''Discus macclintocki'' is a species of land snail in the family

Discidae Discidae is a taxonomic family of small air-breathing land snails, terrestrial gastropod mollusks in the superfamily Punctoidea. Genera The family Discidae has no subfamilies. Genera within the family Discidae include: * ''Anguispira'' Morse, ...

known commonly as the Iowa Pleistocene snail and Pleistocene disc. It occurs in

Iowa Iowa () is a state in the Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wisconsin to the northeast, Illinois to th ...

and

Illinois Illinois ( ) is a state in the Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolitan areas include, Peoria and Rockf ...

in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

.Frest, T. 2004
''Discus macclintocki''.
The IUCN Red List of Threatened Species 2004. Downloaded on 18 August 2017. It is a federally listed endangered species.Iowa Pleistocene Snail (''Discus macclintocki'').
Endangered Species. USFWS Midwest Region. 2013.

Biology

This snail is limited to patches of algific talus slope habitat. It is a

relict A relict is a surviving remnant of a natural phenomenon. Biology A relict (or relic) is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas. Geology and geomorphology In geology, a r ...

species from the last

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gre ...

. Much of its remaining habitat is located on the

Driftless Area National Wildlife Refuge Driftless Area National Wildlife Refuge is a United States National Wildlife Refuge in northeastern Iowa, southwestern Wisconsin and northwestern Illinois. It is a non-contiguous collection of parcels in the vicinity of the Upper Mississippi Ri ...

in Iowa. Known from fossil evidence about 400,000 years old, it is one of many glacial relict species that remain in the

Driftless Area The Driftless Area, a topographical and cultural region in the American Midwest, comprises southwestern Wisconsin, southeastern Minnesota, northeastern Iowa, and the extreme northwestern corner of Illinois. Never covered by ice during the las ...

, a

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...

-eroded plateau that now makes up parts of Iowa, Illinois,

Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...

, and

Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...

. Much of the area was covered by glaciers about 500,000 years ago, while parts of the Driftless Area were unglaciated. The algific talus slope habitat that harbors the snail is a landscape cooled by air and water emerging from masses of subterranean ice. The ground temperature rarely exceeds 50 °F even in summer. Here the snail feeds on

leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that have fallen to the ground. This detritus or dead organic material and its constituent ...

from trees (mainly birch, maple and dogwood) and shrubs. During the winter, it burrows underground and becomes dormant. It breeds from March to August, laying two to six eggs in the litter. Juveniles emerge in about 28 days. The life span of the snail is 5 to 7 years. The adult is about 5-8 millimeters wide,Driftless Area National Wildlife Refuge: Wildlife & Habitat.
USFWS. with a brownish or greenish shell.

Conservation status

The Iowa Pleistocene snail was thought to be extinct until it was discovered in 1955 by a scientist working in northeastern Iowa. It was listed as endangered by the United States in 1978. The main cause of the snail's decline is

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

, as it is restricted to patches of cold habitat in warmer surroundings. The snail is considered to be a relic of the ice age. About 75% of this snail’s original habitat has been destroyed since 1850. Other causes include loss of habitat to logging,

quarry A quarry is a type of open-pit mine in which dimension stone, rock, construction aggregate, riprap, sand, gravel, or slate is excavated from the ground. The operation of quarries is regulated in some jurisdictions to reduce their envir ...

ing,

livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animal ...

, pesticides, the construction of roads, and predation by

shrew Shrews (family Soricidae) are small mole-like mammals classified in the order Eulipotyphla. True shrews are not to be confused with treeshrews, otter shrews, elephant shrews, West Indies shrews, or marsupial shrews, which belong to differ ...

s.''Discus macclintocki''.
Status of Listed Species and Recovery Plan Development. USGS. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of nat ...

assessed the snail as a

species of least concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

for the

Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...

, because its populations are apparently stable and none were lost in the decade prior to the assessment.

Driftless Area National Wildlife Refuge

The Driftless Area National Wildlife Refuge was established in 1989 to protect native flora and fauna, including endangered and

threatened species Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of '' critical depen ...

such as the Iowa Pleistocene snail. The refuge conserves the algific talus slope habitat and other local habitat such as cold, moist

sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...

s. Other glacial relict snails occur on the refuge, including the Midwest Pleistocene vertigo (''Vertigo hubrichti''). Rare plants include the northern blue monkshood (''Aconitum noveboracense''), which thrives in the same cool talus habitat as the snail.

References

External links

Iowa Pleistocene snail (''Discus macclintocki'').
Environmental Conservation Online System. USFWS.

Biology

Conservation status

Driftless Area National Wildlife Refuge

References

External links

Further reading