Plants and Animals

Mesodon pennsylvanicus Proud globelet

Key Characteristics

The proud globelet (Mesodon pennsylvanicus, also Helix pennsylvanica and Polygyra pennsylvania) is characterized by a yellowish, globose shell of about .8 inches in diameter with a high spire and 6 obliquely striated whorls. The body is coarsely granulated, of a dark gray color above and lighter below.

Status and Rank

US Status:
State Status: SC - Special Concern (rare or uncertain; not legally protected)
Global Rank: G4 - Apparently secure
State Rank: SNR - Not ranked

Occurrences

CountyNumber of OccurrencesYear Last Observed
Monroe4
Wayne2

Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.

Habitat

The proud globelet is typically found in heavily wooded ravines (Baker 1939).

For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Management Recommendations

Habitat loss, fragmentation and degradation are considered the greatest threats to land snail species (Kay 1995). Depending mainly on moist microhabitats with a thick organic litter layer and rich, uncompacted soil (Nekola 2003), forest dwelling snails may be negatively affected by increased edge area, forest canopy reductions, and the loss of vegetative ground cover, as microhabitat characteristics will be altered (Applegarth 1999, Gotmark et al. 2008, Walden 1995). Fire can negatively affect land snail populations and microhabitats. Large downed logs may provide important refuges during periods of fire and drought, and should be retained (Applegarth 1999). Locating important proud globelet habitat areas will be an important first step toward protecting this species. Snails bioaccumulate chemical pollutants and heavy metals (Berger and Dallinger 1993, Regoli et al. 2006), and high exposure has been found to prevent reproduction (Notten et al. 2006). Where vulnerable gastropods may be present, herbicides and insecticides should be applied with caution and affected populations monitored.     

Active Period

Breeding from first week of May to fourth week of June

Survey Methods

As visual detection of this species is difficult, specimens are collected by litter sampling in suitable habitat. Samples are thoroughly heat-dried, soaked in water for a number of hours to separate the various components, and finally passed through a series of sieves. The shells are then able to be hand-picked from the remaining sample material (Nekola 2003).

Litter sampling

Survey Period: From first week of April to fourth week of October

References

Survey References

  • Nekola, J.C. 2003. Large-scale terrestrial gastropod community composition patterns in the Great Lakes region of North America. Diversity and Distributions 9:55-71.

Technical References

  • Applegarth, J.S. 1999. Management recommendations for terrestrial mollusk species, Megophix hemphilli, the Oregon Megomphix. Version 2.0. 39pp.
  • Baker, F.C. 1939. Fieldbook of Illinois Land Snails. Illinois Natural History Survey Manual 2, Urbana, Illinois. 166pp.
  • Berger, B. and R. Dallinger. 1993. Terrestrial snails as quantitative indicators of environmental metal pollution. Environmental Monitoring and Assessment 25(1):65-84.
  • Gotmark, F., T. Von Proschwitz, and N. Franc. 2008. Are small sedentary species affected by habitat fragmentation? Local vs. landscape factors predicting species richness and composition of land molluscs in Swedish conservation forests. Journal of Biogeography 35: 1062-76.
  • Kay, E.A. 1995. Hug a slug, save a snail: A status report on molluscan diversity and a framework for conservation action. Pp. 53-79. In: E.A. Kay (ed). 1995. The Conservation Biology of Molluscs. IUCN, Gland, Switzerland.
  • Nekola, J.C. 2003. Large-scale terrestrial gastropod community composition patterns in the Great Lakes region of North America. Diversity and Distributions 9:55-71.
  • Notten, M.J.M., A.J.P. Oosthoek, J. Rozema, and R. Aerts. 2006. Heavy metal pollution affects consumption and reproduction of the landsnail Cepaea nemoralis fed on naturally polluted Urtica dioica leaves. Ecotoxicology 15(3):295-304.
  • Regoli, F., S. Gorbi, D. Fattorini, S. Tedesco, A. Notti, N. Machella, R. Bocchetti, M. Benedetti, and F. Piva. 2006. Use of the Land Snail Helix aspersa as Sentinel Organism for Monitoring Ecotoxicologic Effects of Urban Pollution: An Integrated Approach. Environmental Health Perspectives 114(1):63-69.
  • Walden, H.W. 1995. Endangered species of land molluscs in Sweden and Madeira. In: The IUCN Species Survivial Commission, The Conservation Biology of Molluscs:19-24 (E. Alison Kay, Ed.) International Union for Conservation of Nature and Natural Resources, Gland, Switzerland.
  • Walker, B. 1905. An Illustrated Catalogue of the Mollusca of Michigan. Report of the State Board of Geological Survey of Michigan for the Year 1905.