Key to Terrestrial Gastropods
of British Columbia
- 17a
- Parietal denticle present - 18
- 17b
- Parietal denticle absent - 20
- 18a
- Periostracal hairs usually persistent in the adult;
shell width to about 7 mm - Cryptomastix germana
- 18b
- Periostracal hairs not usually persistent
in the adult; shell width greater than 12 mm - 19
- 19a
- Shell width 12-26 mm; basal lip denticle or swelling
(at its thickest point) located relatively closer to the columella
than the periphery; southwest coastal British Columbia - Cryptomastix
devia
- 19b
- Shell width 12-19 mm; basal lip denticle
or swelling (at its thickest point) located relatively closer
to the periphery than to the columellar; in southeast British
Columbia - Cryptomastix
mullani (Figure)
- 20a
- Umbilicus absent - 21
- 20b
- Umbilicus open, although often slitlike or
just a tiny pit - 26
- 21a
- Shell width greater than 15 mm and usually with
colour spiral bands, but sometimes without - 22
- 21b
- Shell width less than 5 mm and without colour
bands - 23
- 22a
- Aperture height less than its width; unicolour
or typically banded, with bands continuous, seldom interrupted
by axial streaks - Cepaea
nemoralis
- 22b
- Aperture height about equal to its width;
banded, with bands usually interrupted by light-coloured axial
streaks - Helix aspersa
- 23a
- Aperture broadly and deeply rounded; whorls about
3 - Vitrina
pellucida (Figure)
- 23b
- Aperture narrowly crescent-shaped; whorls
3½ or more - 24
- 24a
- Whorls with distinct axial grooves between the
periphery and the suture in addition to very fine axial striae
- Pristiloma stearnsii
- 24b
- Whorls with fine axial striae (and sometimes
spiral striae) only - 25
- 25a
- Shell waxy white or colourless; height of shell
less than or equal to ½ of its width - Pristiloma
johnsoni
- 25b
- Shell brownish; height of shell greater than
½ its width - Pristiloma lansingi
- 26a
- Shell width greater than or equal to 6 mm - 27
- 26b
- Shell width less than 6 mm - 47
- 27a
- Shell with colour bands - 28
- 27b
- Shell without colour bands - 31
- 28a
- Columellar lip expanded to almost close the umbilicus,
leaving only a narrow slitlike opening - 22
- 28b
- Columellar lip overhanging the umbilicus,
but not enough to leave only a narrow slitlike opening - 29
- 29a
- Shell brown with a narrow, pale, somewhat yellowish
band at the periphery, a narrow, dark brown band above this and
a dark brown base; shell rarely yellow with pale banding; animal
with a reddish tinge; coastal British Columbia - Monadenia
fidelis
- 29b
- Shell greyish to brown, and banding not as
above; animal not with reddish tinge; SE British Columbia - 30
- 30a
- Shell dark brown, generally with a lighter peripheral
band obscurely bordered by a darker band on either side; this
light band visible within the aperture - Anguispira
kochi (Figure)
- 30b
- Shell generally greyish or brownish grey
with two or more (often interrupted) dark bands (but banding is
highly variable and may be absent) and speckling; dark bands often
visible within the aperture - Oreohelix
strigosa & O.
subrudis
O. subrudis usually has a more elevated spire than O.
strigosa, but identification by this shell character can be
unreliable.
- 31a
- Periostracum with minute hairs - 32
- 31b
- Periostracum without hairs -
33
- 32a
- Lip flared, sometimes a little recurved, thin-edged
- Vespericola columbianus
- 32b
- Lip flared, strongly recurved, edge appearing
thick due to the tight scroll-like folding back of the edge -
Cryptomastix mullani (Figure)
Cross-section of the lip of Vespericola columbianus
(top)
and Cryptomastix mullani (bottom)
- 33a
- Shell with prominent, sharply defined regular axial
ribs (at least on the upper surface of the whorls of the spire)
- 34
- 33b
- Shell without axial ribs, or axial ribs weak
or not regular - 37
- 34a
- Outer lip straightened or concave at shoulder in
apertural view - 35
- 34b
- Outer lip more or less convex at shoulder
in apertural view - 36
- 35a
- Beaded sculpture present on all whorls of the shell;
width to 18 mm - Ancotrema sportella
- 35b
- Beaded sculpture obsolete on the penultimate
and/or last whorl; width to 27 mm - Ancotrema
hybridum
- 36a
- Axial ribs about as strong on the base as on the
apical surface of the shell - Discus
whitneyi
- 36b
- Axial ribs absent or significantly weaker
on the base than on the apical surface of the shell - Discus
shimekii
- 37a
- Lip strongly expanded and curved back to form a
more or less broad, flattened face throughout its length - 38
- 37b
- Lip thin or slightly thickened but not greatly
expanded into a flat face; the lip of Cepaea
nemoralis is somewhat expanded at the periphery but
not elsewhere along its length - 40
- 38a
- Sculpture of irregular, rounded axial ribs, strongest
near the suture and usually disappearing below the periphery;
width greater than 19 mm - 39
- 38b
- Sculpture of fine axial striae only; width
9-17 mm - 40
- 39a
- Shell width 21-31 mm; surface sculpture often malleated;
apparently restricted in British Columbia to the vicinity of the
Chilliwack Valley - Allogona townsendiana
- 39b
- Shell width 19-24 mm; sculpture seldom malleated;
southeast British Columbia - Allogona
ptychophora
- 40a
- Whorls about 3; shell pale, greenish, yellowish-green
or nearly colourless - Vitrina
pellucida
- 40b
- Whorls about 4-6; shell amber-coloured or
pale brown, often paler around the umbilicus - 41
- 41a
- Columellar lip expanded over to almost close the
umbilicus, leaving only a narrow slitlike opening - Cepaea
nemoralis
- 41b
- Columellar lip may overhang the umbilicus,
but not enough to leave only a narrow slitlike opening - 42
- 42a
- Axial sculpture rather rough and irregular and/or
shell width usually greater than 16 mm - 43
- 42b
- Shell smoothish; width less than or equal
to 16 mm - 44
- 43a
- Shell yellowish, olive green or darker; outer lip
straightened at shoulder in apertural view - Haplotrema
vancouverense
- 43b
- Shell greyish white or occasionally more
brownish; outer lip convex at shoulder - Oreohelix
strigosa & O.
subrudis
O. subrudis usually has a more elevated spire than O.
strigosa, but identification by this shell character can be
unreliable.
- 44a
- Umbilicus about 25% of the shell width; shell with
very fine, faint spiral striae - Aegopinella
nitidula
Introduced to British Columbia (Forsyth et al. in prep.)
- 44b
- Umbilicus about 15% of the shell width; shell
without spiral striae - 45
- 45a
- Animal with a strong garlic odour when disturbed;
shell to about 7 mm - Oxychilus alliarius
Introduced to British Columbia (Forsyth
in press)
- 45b
- Animal greyish, bluish-grey or nearly black,
never with a garlic odour; shell greater than or equal to 7 mm
- 46
- 46a
- Shell to about 10 mm in width; last whorl regularly
expanding; shell usually very glossy and with only very weak striae
if any; animal pale grey with minute brown specks on the edge
of the mantle (evident near the pneumostome on the right side,
and on the left side through the shell) - Oxychilus
cellarius
Introduced to British Columbia (Forsyth
in press)
- 46b
- Shell larger, to 12-16 mm in width; last whorl
more rapidly expanded near the aperture so that it appears more
than twice as wide as the previous whorl; shell usually less glossy
and more striate than above species; animal dark bluish grey - Oxychilus
draparnaudi
Introduced to British Columbia (Forsyth
in press)
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