Key to Terrestrial Gastropods of
British Columbia
- 69a
- Animal with an exposed or partially exposed shell,
either plate-like or ear-shaped — 70
- 69b
- Animal without external shell — 72
- 70a
- Shell ear-shaped, at the posterior end of the
animal — Testacella haliotidea
Introduced to British Columbia (RBCM specimens).
- 70b
- Shell plate-like, near the longitudinal
middle of the animal — 71
- 71a
- Body immediately posterior to the visceral pouch
depressed to receive the visceral mass, then produced into a high,
compressed keel; caudal "horn" present — Hemphillia glandulosa
- 71b
- Body posterior to the visceral pouch not depressed
and not produced into a keel; horn absent — Hemphillia
species
One or possibly two species in addition to H. glandulosa
are present in British Columbia
-
72a
- Pneumostome at or behind the posterior 1/3 of
the mantle on the right side (see figure) — 73
- 72b
- Pneumostome at or in front of the midline of the
mantle on the right side — 77
-
- 73a
- Slug very narrow and wormlike (length about 15×
width when fully extended); mantle with a groove present on its
right side — Boettgerilla pallens
Introduced to British Columbia (Reise
et al. in press)
- 73b
- Slug not wormlike; mantle groove absent
— 74
- 74a
- Mantle smooth; caudal mucous pore conspicuous
— Ariolimax columbianus
- 74b
- Mantle with concentric wrinkle-like folds
(somewhat like a finger print); caudal mucus pore absent —
75
- 75a
- Mantle with distinct, dark lateral bands —
Lehmannia cf. valentiana
Introduced to British Columbia (RBCM specimens)
- 75b
- Mantle unicolour, spotted or marbled, but
without bands — 76
- 76a
- In side view, tail tapering to a point; mantle
with its posterior edge angular; concentric rings on the mantle
centred on the midline — Limax
maximus
- 76b
- In side view, tail abruptly truncated; mantle
with its posterior edge rounded; concentric rings on the mantle
centred to the right of the midline, near the pneumostome —
Deroceras species
Four species are known to occur in British Columbia: Deroceras
laeve; Deroceras hesperium; Deroceras
reticulatum; and Deroceras panormitanum [=caruanae].
Most species are not easily differentiated by external characters.
- 77a
- Tail often having an oblique constriction which
marks the site of self-amputation; caudal mucous pore absent —
78
- 77b
- Tail never having an oblique constriction;
caudal mucous pore present — 80
- 78a
- Body with a conspicuous black band on either side
running from the mantle to tip of the tail and enclosing a lighter,
wedge-shaped central area which may enclose another darker median
stripe — Prophysaon vanattae
- 78b
- Body without black bands behind the mantle
(but mantle may be banded) — 79
- 79a
- Length to about 50 mm; mantle without yellow border;
constriction usually marked by a grey line on the sole —
Prophysaon andersoni
(Figure)
- 79b
- Length 50-100 mm; mantle often with a narrow,
bright yellow border; constriction usually not marked by a grey
line on the sole — Prophysaon foliolatum
- 80a
- Adult animal very large, greater than 70 mm in
length when extended — Arion
rufus
- 80b
- Adult animal smaller, less than 70 mm in
length — 81
- 81a
- When animal contracted, tubercles have a prickly
appearance; length of adult (fully extended) to about 15 mm —
Arion intermedius
- 81b
- When contracted, tubercles without a prickly
appearance; length of adult greater than 15 mm — 82
- 82a
- Body with ground colour of reddish brown, rusty-orange
or occasionally yellow; body mucus yellow or orange; slugs cannot
contract into a hemispherical shape (in lateral view) — Arion
subfuscus
- 82b
- Body with ground colour of light greyish,
brownish grey, dark grey or bluish-grey; body mucus colourless;
slugs can contract into a hemispherical shape — 83
- 83a
- Ground colour of light greyish or brownish grey;
a pale line present on back, forming a "false keel"; body of contracted
animal bell-shaped in cross-section (see figures below) —
Arion fasciatus species complex
Species in this complex are not always reliably distinguishable
by external characters alone. Dissection may be required.
- 83b
- Ground colour of dark dark grey or bluish
grey (sometimes tinged with reddish); no "false keel"; body of
contracted animal not bell-shaped in cross-section (see figure)
— Arion hortensis species complex
Species in this complex are not reliably distinguishable by
external characters alone. Dissection is required.
Cross-section of body: Arion
fasciatus species complex (left)
and Arion hortensis species complex (right)
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