Plants and Animals

Mesodon mitchellianus Sealed globelet

Key Characteristics

The polished, thin and yellowish shell of the sealed globelet (Mesodon mitchellianus, also Polygyra mitchellianus and Helix mitchellianus) is up to .6 inches in diameter with 5 finely striated whorls and a globose-cone shape. The aperature is smooth and round. The body of this species is large in comparison to its shell and coarsely granulated, with the short tentacles and long tapering eye peduncles being slightly darker in color than the rest of the body.

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
Macomb1

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

This species most commonly occurs in meadows, roadsides and floodplains, emerging from beneath organic litter when the ground is wet (Hubricht 1985).

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

The first step in managing for this species is to gain a better understanding of its current population, distribution, and habitat requirements. Being small and primarily sessile creatures, land snails depend on suitable microhabitat conditions, which in turn depend on large-scale landscape factors. Moist and sheltered areas suitable for many species of land snail may be preserved by maintaining forest canopy and vegetative ground cover, reducing heavy recreational traffic and grazing, and preventing an increase in edge area (Applegarth 1999, Gotmark et al. 2008, Suominen 1999, Walden 1995). High intensity fire can harm land snails through direct mortality and reduction of ground vegetation, woody debris and leaf litter. Retention of snags may provide important shelter during times of extreme heat and drought (Applegarth 1999). Herbicide and insecticide spraying pose a threat to gastropods, as they rapidly bioaccumulate chemicals and heavy metals (Berger and Dallinger 1993) Species that make use of roadside habitats, such as the sealed gobelet, may be impacted by road salt (Nekola 2009) and pollution from vehicular traffic (Regoli et al. 2006).

Active Period

Breeding from first week of May to fourth week of June

Survey Methods

In wet conditions, this species can be found visually. As it often hides among organic litter layers, specimens can also be 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 first week of October

Time of Day: Daytime

Visual in suitable habitat

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

Time of Day: Daytime
Precipitation: Just after rain

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.
  • Hubricht, L. 1985. The Distributions of Native Land Mollusks of the Eastern US. Field Museum of Natural History. Fieldiana: Zoology, No. 24.
  • Nekola, J.C. 2009. Conservation Prioritization of the Ontario and Quebec Land Snail Faunas. Final Report Submitted to: Committee on the Status of Endangered Wildlife in Canada (COSEWIC). 120 pp.
  • 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.
  • Suominen, O. 1999. Impact of cervid browsing and grazing on the terrestrial gastropod fauna in the boreal forests of Fennoscandia. Ecography 22:651-58.
  • 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.