Gonidea

Gonidea angulata, the western ridged mussel or Rocky Mountain ridged mussel, is a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels. It is the only species in the genus Gonidea.

Gonidea
Mature western ridged mussel
Conservation status
Vulnerable  (NatureServe)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Bivalvia
Order:	Unionida
Family:	Unionidae
Genus:	Gonidea Conrad, 1857
Species:	G. angulata
Binomial name
Gonidea angulata (Lea, 1838)[2]

Description

Shell is 125 mm long, 65 mm high, 40 mm wide.^[3]

Distribution

The western ridged mussel historically occurred in river basins spanning portions of the western states of California, Idaho, Nevada, Oregon, and Washington, and the Canadian province of British Columbia.

Conservation status

The western ridged mussel has declined significantly throughout much of its range in western North America. Research indicates that the species has experienced a significant reduction in range from the historic distribution (43%),^[4] with the southern extent of the species’ range in California having contracted northward approximately 475 miles as compared to the historic range. Live western ridged mussels were not detected at 46% of the 87 sites where it historically occurred and that have been recently revisited.

In Canada, it lives in British Columbia, where the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has listed it as a species of special concern. The Canadian Species at Risk Act listed it in the List of Wildlife Species at Risk as being a species of special concern in Canada in 2003, and as endangered in 2010.^[5][6]

References

1. "Gonidea angulata". NatureServe. Retrieved 2016-07-08.
2. Lea, I. 1838. Description of new freshwater and land shells. American Philosophical Society, Transactions 6: 1-111.
3. COSEWIC 2003. COSEWIC assessment and status report on the Rocky mountain ridged mussel Gonidea angulata in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 29 pp. (www.sararegistry.gc.ca/status/status_e.cfm) http://www.sararegistry.gc.ca/virtual_sara/files/cosewic/sr_rocky_mount_ridged_mussel_e.pdf
4. Blevins, E., S. Jepsen, J. Brim Box, D. Nez, J. Howard, A. Maine, and C. O’Brien. 2017a. Extinction risk of western North American freshwater mussels: Anodonta nuttalliana, the Anodonta oregonensis/kennerlyi clade, Gonidea angulata, and Margaritifera falcata. Freshwater Mollusk Biology and Conservation 20:71–88.
5. COSEWIC. 2005. Canadian Species at Risk. Committee on the Status of Endangered Wildlife in Canada. 64 pp., page 27.
6. COSEWIC. 2011. Archived 2011-09-30 at the Wayback Machine. COSEWIC, Committee on the Status of Endangered Wildlife in Canada