Pristiloma pilsbryi
Crowned tightcoil
Survey recommendations for the species in Washington state
Compiled for the Interagency Special Status Sensitive Species Program
By Candace Fallon, the Xerces Society for Invertebrate Conservation
Reviewed by Rob Huff, Interagency Special Status Sensitive Species Program, and
John Fleckenstein, Washington Natural Heritage Program
January 2015
Introduction
The crowned tightcoil, Pristiloma pilsbryi, is a small terrestrial snail endemic to the Pacific Northwest. It
is a Forest Service and BLM sensitive species in Oregon and strategic species in Washington. Xerces
Society staff gathered all known records of this species in Washington State, mapped them, and
determined their proximity lands managed by the US Forest Service or Bureau of Land Management.
The goal of this exercise was to determine if P. pilsbryi is likely to occur on Forest Service or BLM land in
Washington, and if so, to make recommendations for future surveys.
Conservation Status
Global status: G1 (last reviewed 8 Oct 2002)
Rounded global status: G1 – Critically imperiled
National Status (U.S.): N1 – Critically imperiled (last reviewed 8 Oct 2002)
State Status: S1 (OR and WA) – Critically imperiled
IUCN Red List: NE – Not evaluated
Methods
In November and December 2014, Xerces staff gathered all available records of Pristiloma pilsbryi in
Washington and Oregon. We consulted the following curators, collections databases, and mollusk
experts to gather these records:







Academy of Natural Sciences Malacology Collection online database
Barry Roth (mollusk expert)
California Academy of Sciences Invertebrate Zoology Collection online database
Casey Richart (PhD candidate at San Diego State University) (no reply)
Chris Marshall (Oregon State Arthropod Collection)
Darci Rivers-Pankratz (USFS)
Ed Johannes (Deixis Consultants)












Elizabeth Nesbitt (Burke Museum Mollusk Collection)
Global Biodiversity Information Facility (GBIF)
Harvard Museum of Comparative Zoology online database
Illinois Natural History Survey online database
John Fleckenstein (Washington Natural Heritage Program)
Mark Siddall (American Museum of Natural History Mollusk Collection)
Santa Barbara Museum of Natural History Invertebrate Zoology Collection online database
Smithsonian National Museum of Natural History online database
Tiffany Young (USFS)
Tim Pearce (Carnegie Museum of Natural History Collections)
Tom Burke (mollusk expert)
Taehwan Lee (University of Michigan Museum of Zoology)
All records were added to an Excel file and any records that did not have geographic coordinates were
georeferenced and assigned an accuracy code, then mapped in ArcMap. We then overlaid a shapefile of
Forest Service and BLM managed lands in Oregon and Washington to determine the proximity of these
records to federal lands (see Fig. 1).
Results and Discussion
Few historic records exist for the crowned tightcoil; however it is suspected that the historic range of
this species probably echoed that of the closely related Pristiloma stearnsi, which ranged from southern
Alaska to southern Oregon west of the Cascades (Frest & Johannes 2000, Stone & Huff 2010). P. pilsbryi
appears to be coastal-associated, with documented occurrences in Pacific, Wahkiakum, Clallam, and
Tillamook Counties, as well as a record from Multnomah County, OR (see Appendix). Current
distribution is uncertain. In Washington, only five or so new records have been established in the last 20
years.
Baker (1931) describes the crowned tightcoil as being associated with old growth and riparian habitat,
most abundant under dense thickets of salal near the coast; however, Frest and Johannes (2000) did not
find salal to be very common at the sites where they encountered this species. In general, P. pilsbryi is
found in very moist forests, including floodplains, in decaying leaf litter, commonly found under dense
salal or vine maple, waterleaf, or other deciduous vegetation (Baker 1931, Frest & Johannes 2000).
Records from Washington State are not known from or adjacent to BLM or Forest Service land, with the
potential exception of one record from Clallam County. The closest federal lands to known occurrences
are the Olympic National Forest, the Gifford Pinchot National Forest, and the Columbia River Gorge
National Scenic Area. The latter two list this species as suspected (Stone & Huff 2010, ISSSSP 2014). It is
also suspected in Grays Harbor, Cowlitz, and Clark Counties (Frest & Johannes 2000).
Past survey efforts for P. pilsbryi in the Pacific Northwest have occurred in the Oregon Cascades and
Coast Range (Branson & Branson 1984), the Washington Cascades and Olympics (Branson 1977, 1980),
and the Long Beach Peninsula (Frest & Johannes 2000), all of which failed to find this species. The
Olympic surveys (Branson 1977) alone covered 122 sites. Recent surveys have been more successful;
Frest and Johannes (2000) found this species in Clallam and Pacific Counties, and Richart made several
collections in Tillamook, Clatsop, and Pacific Counties between 2004 and 2006.
Figure 1. Known and unconfirmed records and suspected distribution of crowned tightcoil (Pristiloma pilsbryi) in Oregon and
Washington (all records dating back to 1929). Note that all records have varying levels of coordinate accuracy depending on
the data source, and some (such as the unconfirmed Clallam locality) are only mapped to the county centroid.
Local mollusk experts know of few other survey efforts or recent records in Washington. Barry Roth
(2014, pers. comm.) does not have any records for this species in his database, nor is he aware of any
survey efforts or other records. Ed Johannes (2014, pers. comm.) does not have any additional
information on this species either. He has not surveyed for it since 1992 nor has he heard of any surveys
conducted for it recently. Tom Burke (2014, pers. comm.) has not collected this species himself but he
has identified several collections for others, including a Pacific County collection he identified for the
Olympic National Forest. As there is no Forest Service land in Pacific County, Burke believes this
collection must have been from a DNR plot.
Recommendations
There is little old growth and very little mature forest remaining in southwest Washington, and large
stands of coastal salal and coastal forests are rare (Stone & Huff 2010). In addition, the Forest Service
and BLM do not manage any lands in this region except on the Olympic Peninsula, from which only one
(vague) record is known. Appropriate habitat may exist further inland in the Gifford Pinchot National
Forest or Columbia River Gorge National Scenic Area, but no documented occurrences of this species
have been made in that area to date. It is very possible that P. pilsbryi has been overlooked in past
surveys due to its tiny size (3.4 mm) and the fact that it is usually found deep within a substrate of
decaying leaves and forest debris. Additional, targeted surveys for this species are recommended in
appropriate habitat on the Olympic National Forest. In addition, future general mollusk surveys on the
Olympic NF as well as the Gifford Pinchot NF and Columbia River Gorge NSA should include P. pilsbryi as
a potential target species so that surveyors are aware of it and search appropriate habitat in those
areas.
Prior to surveys, an effort should be made to seek out additional information regarding the one
unconfirmed Clallam County record (Frest & Johannes 2000) to see if this is a valid collection and, if so,
to gather habitat and land ownership data. At the time of this report, Xerces staff members were unable
to track down any additional information on this collection. Surveyors should also be aware that Casey
Richart, a PhD student at San Diego State University, has made several collections of P. pilsbryi in recent
years and is currently in the process of publishing his findings, which may shed more light on this species
in Washington (Pearce 2014, pers. comm.). We include several of Richart’s collections in the Appendix;
however, Xerces staff members were unable to get in touch with Richart directly for this project, and it
is possible he has other records for this species in Washington.
References
Baker, H.B. 1931. Nearctic vitreine land snails. Proceedings, Academy of Natural Sciences of Philadelphia
73: 85-117.
Branson, B.A. 1977. Freshwater and terrestrial Mollusca of the Olympic Peninsula, Washington. The
Veliger 19: 310-330.
Branson, B.A. 1980. Collections of gastropods from the Cascade Mountains of Washington. The Veliger
23: 171-176.
Branson, B.A. and M.L. Branson. 1984. Distributional records for terrestrial and freshwater Mollusca of
the Cascade and Coast Ranges, Oregon. The Veliger 26: 248-257.
Burke, T. 2013. Land Snails and Slugs of the Pacific Northwest. Oregon State University Press, Corvallis,
OR. 344 pp.
Burke, T. 2014. Personal communication with Candace Fallon.
Fleckenstein, 2014. Personal communication with Candace Fallon.
Frest, T.J. and E.J. Johannes. 2000. A baseline mollusk survey of southwestern Oregon, with emphasis on
the Rogue and Umpqua River Drainages. Deixis Consultants, Seattle, Washington. Prepared for Oregon
Natural Heritage Program, Portland, Oregon.
[ISSSSP] US Forest Service / Bureau of Land Management. 2014. Interagency Special Status / Sensitive
Species Program Strategic Species Lists. Available at http://www.fs.fed.us/r6/sfpnw/issssp/agencypolicy/ (last accessed 23 December 2014).
Johannes, E. 2014. Personal communication with Candace Fallon.
Pearce, T. 2014. Personal communication with Candace Fallon.
Roth, Barry. 2014. Personal communication with Candace Fallon.
Stone, T and R. Huff. 2010. Species fact sheet: Crowned tightcoil, Pristiloma pilsbryi (Vanatta, 1899).
USDA Forest Service and USDOI Bureau of Land Management, Washington and Oregon.
Appendix: Known records for P. pilsbryi in Oregon and Washington
UTM_N
UTM_E
Datum
Zone
Loc
Acc
Land
Owner
Clatsop
State
Forest
5113715.6
459291.7
NAD83
10
GPS3
5041152.9
525286.6
NAD83
10
MAN6
5012385.0
458848.0
NAD27
10
GPS3
5008265.4
434156.6
NAD83
10
GPS3
5321773.6
430593.7
WGS84
10
VAGUE
Adjacent
Federal
CRGNSA
SAL
SIU
State
County
Location
OR
Clatsop
Ziak-Gnat Cr
Ln jct US30,
Clatsop State
Forest
8-Feb-04
OR
Multnomah
Portland, OR
UNK
Type
specimen.
OR
Tillamook
Haag Pass
12-Dec04
Adult shell
OR
Tillamook
Hebo, Forest
Rd 14, 2.2 mi
NE of SR22
10-Dec05
WA
Clallam
5146492.4
437435.9
NAD83
10
MAN2
WA
Pacific
A 3300 Road,
WDFW Type
N Basin
3576, Middle
Nemah R
5137807.8
431979.3
WGS84
10
MAN6
WA
Pacific
Ellsworth
Creek
5133734.5
418880.7
NAD83
10
MAN6
WA
Pacific
Long Beach
Date
Notes
Juvenile
animal
1997?
Adult animal
Unconfirmed
record from
Frest &
Johannes
2000.
7-Jun-06
Adult animal
1929
Count: 6.
UTM_N
UTM_E
Datum
Zone
5133734.5
418880.7
NAD83
10
5131478.8
438408.9
NAD83
10
Loc
Acc
MAN6
MAN4
Land
Owner
Adjacent
Federal
State
County
Location
WA
Pacific
Long Beach
Pacific
Naselle
(3.5mi S), Rt
401, Cement
Cr (near)
WA
5121301.5
432507.5
WGS84
10
VAGUE
WA
Pacific
Near the
Astoria
Bridge
5121436.5
432639.5
NAD83
10
MAN5
WA
Pacific
Point Ellis
Pacific
Raymond (6
horiz mi S),
WDFW Type
N Basin
3111, Willapa
R (S Fk)
Site Split B,
G4 [DNR
plot]
5158836.9
444451.9
NAD83
10
MAN2
WA
5155708.8
445982.7
WGS84
10
VAGUE
WA
Pacific
5126769.9
467099.6
WGS84
10
VAGUE
WA
Wahkiakum
Date
Notes
15-Jan06
From Tom: Bill
Leonard says
Casey Richart
has a record
from this area.
1929
Count: 3.
15-Jul-06
2 adult, 3
juvenile
16-Dec02
Tom says he
identified this
for the
Olympic NF.
From Tom: Bill
Leonard says
Casey Richart
has a record
from this area.