PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
Psilochorus hesperus (Northwestern Cellar Spider) is a cellar spider (Family Pholcidae) characterized by specialized copulatory structures, basally fused jaws and six of their eyes arranged in a pair of distinctive triads. The species has long and spindly legs, a small body size, Y-shaped groove on the head, distinctive spurs on the male jaws and bovine-udder-like female genitalia. This spider has limited dispersal abilities.
Cellar spiders derive their name from the human structures in which some of the species in this family are commonly found: undisturbed dark crevices within buildings, homes, basements and cellars. However, only a fraction of the 1350 named species occur within anthropogenic habitats. Most species live in natural habitats that include caves, under rocks and in abandoned mammal burrows. Psilochorus hesperus has not been found in basements or cellars.
Under Canada’s Species at Risk Act (SARA), the foremost function of COSEWIC is to "assess the status of each wildlife species considered by COSEWIC to be at risk and, as part of the assessment, identify existing and potential threats to the species".
COSEWIC held two Wildlife Species Assessment Meetings in this reporting year (October, 2013 to September, 2014) from November 24 to November 29, 2013 and from April 27 to May 2, 2014. During the current reporting period, COSEWIC assessed the status or reviewed the classification of 56 wildlife species.
The wildlife species assessment results for the 2012-2013 reporting period include the following:
Special Concern: 20
Data Deficient: 0
Not at Risk: 1
Of the 56 wildlife species examined, COSEWIC reviewed the classification of 40 that had been previously assessed. The review of classification for 25 of those wildlife species resulted in a confirmation of the same status as the previous assessment.