(DRAFT) - Taxonomy
Species SNAIL, NOONDAY
Species Id ESIS354003
Date 13 MAR 96
TAXONOMY
NAME - SNAIL, NOONDAY
OTHER COMMON NAMES - SNAIL and NOONDAY
ELEMENT CODE -
CATEGORY - Aquatic Molluscs
PHYLUM AND SUBPHYLUM - MOLLUSCA,
CLASS AND SUBCLASS - GASTROPODA,
ORDER AND SUBORDER - STYLOMMATOPHORA,
FAMILY AND SUBFAMILY - POLYGYRIDAE,
GENUS AND SUBGENUS - MESODON,
SPECIES AND SSP - CLARKI, NANTAHALA
SCIENTIFIC NAME - MESODON CLARKI NANTAHALA
AUTHORITY -
TAXONOMY REFERENCES -
COMMENTS ON TAXONOMY -
Noonday Snail
Mesodon clarki nantahala (Clench and Banks, 1932)
KINGDOM: Animal GROUP: Snail
PHYLUM: Mollusca CLASS: Gastropoda
ORDER: Stylommatophora FAMILY: Polygyridae
Mesodon clarki nantahala has a subglobose, imperforate shell of
about 5 1/2 whorls. It measures 17-18 mm in width and about 11 mm in
height. The shell is reddish and quite shiny when fresh. The lip of
the aperature is sharply reflected and the peristome is white. The
peristome of the basal area of the aperature is thickened to form an
almost blade-like tooth. The parietal wall has a long recurved tooth
(01,02,03). The surface of the shell is sculptured with rather coarse
striae that appear on the embryonic whorl as well.
Clench and Banks (01) named this taxon Polygyra (Triodopsis)
nantahala. Pilsbry (02) later relegated it to a subspecies of Mesodon
clarki. Hubricht (04) implies it is a fairly widespread ecological
variant of Mesodon clarki. Emberton (05), after studying shell
characters, reproductive morphology and electrophoretic data as part
of his thesis on the large polygyrids, leans toward its status as a
separate full species. John Fridell has recently (07) found greater
Taxonomy - 1 (DRAFT) - Taxonomy
Species SNAIL, NOONDAY
Species Id ESIS354003
Date 13 MAR 96
variation within the gorge populations than had been known. These
snails are being evaluated. The noonday snail may be only part of a
species cluster in and around the Nantahala Gorge (03,05,07).
The type specimen (#86429) is housed in the collection of the
Museum of Comparative Zoology, Harvard University. Paratypes were
deposited at the Philadelphia Academy of Natural Sciences, the
University of Michigan (02), and a private collection (07).
Photographs or drawings occur with the original description (01), in
Pilsbry (02), in Parker and Dixon (08), and in the recovery plan (03).
Taxonomy - 2 (DRAFT) - Status
Species SNAIL, NOONDAY
Species Id ESIS354003
Date 13 MAR 96
STATUS
Coded Status
North Carolina; State Listed
Tennessee; State Recognized
T: Federal Threatened
COMMENTS ON STATUS -
U.S. STATUSES AND LAWS:
The noonday snail (Mesodon clarki nantahala) has been designated
a Threatened species pursuant to the Endangered Species Act of 1973
(50 CFR 17.11; P.L. 93-205, 87 Stat. 884; 16 U.S.C. 1531-1540),
as amended. The subspecies has this status wherever found including
the States of North Carolina and Tennessee.
This subspecies is protected by the Lacey Act (P.L. 97-79, as
amended; 16 U.S.C. 3371 et seq.) which makes it unlawful to import,
export, transport, sell, receive, acquire, or purchase any wild
animal (alive or dead including parts, products, eggs, or offspring):
(1) in interstate or foreign commerce if taken, possessed,
transported or sold in violation of any State law or
regulation; or
(2) if taken or possessed in violation of any U.S. law,
treaty, or regulation or in violation of Indian tribal law.
It is also unlawful to possess any wild animal (alive or dead
including parts, products, eggs, and offspring) within the U.S.
territorial or special maritime jurisdiction (as defined in
18 U.S.C. 7) that is taken, possessed, transported, or sold in
violation of any State law or regulation, foreign law, or Indian
tribal law.
RESPONSIBLE FEDERAL AGENCIES:
USFWS -Responsible for the management/recovery, listing, and
law enforcement/protection of this species.
USFS -Responsible for the law enforcement/protection of this
species with applicable State and Federal laws on
public lands under their control. Also responsible
for management/recovery on Forest Service lands. The
Forest Service is responsible for integrating
management, protection, and conservation of Federally
listed species into the Forest Planning process
(36 CFR 219.19 and 219.20).
All Federal agencies have responsibility to ensure that any
action authorized, funded, or carried out by that agency is not likely
to jeopardize the continued existence of the species or result in the
destruction or adverse modification of Critical Habitat (50 CFR 402),
and to utilize their authorities to carry out programs for the
conservation of the species.
Status - 1 (DRAFT) - Status
Species SNAIL, NOONDAY
Species Id ESIS354003
Date 13 MAR 96
STATE STATUSES AND LAWS:
STATE: North Carolina
DESIGNATED STATUS: Threatened
ADMINISTRATIVE AGENCY: Wildlife Resources Commission
STATE STATUTES: NC Administrative Code, Wildlife resources and
Water Safety, Subchapter 101 - Endangered and
Threatened Species.
STATE: Tennessee
DESIGNATED STATUS: Recognized Threatened
ADMINISTRATIVE AGENCY: Wildlife Resources Agency
STATE STATUTES: TN Annotated Code, Chapter 9, Sec. 51-901
through 51-912.
INTERNATIONAL STATUSES, TREATIES, AND AGREEMENTS:
None.
ECONOMIC STATUSES:
The species does not have any cultural or commercial
significance. However, it is a unique species restricted to a very
limited range, and it has value for aesthetic and scientific reasons.
76/04/28:41 FR 17742/17747 - Proposed rule
78/07/03:43 FR 28932/ - Final rule, listed as Threatened
83/12/08:48 FR 55100/ - Five year review
Status - 2 HABITAT ASSOCIATIONS
HABITAT - TERRESTRIAL
TERRESTRIAL
LAND USE -
Transportation, communications, and Util
Deciduous Forest Land
Mixed Forest Land
COMMENTS ON HABITAT ASSOCIATIONS -
Mesodon clarki nantahala has been reported from specific areas
within the Nantahala Gorge. The gorge lies at the southern end of the
Appalachian Mountains where the Nantahala River cuts between Cheoah
Bald and Wesser Bald in the Nantahala Mountains (03). In general, the
region is dominated by oak-hickory forest; but in coves and other very
mesic areas, the oak-hickory forest tends to be replaced by mixed
mesophytic elements with rich herbaceous undergrowth (12,03). The
cliffs along the southeastern side of the gorge are a very special
example of this replacement (12). The gorge for nearly six miles is
fairly narrow with steep cliffs on either side. The Nantahala River,
the Southern Railroad (to the northwest), and U.S. Route 19 (to the
southeast) are jammed between the cliffs. The cliffs begin at the
level of the road and rise from 1900 feet to over 3000 feet in only
one-half mile. They are very moist, interrupted frequently by small
streams and waterfalls emiting from caves or springs. The cliffs are
heavily forested and because of their aspect are most often shaded.
The forest floor often has a thick humus layer and there is much
exposed rock. Some of the rock is limestone because of an incursion
of Murphy Marble (11).
The noonday snail occurs along the northwest facing cliffs for a
few miles up and down the river from Blowing Springs. It was reported
from Handpole Branch on the northwest side of the river, Graham Co.,
NC (13) but the small Mesodon that occurs there may be an as yet
undescribed species. The snails probably live among the rocks but
during rainy weather are found on vegetation all along the cliffs,
even at the roadside (03).
Exposed rock that provides shelter and produces rich soil, a
complex association of plants providing deep shade, and the moist
conditions may be unique to this area and account for the noonday
snail's limited distribution (03).
Habitat Associations - 1 (DRAFT) - Food Habits
Species SNAIL, NOONDAY
Species Id ESIS354003
Date 13 MAR 96
FOOD HABITS
TROPHIC LEVEL -
HERBIVORE
LIFESTAGE FOOD FOOD PART
General Detritus
General Deciduous Shrubs-Leaves/Twigs
General Myxomycophyta
General Forb Leaves/Stems
Food Habits - 1 (DRAFT) - Environment Associations
Species SNAIL, NOONDAY
Species Id ESIS354003
Date 13 MAR 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
G
G Aquatic Features: Springs [flowing]
G Terrestrial Features: Caves, wet
G Terrestrial Features: Cliffs/ledges
G Terrestrial Features: Rock outcrops
Environment Associations - 1 (DRAFT) - Life History
Species SNAIL, NOONDAY
Species Id ESIS354003
Date 13 MAR 96
LIFE HISTORY
FOOD HABITS:
Little is known about the snail's food preferences or feeding
behavior. The snails (adults and juveniles) were found actively
foraging(?) in early spring on a variety of herbs ranging from
stonecrop to Japanese honeysuckle (03). Other species of Mesodon are
believed to eat mainly fungal mycelia (02); but many have been
documented ingesting leaves of plants and rotted wood (14). The
snails are active during wet weather and may be on the surface of the
ground only when the weather is mild and rainy. The snail is thought
to estivate in dry weather and become dormant during the fall and
winter. So for many months of the year the noonday snail is not
eating anything (03).
HOME RANGE/TERRITORY:
The noonday snail is not known to be territorial. The snails
were found pretty much throughout the cliff area from the roadside to
the crest. The distribution seemed clumped though: several snails
would lie close together then none would occur for a few square meters
in either direction. They are not found in the streams, but need
moist conditions (or air with extremely high humidity). Under adverse
conditions, the snails are almost impossible to find. Obviously they
retreat into the numerous crannies and crevices within the cliff
itself (03).
PERIODICITY:
When the noonday snail has been found, no differences were noted
between the activity periods of the adults and juveniles. Some snails
were active during the day; some were active at night. Most of the
time all snails appeared quiescent or clamped down "sealed" to a
surface. during much of the year, the snails are not on the rock
surface or in the vegetation, but presumably are deep within the
cliff. Searches in two consecutive fall seasons have turned up very
few live animals (only juveniles) (16). During the on-site
investigation and spring 1984, the snails were relatively common on
the surface (03,07).
MIGRATION PATTERNS:
The only migration the noonday snail exhibits is from the surface
of the gorge cliffs to the many cavities within the cliff itself. It
is not known if this occurs daily; but there is certainly a seasonal
migration (03).
COVER/SHELTER REQUIREMENTS:
The noonday snail is only found in those parts of the gorge where
there is mature forest and sufficient moisture to provide deep shade
and mild temperatures. Apparently they occur only on the steep cliffs
where there is much exposed rock. During mild wet weather the snails
are found under rocks or cruising on a variety of herbs. In dry, very
warm or very cold weather, the snails retreat into the cliffs (03,07).
REPRODUCTIVE SITE REQUIREMENTS:
Life History - 1 (DRAFT) - Life History
Species SNAIL, NOONDAY
Species Id ESIS354003
Date 13 MAR 96
Nothing is known about reproductive site requirements for the
noonday snail. Breeding has never been observed and egg clutches have
never been found (03).
REPRODUCTIVE CHARACTERISTICS:
Little is known of the noonday snail's reproduction. However
certain characteristics are widespread among land snails (15). Most
land snails are hermaphrodites having both male and female
reproductive tracts within a single body. Self-fertilization is rare:
the snails "prefer" to copulate (with exchange of some type of
spermatophore) reciprocally. Copulation is commonly preceded by some
type of courtship display including trailing possible mates and
nipping about the head and neck (14). Fertilization does occur
internally and results in clutches of small jelly-like eggs.
Development is direct so the young hatch out of the eggs as miniature
adults. Observation of the noonday snail showed that it generally
follows this pattern (03,05). Immature snails with fewer whorls (thus
smaller overall size) and an unreflected lip were found in October
1983 (16,03). In April 1983 larger (almost full size) snails still
with unreflected lips were common (03,07). Most snails with complete
shells in April were just becoming sexually mature (05). The size
classes seemed uniform so there is probably a single breeding season
perhaps in mid-April or May. These adult animals were just over 1
year or just over 2 years in age (03,05,14).
PARENTAL CARE:
These snails are not known to exhibit any parental care.
POPULATION BIOLOGY:
No estimates of population size have been made since the exact
range has yet to be determined. Apparently suitable habitat occurs
for several miles along the gorge from the base to the crest of the
cliffs. Live snails in several size classes were found indicating
recent recruitment. Mature individuals (with complete, scuffed
shells) that had lived two or more winters were rarer than juveniles
or newly mature adults (03). This snail demonstrates the problem
inherent in sampling wild populations. Sample on a fine, warm summer
or fall day and the snails appear rare. Sample on a foggy spring day
with cool drizzle and the snail is everywhere (03,07,10,16). To look
for the snails in the cliff is to destroy the cliff.
SPECIES INTERRELATIONSHIPS:
A probable competitor for food and space is Mesodon wheatleyi
(03). Haplotrema concavum, a carnivorous land snail, is a confirmed
predator, and feral hogs, certain birds (e.g., wood thrush), certain
insects (lampyrid larvae), and small mammals (shrews) are all probable
predators (16,03,17).
OTHER LIFE HISTORY DESCRIPTORS:
None.
Life History - 2 (DRAFT) - Management Practices
Species SNAIL, NOONDAY
Species Id ESIS354003
Date 13 MAR 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Suppressing wildfire
Beneficial Restricting/regulating human disturbance of populations
Beneficial Controlling/Restricting Mining
Beneficial Controlling/Restricting Road Maintainance Actions
Beneficial Maintaining undisturbed/undeveloped areas
Beneficial Controlling/Restricting Herbicide Use
Beneficial Restricting Timber Harvest
Adverse Harassment/Vandalism/Indiscriminate Killing
Existing Harassment/Vandalism/Indiscriminate Killing
Adverse Rock Climbing
Existing Rock Climbing
Adverse Hiking/Camping
Existing Hiking/Camping
Adverse Recreational development
Existing Recreational development
Adverse Highway/Railroads
Existing Highway/Railroads
Adverse Vegetation Composition Changes
Existing Vegetation Composition Changes
Adverse Fire
Existing Fire
Adverse Forest Alteration
Existing Forest Alteration
Adverse Harvesting
Existing Harvesting
COMMENTS ON MANAGEMENT PRACTICES -
The noonday snail is known for certain only from a limited
habitat within the Nantahala Gorge. The area has undergone drastic
changes in the past. The forest composition was altered dramatically
with the extinction of the American chestnut. A road and a railroad
were both put through the gorge. Though the snail has tolerated these
changes, and though the threat of further habitat destruction to widen
U.S. Route 19 in the gorge has subsided (09), and the area has been
set aside from timber harvest (10), human activity in the gorge
(especially along the river) continues to increase (03). This
activity enhances the threat of forest fire or trampling which would
damage the unusual habitat that the snail needs. Another possible
threat is the encroachment of such non-native plants as kudzu.
Though the majority of the habitat is on U.S. Forest Service
land, the State of North Carolina is concerned enough about protecting
the area and excluding people from snail habitat that a proposal (11)
has been submitted to the Forest Service to designate the area around
Blowing Springs as a protected natural area. The recommendations
include some fencing of the area around the spring and a lack of
publicity about the designation.
Management Practices - 1 (DRAFT) - Management Practices
Species SNAIL, NOONDAY
Species Id ESIS354003
Date 13 MAR 96
APPROVED PLAN:
U.S. Fish and Wildlife Service. 1984. Noonday Snail Recovery Plan.
U.S. Fish and Wildlife Service, Atlanta, GA. 30 pp.
Recovery actions for the noonday snail include:
(1) Continue to utilize existing legal mechanisms to protect the
species and its habitat.
(2) Assess and monitor the population levels and habitat quality.
(3) Determine present and forseeable threats to the species.
Potential hazards include, forest fires, logging, road
construction/maintenance activities (including use of herbicides),
mineral mining, and increased human activity.
(4) Determine if other populations of the species exist.
Some searches have recently been made for the species outside its
known range. These have proved unsuccessful. Other surveys will be
conducted in the future.
Management Practices - 2 (DRAFT) - References
Species SNAIL, NOONDAY
Species Id ESIS354003
Date 13 MAR 96
References
***** REFERENCES FOR ALL NARRATIVES EXCEPT N-OCCURRENCE *****
01 Clench, W.J. and G.S. Banks. 1932. Descriptions of some land
snails of southwestern North Carolina. Nautilus 46(1):14-18.
02 Pilsbry, H.A. 1940. Land Mollusca of North America (North of
Mexico). Acad. Nat. Sci. Monogr. No.3. Vol.1. Part 2.
03 U.S. Fish and Wildlife Service. 1984. Recovery Plan for the
Noonday Snail. U.S. Fish and Wildlife Service. Atlanta, GA.
30 pp.
04 Hubricht, L. 1984. Correspondence to USFWS. 4026 35th St.,
Meridian, MS 39301.
05 Emberton, K.C. 1984. Personal communication. Invertebrates,
Field Museum of Natural History, Lake Shore Drive and Roosevelt
Road, Chicago, IL 60605.
06 Van Devender, A.S. 1984. Personal communication. Route 4, Box
441, Boone, NC 28607.
07 Fridell, J. and R.G. Biggins. 1984. Personal communication.
Endangered Species Field Station, 100 Otis St., Room 224,
Asheville, NC 28801.
08 Parker, W. and L. Dixon. 1980. Endangered and threatened wildlife
of Kentucky, North Carolina, South Carolina and Tennessee. N.C.
Agric. Ext. Serv.
09 Waters, T.L. 1983. Personal communication. Manager, Planning and
Research Branch, N.C. Dept. Transport., Raleigh, NC 27611.
10 Luckett, L. 1984. Personal communication. U.S. Forest Service,
Route 10, Box 210, Franklin, NC 28739.
11 Roe, C. and J. Moore. 1983. Recommendations to the U.S. Forest
Service regarding the designation of the noonday snail's primary
habitat (Blowing Spring - Nantahala Gorge) as a protected natural
area. N.C. Dep. Nat. Resour. Commun. Develop.
12 Braun, E.L. 1967. Deciduous Forests of Eastern North America.
Hafner Publ. Co., NY.
13 U.S. Fish and Wildlife Service. 1978. Determination that Mesodon
clarki nantahala is a threatened species. Federal Register
43:28932.
14 Blinn, W.C. 1963. Ecology of the land snails, Mesodon thyroidus
and Allogona profunda. Ecology 44(3):498-505.
15 Hyman, L.H. 1967. The Invertebrates: Volume VI, Mollusca I.
McGraw-Hill Book Co., NY.
16 Van Devender, R.W. 1984. Personal communication. Appalachian
State University, Department of Biology, Boone, NC 28608.
17 Yeatman, H. 1984. Personal communication. Box 356, Sewanee, TN
37375.
***** REFERENCES FOR N-OCCURRENCE NARRATIVE ONLY *****
01 Clench, W.J. and G.S. Banks. 1932. Descriptions of some land
snails of southwestern North Carolina. Nautilus 46(1):14-18.
02 Pilsbry, H.A. 1940. Land Mollusca of North America (North of
Mexico). Acad. Nat. Sci. Monogr. No.3. Vol.1. Part 2.
References - 1 (DRAFT) - References
Species SNAIL, NOONDAY
Species Id ESIS354003
Date 13 MAR 96
03 U.S. Fish and Wildlife Service. 1984. Recovery Plan for the
Noonday Snail. U.S. Fish and Wildlife Service. Atlanta, GA.
30 pp.
04 Parker, W. and L. Dixon. 1980. Endangered and threatened wildlife
of Kentucky, North Carolina, South Carolina and Tennessee. N.C.
Agric. Ext. Serv.
05 Hubricht, L. 1984. Personal communication. 4026 35th St.,
Meridian, MS 39301.
06 Roe, C. and J. Moore. 1983. Recommendations to the U.S. Forest
Service regarding the designation of the noonday snail's primary
habitat (Blowing Spring - Nantahala Gorge) as a protected natural
area. N.C. Dep. Nat. Resour. Commun. Develop.
References - 2