Snails: Indian Ford Juga (Juga hemphilli subsp. nov.)
(Gastropoda: Neotaenioglossa: Semisulcospirinae) Profile prepared by Sarah Foltz Jordan, Sarina Jepsen and Julia Janicki, The Xerces Society for Invertebrate Conservation.
Juga is a genus of medium-sized, aquatic, gilled snails. Juga hemphilli subsp. nov. is a new (undescribed) subspecies with its nacre white and its shell dark brown with two dark brown bands. Juga snails are characterized as rasper-grazers, feeding on both algae and detritus, such as dead alder leaves. The habitat for this subspecies is considered to be streams and spring-seeps; it is known from the headwaters of the Columbia River in British Columbia, the Columbia River Gorge of Oregon and Washington, and the Deschutes River system in Oregon. Nutrient enhancement, grazing, water diversions and such activities that degrade the water quality are the major threats to Juga hemphilli. Further surveys should be done in order to evaluate better the current status of the species.
Juga hemphilli subsp. nov. is a new (undescribed) subspecies which somewhat resembles Juga (Juga) hemphilli maupinensis in its relatively large size (~25mm) (Frest & Johannes 1995). It is distinct from J. h. maupinensis in that the nacre is white (as opposed to light purple when fresh) and the shell is dark brown and with two dark brown bands (as opposed to a yellow-brown shell with one band) (Frest & Johannes 1995). Additionally, the juvenile is narrower than in J. h. maupinensis, the shell is more elongate, and there are several lirations (small raised ribs) on the mature whorls (Frest & Johannes 1995). It should be noted that this taxon is not the taxon described as Juga (Juga) hemphilli n. subsp. in Frest & Johannes (1993).
Egg mass: The Juga egg mass generally consists of thick finger-like, elongate, rather weakly coherent gelatinous aggregations, often several cm in length and 2-4 cm in width, with hundreds to thousands of moderately loosely packed, quite small (< 1 mm) eggs, with individual egg boundaries not very apparent, and without regular arrangement of eggs. The fresh egg mass deteriorates roughly a month after deposition, when the embryos begin to acquire shells and hatch (Frest & Johannes 2006). There is no veliger stage.
Federal Land: The subspecies is documented on the Deschutes National Forest (Frest & Johannes 1995).
Abundance: No abundance estimates have been made for this subspecies, but according to NatureServe (2009), Juga hemphilli is declining (10-30%).
Management: Manage new and known sites and their associated watersheds to reduce the impacts of water diversions, grazing, recreational activity and other practices that may adversely affect water quality.
Deixis MolluscDB database. 2009. An unpublished collection of mollusk records maintained by Ed Johannes.
Duncan, N. 2008. Survey Protocol for Aquatic Mollusk Species: Preliminary Inventory and Presence/Absence Sampling, Version 3.1. Portland, OR. Interagency Special Status/Sensitive Species Program. U.S. Department of Interior, Bureau of Land Management, Oregon/Washington and U.S. Department of Agriculture, Forest Service, Region 6. 52 pp.
Frest, T.J. and E.J. Johannes. 1993. Mollusk species of special concern within the range of the northern spotted owl. Final Report to Forest Ecosystem Management Working Group, USDA Forest Service. Deixis Consultants, Seattle, Washington. 98 pp.
Frest, T.J. and E.J. Johannes. 1995. Interior Columbia Basin mollusk species of special concern. Final report: Interior Columbia Basin Ecosystem Management Project, Walla Walla, WA. Contract #43-0E00-4-9112. 274 pp. plus appendices.
Frest, T.J. and E.J. Johannes. 2006. Draft. Review of the Status of Juga (Western U. S. Cerithioidea, Pleuroceridae, Semisulcospirinae). Unpublished document available from Ed Johannes.
Furnish, J.L. 1989. Factors affecting the growth production and distribution of the stream snail Juga silicula (Gould) [Doctoral Dissertation]: Department of Entomology, Oregon State University, 216 p.
Furnish, J.L. 1990. Factors affecting the growth, production and distribution of the stream snail Juga silicula (Gould). Unpublished PhD thesis, Oregon State University, 173 pp.
Johannes, Ed. 2009. Personal communication with Sarah Foltz Jordan, Xerces Society.
Lee, T., J.J. Kim, H.C. Hong, J.B. Burch, and D.O. Foighil. 2006. Crossing the continental divide: the Columbia drainage species, Juga hemphilli (Henderson, 1935) is a cryptic member of the eastern North American genus Elimia (Cerithioidea: Pleuroceridae). Journal of Molluscan Studies, 72: 314-317.
NatureServe. 2009. “Elimia hemphilli”. Version 7.1 (2 February 2009). Data last updated: October 2009. Available at: www.natureserve.org/explorer (Accessed 17 May 2010).
Strong, E. & F. KÃ¶hler. 2009. Morphological and molecular analysis of “Melania” jacqueti Dautzenberg & Fischer, 1906: from anonymous orphan to critical basal offshoot of the Semisulcospiridae (Gastropoda: Cerithioidea). Zoologica Scripta 38(5): 483-502. Available at: doi:10.1111/j.1463-6409.2008.00385.x (Accessed 17 May 2010).
Strong, E.E. and T.J. Frest. 2007. On the anatomy and systematics of Juga from western North America (Gastropoda: Cerithioidea: Pleuroceridae). The Nautilus 121(2): 43-65. Taylor, D.W. 1966. Summary of North American Blancan Nonmarine Mollusks. Malacologia 4:1-172.