Plants and Animals

Mesodon clausus Yellow globelet

Key Characteristics

The yellow globelet (Mesodon clausus, also called Helix clausus and Polygyra clausus) is a land snail with a finely ribbed yellow to yellowish-brown shell of about .5 inches in diameter. Additional features of the shell include 4-5 whorls, a relatively high, dome-shaped spire, and a smooth, round aperature lacking a parietal tooth. The granulated body is a brown to black with a lighter underside, with short tentacles and long tapering eye pedunlces.

Status and Rank

US Status:
State Status: SC - Special Concern (rare or uncertain; not legally protected)
Global Rank: G5 - Secure
State Rank: SNR - Not ranked

Occurrences

CountyNumber of OccurrencesYear Last Observed
Barry11939
Lenawee21939
Monroe2

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 yellow globelet has been found in forested river valleys, grasslands, shrubby successional habitats and railroad embankments (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

Identification and conservation of important habitat areas is an important first step toward land snail species management. Destruction of habitat through agricultural and residential development, as well as human disturbance, is considered the greatest threat to land snails, as they are incapable of widespread dispersal following such changes (Kay 1995). Moist microhabitats with uncompacted soil and a rich layer of organic litter are required by many species (Nekola 2003), including the yellow globelet. The loss of vegetative ground cover through mowing, intensive recreational use and heavy grazing may negatively affect this species. Wild and prescribed fire has a significant negative effect on land snail abundance and diversity (Applegarth 1999, Nekola 2002). Snag retention should be planned for, as large downed logs may provide important refuges during fire and drought (Applegarth 1999). Snails rapidly absorb and bioaccumulate chemical pollutants and heavy metals (Berger and Dallinger 1993, Regoli et al. 2006), and high exposure to heavy metals has been found to prevent reproduction (Notten et al. 2006). Herbicides and insecticides should be applied with caution and affected populations monitored to evaluate impacts.

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 first week of October

Time of Day: Daytime

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.
  • 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. 2002. Effects of fire management on the richness and abundance of central North American grassland land snail faunas. Animal Biodiversity and Conservation 25(2):53-66.
  • 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.