''Deroceras hesperium'',
common name
In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...
the evening fieldslug, is a
species of air-breathing land
slug
Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a smal ...
, a
terrestrial pulmonate
Pulmonata or pulmonates, is an informal group (previously an order, and before that a subclass) of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. The group includ ...
gastropod
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda ().
This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...
mollusk in the family
Agriolimacidae.
Distribution
''Deroceras hesperium'' was described by
Henry A. Pilsbry
Henry Augustus Pilsbry (7 December 1862 – 26 October 1957) was an American biologist, malacologist and carcinologist, among other areas of study. He was a dominant presence in many fields of invertebrate taxonomy for the better part of a cent ...
from slugs collected at Oswego,
Oregon.
Later (1948), Pilsbry elaborated on the
type locality and stated it as "a small island in
Oswego Lake, Oswego,
Clackamas County
Clackamas County is one of the 36 counties in the U.S. state of Oregon. As of the 2020 census, the population was 421,401, making it Oregon's third-most populous county. Its county seat is Oregon City. The county was named after the Native ...
,
Oregon.
In the same publication, he added additional Oregon records and mentioned a collection of slugs found in 1887 from
Comox,
Vancouver Island,
British Columbia.
Conservation Status
This species was assessed as "
Data Deficient
A data deficient (DD) species is one which has been categorized by the International Union for Conservation of Nature (IUCN) as offering insufficient information for a proper assessment of conservation status to be made. This does not necessaril ...
" (DD) by the
Committee on the Status of Endangered Wildlife in Canada
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC, French: Comité sur la situation des espèces en péril au Canada, COSEPAC) is an independent committee of wildlife experts and scientists whose "raison d'être is to identify s ...
(COSEWIC).
[COSEWIC. 2005]
Canadian Species at Risk
Committee on the Status of Endangered Wildlife in Canada. 64 pp., page 38. In the Northwestern US, this formerly common species has declined by 50-75% and is now "truly rare" according to the 2004 Survey and Manage species assessment. It is now found only in northwestern Oregon, the northern Olympic Peninsula and the northeast coast of Vancouver Island. The US Fish and Wildlife Service recently determined that listing this species as endangered may be warranted due to the present or threatened destruction of its habitat resulting from activities that lower the water table or reduce soil moisture, including spring diversions, grazing, and logging.
References
Agriolimacidae
{{Agriolimacidae-stub