elodes, reflexa, exilis, neopalustris and traski.

Hubendick (1951) lumped all 24 of these nomina (and a great many Old World nomina as well) under the single nomen palustris.  Walter (1969) suggested that all the New World “stagnicolines,” including both the dark, slenderly-shelled taxa of ponds and marshes and the pale, more obesely-shelled taxa of lakes and rivers, be combined under the single nomen L. catascopium. 

In the last 60 years evidence has mounted, however, that the Eurasian populations Hubendick combined under palustris may represent as many as five cryptic species (see my essay of 23Apr12 from the link below).  This prompted Burch (1989) to recognize multiple species in his “Stagnicola elodes group” here in North America, including elrodiana, exilis, neopalustris and traski as well as elodes, leaving L. palustris as a taxon strictly of the Old World.

Modern molecular phylogenies seem to confirm the distinction between L. elodes and L. palustris, suggesting a closer relationship between American elodes and populations now known as L. occulta in Eastern Europe or L. tarebra in Russia (Correa et al. 2010).  DNA sequence data do not, however, suggest much divergence between L. elodes and any of the other nominal North American stagnicolines, including members of the emarginata/catascopium group, which almost all workers (except H. J. Walter) have always considered distinct.  See my essay of 4June12 from the link below for more.

Most recently, the observations of Brady & Turner (2010), together with the MS thesis of Flowers (2013) and phenotypic plasticity studies of Terry & Duda (2021), have supported a two-species model for the North American stagnicolines, best identified as L. elodes and L. catascopium.  Populations of both species seem to bear pale, fat shells in large lakes and dark, slender shells in vernal ponds.  See my essay of 3Sept15 for more.

> Maps and Supplementary Resources

• Lymnaea elodes distribution in Atlantic drainages (2023)
• Lymnaea distribution in drainages of The Ohio (2019)
• Lymnaea distribution in The Great Plains (2024)
• The V1 shell form of Brady & Turner is bona fide L. elodes.  The V2 form seems best identified as L. catascopium.  See my essays of 10May12 & 3Sept15 below.
  

> Essays

• See my post to the FWGNA blog of 28Dec06 for a review of The Classification of the Lymnaeidae.
• The taxonomy of the Old World stagnicoline lymnaeids has long been entangled with that of the New.  In my post of 23Apr12 I reviewed the work of Jackiewicz and others on the cryptic species of Lymnaea palustris, and the light this research may shed on the evolutionary relationships of the North American stagnicoline fauna in general.  See “The Lymnaeidae 2012: Tales of L. occulta.”
• See my post of 10May12 for a review of some unpublished (but nevertheless fascinating) observations on the shell morphology of L. elodes populations inhabiting NW Pennsylvania, “The Lymnaeidae 2012: Tales from the cryptic stagnicolines.”  That essay also included a couple photos of the living snails, courtesy of Andy Turner.
• On 9July12 I reviewed a paper by Bronmark and colleagues (2011) offering a marvelous insight into shell phenotypic variance of the sort I had just featured on 10May12: “The Lymnaeidae 2012: A clue.”
• As of 4June12 a stack of 21 molecular phylogenetic studies of the Lymnaeidae worldwide had accumulated on my desk.  Here’s my effort to make sense of it all: “The Lymnaeidae 2012: Stagnalis yardstick.”
• See my post of 26Sept14 for good, comparative figures illustrating "The egg masses of freshwater pulmonate snails."
• See my post of 19Aug15 for an (ultimately rather frustrating) expedition to find The Type Locality of Lymnaea elodes.  That particular essay also featured a scan of Say's lovely (1830ish) figure.
• On 3Sept15 I reviewed The Lost Thesis of Samantha Flowers, at long last bringing a bit of clarity to the tangled systematics of the North American stagnicoline lymnaeids, if you have the patience to wade through it.

> References

Baker, F. 1911. The Lymnaeidae of North and Middle America, Recent and Fossil. Special Publication No. 3., Chicago: Chicago Academy of Natural Sciences.
Boag, D. 1981. Differential depth distribution among freshwater pulmonate snails subjected to cold temperatures. Can. J. Zool. 59: 733-737.
Boag, D. and J. Bentz. 1980. The relationship between simulated seasonal temperatures and depth distributions in the freshwater pulmonate, Lymnaea stagnalis. Can. J. Zool. 58: 198-201.
Bovbjerg, R. 1965. Feeding and dispersal in the snail Stagnicola reflexa (Basommatophora: Lymnaeidae). Malacologia 2: 199-207.
Bovbjerg, R. 1968. Responses to food in lymnaeid snails. Phys. Zool. 41: 412-423.
Brady, J. K & A. M. Turner 2010.  Species-specific effects of gastropods on leaf litter processing in pond mesocosms.  Hydrobiologia 651: 93-100.
Bronmark, C., T. Lakowitz, and J. Hollander. 2011. Predator-induced morphological plasticity across local populations of a freshwater snail. PLoS ONE 6(7): e21773.
Bronmark, C., T. Lakowitz, P. Nilson, J. Ahlgren, C. Lennartsdotter, and J. Hollander. 2012. Costs of inducible defense along a resource gradient. PLoS One 7(1): e30467.
Brown, K. 1979. The adaptive demography of four freshwater pulmonate snails. Evolution 33: 417-432.
Brown, K. 1982. Resource overlap and competition in pond snails: an experimental analysis. Ecology 63: 412-422.
Brown, K. 1985a. Intraspecific life history variation in a pond snail: The roles of population divergence and phenotypic plasticity. Evolution 39: 387-395.
Brown, K. 1985b. Mechanisms of life history adaption in the temporary pond snail Lymnaea elodes (Say). Am. Malacol. Bull. 3: 143-150.
Brown, K. and DeVries, D. 1985. Predation and the distribution and abundance of a pond snail. Oecologia 66: 93-99.
Brown, K., B. Leathers, and D. Minchella. 1988. Trematode prevalence and the popluation dynamics of freshwater pond snails.  Am. Midl. Nat. 120: 289-301.
Burch, J. B. 1989  North American Freshwater Snails.  Malacological Publications, Hamburg, MI.  365 pp.
Byrne, R., J. Reynolds, and R. McMahon. 1989. Shell growth, reproduction and life cycles of Lymnaea peregra and L. palustris (Pulmonata: Basommatophora) in oligotrophic turloughs (temporary lakes) in Ireland. J. Zool. (Lond.) 217: 321-339.
Clarke, A. H.  1981.  The Freshwater Molluscs of Canada.  Ottawa: National Museums of Canada.  445 pp.  
Correa, A. C., J. S. Escobar, P. Durand, F. Renaud, P. David, P. Jarne, J-P Pointier, & S. Hurtrez-Bousses. 2010.  Bridging gaps in the molecular phylogeny of the Lymnaeidae (Gastropoda: Pulmonata), vectors of Fascioliasis.  BMC Evolutionary Biology 10: 381.
Cuker, B. 1983a. Grazing and nutrient interactions in controlling the activity and composition of the epilithic community of an arctic lake. Limnol. Oceanog. 28: 133-141.
Cuker, B. 1983b. Competition and coexistence among the grazing snail Lymnaea, Chironomidae, and microcrustacea in an arctic epilithic lacustrine community. Ecology 64: 10-15.
Dillon, R. T., Jr. 2000.  The Ecology of Freshwater Molluscs.  Cambridge University Press 509 pp.
Eckblad, J. 1973. Experimental predation studies of malacophagous larvae of Sepedon fuscipennis (Diptera:Sciomyzidae) and aquatic snails. Exp. Parasitol. 33: 331-342.
Eisenberg, R. 1966. The regulation of density in a natural population of the pond snail, Lymnaea elodes. Ecology 47: 889-906.
Eisenberg, R. 1970. The role of food in the regulation of the pond snail, Lymnaea elodes. Ecology 51: 680-684.
Flowers, S. L. 2013.  Inferences into species delimitation of Nearctic Stagnicola (Gastropoda: Lymnaeidae) using geometric morphometric and phylogenetic methods.  M.Sc. Thesis, University of Michigan, Ann Arbor.
Forbes, G., and H. Crampton. 1942. The effect of population density upon growth and size in Lymnaea palustris. Biol. Bull. 83: 283-289.
Hanson, J., P. Chambers, and E. Prepas. 1990. Selective foraging by the crayfish Orconectes virilis and its impact on macroinvertebrates. Freshw. Biol. 24: 69-80.
Hershey, A. 1990. Snail populations in artic lakes: competition mediated by predation? Oecologia 82: 26-32.
Hershey, A. 1992. Effects of experimental fertilization on the benthic macroinvertebrate community of an arctic lake. J. NABS 11: 204-217.
Hubendick, B. 1951. Recent Lymnaeidae.  Their variation, morphology, taxonomy, nomenclature, and distribution. Kungl. Svenska Vetensk. Akad. Handl., 3, 1-223.  
Hunter, R. 1975. Growth, fecundity, and bioenergetics in three populations of Lymnaea palustris from upstate New York. Ecology 56: 50-63.
Hunter, R. 1980. Effects of grazing on the quantity and quality of freshwater aufwuchs. Hydrobiologia 69: 251-259.
Jokinen, E. H. 1977.  The formation and structure of the shell varix in Stagnicola elodes (Say)  The Nautilus 91: 13 – 15.
Jokinen, E. H. 1978. The aestivation pattern of a population of Lymnaea elodes (Say) (Gastropoda: Lymnaeidae)  Amer. Midl. Natur. 100: 43-53.
Jokinen, E. 1983. The Freshwater Snails of Connecticut. State Geol. Nat. Hist. Survey Bull. 109, Hartford, Connecticut. 83 p.
Jokinen, E. 1987.  Structure of freshwater snail communities: species-area relationships and incidence categories. Am. Malacol. Bull. 5: 9-19.
Rollo, C. and M. Hawryluk. 1988. Compensatory scope and resource allocation in two species of aquatic snails. Ecology 69: 146-156.
Swanson, G., and M. Meyer. 1977. Impact of fluctuating water levels on feeding ecology of breeding blue-winged teal.  J. Wildl. Manage. 41: 426-433.
Terry, C.H. and T.F. Duda 2021.  Consequences of captive-rearing and exposure to cures from potential predators on shell sizes and shapes of North American stagnicoline gastropods (Family Lymnaeidae).  American Malacological Bulletin 38: 1 - 9.
Walter, H. 1969. Illustrated biomorphology of the "angulata" lake form of the basommatophoran snail Lymnaea catascopium Say. Malacological Review 2: 1-102.