Geomalacus grandis Simroth, 1894
Letourneuxia lusitana Castro, 1873
Kerry slug or Kerry spotted slug (
Geomalacus maculosus) is a rare
species of medium-sized to large air-breathing land slug. It is a
terrestrial pulmonate gastropod mollusc in the family Arionidae, the
Kerry slug generally measures 7–8 cm
(2.8–3.2 in) in length and is dark grey or brownish in colour,
with yellowish spots. The internal anatomy of the slug shows some
unusual features, and some characteristic differences from the genus
Arion, which is the type genus of the family Arionidae. The Kerry slug
was described in 1843, rather late compared to many other relatively
large land gastropods that form a part of the fauna of
Britain; this is one indication of this slug's rarity and its
Although the distribution of this slug species does include some wild
habitats in southwestern
Ireland (e.g. in County Kerry), the species
is more widespread in north-west
Spain and from central to northern
Portugal. However, it is not found anywhere between
Ireland and Spain.
The species appears to require environments that have high humidity
and acidic soil (soil with no calcium carbonate in it). The slug is
mostly nocturnal or crepuscular, although in
Ireland it is active on
overcast days. It feeds on lichens, liverworts, mosses and fungi,
which grow either on boulders or on tree trunks.
This rare species is officially protected by conservation laws in each
of the three countries in which it occurs. However, the survival of
Kerry slug is nonetheless threatened because it lives only in
completely wild, unspoiled habitat of a particular type: acidic
woodlands and moorlands that support the species of lower plants on
which the slug relies for food. This habitat type is itself at risk
from a number of different factors, ranging from climate change to the
construction of roads. Attempts have been made to establish breeding
populations in captivity, to help ensure the survival of this slug
species, but with only limited success.
2.1 Internal anatomy
2.1.2 Various organ systems
2.1.4 Reproductive system
2.1.5 Apparatus for feeding
3.1.1 Protected sites
Spain and Portugal
22.214.171.124 Protected sites
5.3 Life cycle
6 Threats to the survival of the species
7 Conservation measures
7.1 International protection
7.2 Protection in Iberia
7.3 Protection in Ireland
7.4 Captive breeding
9 Further reading
10 External links
Kerry slug is a gastropod, as are all other snails and slugs,
including slugs and snails that live in saltwater, those that live in
freshwater, and those that live on the land. This is a land slug which
breathes air, a pulmonate. It is in the clade Stylommatophora, which
means that its primitive eyes or eye spots are carried on the tips of
its two upper tentacles. Despite superficial similarities, not all
land slugs are in the same family or superfamily. The
Kerry slug is an
arionid, or round-backed slug; it has no keel on its back, in contrast
to the land slugs in the family
Limacidae and Agriolimacidae. It also
shares numerous internal anatomical features with slug species in
other genera within the family Arionidae, including the Arion slugs,
which are most typical of the family.
The Kerry slug's scientific name or binomial name is Geomalacus
maculosus. It is in the genus Geomalacus, a name which literally means
"earth mollusc". Its specific name maculosus means "spotted", from the
Latin word macula "spot". The English language vernacular name (or
common name) is derived from the name of County Kerry, which is the
county in the southwest of
Ireland where this species was first
collected, and which is also the type locality, as mentioned in the
The scientific name of the species is also sometimes written as
Geomalacus (Geomalacus) maculosus. This is because the genus
Geomalacus contains two subgenera: the nominate subgenus (subgenus of
the same name)
Geomalacus and a second subgenus Arrudia Pollonera,
1890. The subgenus
Geomalacus contains only one species, the Kerry
slug. The subgenus Arrudia includes three species.
This slug species was originally described and named from specimens
collected in Ireland. In 1842, an Irish naturalist named William
Andrews (1802–1880) sent material that he had found at Caragh Lake
County Kerry to the Irish naturalist George James Allman, who
then introduced the slug to science as a new species.
Kerry slug has been included in molecular phylogenetic studies
Colour variation in three individuals, lighter and darker; the lower
two having indistinct banding
The body length of adult slugs of this species is 7–8 cm
(2.8–3.2 in). However it is difficult to measure these slugs
accurately because of their unusual startle response (see the section
entitled behaviour). Kerry slugs can also elongate themselves within
crevices up to 12 cm (4.8 in). "Official" measurements of
this species vary; for example, Kerney et al. (1983) give a range
of measurements for the species: 6–9 cm (2.4–3.6 in).
The body of a fixed (preserved) adult specimen was 7 cm
(2.8 in) long with a mantle length of 3 cm (1.2 in).
Colour morphs of G. maculosus. Brown individuals are typically
associated with woodlands; black individuals are found in open
habitats such as blanket bog or heath.
The body of these slugs is glossy, and is covered on the left and
right sides with about 25 longitudinal rows of polygonal granulations
(very small knobs with outlines like polygons).
The slugs have two colour morphs depending on the type of habitat
where they are found, suggesting that they are using camouflage.
There can also be variation in relation to banding. On each side of
the body there can be two bands: one band just below the summit of the
back, and the other band further down the side of the body. When these
bands are present they usually extend the whole length of the body of
the slug, and are overspread by numerous, somewhat oval, yellowish
spots. These yellow spots are distributed more or less in five
The caudal end (tail end) of the body showing supra-pedal grooves and
triangular caudal mucous pit
Right view of the tail end of the body.
Behind the animal's head, the "shield" (the shield-shaped outer
surface of the mantle) is about a third of the length of the body when
the slug is actively crawling and thus extended, but only about half
of that when the slug is motionless and contracted. The shield is
rounded in front, and bluntly pointed behind. The texture of the
surface of this area resembles the underside of undyed leather. It is
spotted with pale buff or whitish spots which are similar to those on
the body, but more uniformly distributed.
The foot-fringe (a band of tissue around the edge of the foot) is not
very distinctly separated: it is very pale and somewhat expanded, with
indistinct lines on it. The sole (the underside) of the foot is a
pale grayish-yellow in colour, and is divided into three indistinct
bands, with the mid-area being somewhat darker and more transparent
than the side bands. There is a caudal mucous pit situated between
the foot and the body on the upper surface of the tip of the tail. The
pit (which collects extra mucus) is not very conspicuous, but it is
triangular in shape and opens transversely (i.e. from side to side).
The mucous pit often carries a transparent yellowish ball of slime
The upper tentacles are smoky-black or grey, short and thick, with
oval ends, and have the usual eye spots at their tips. The genital
pore (or opening) lies behind and below the right eye-tentacle.
The lower tentacles are pale translucent grey. The skin mucus is
usually pale yellow, and varies in its degree of viscosity
(stickiness). The locomotory-mucus (mucus for crawling on) is
tenacious and usually colourless, but it can be yellowish because of
having mixed with the body slime.
Most land slugs have, within the mantle, the remnants or residue of
what was, in the evolutionary past, a larger external shell. In most
slugs, this remnant takes the form either of a small internal shell (a
thin shelly plate), or a collection of calcareous (chalky) granules.
In this species there is an internal shell or shell plate which
resembles that found in land slugs of the genus Limax. In other words,
the shell plate in this species is oval in shape, solid, and chalky,
with a transparent conchiolin (horny) base. The shell plate is usually
somewhat convex above and concave beneath, with a few indistinct
concentric lines of growth, and is covered outwardly with a very thin
transparent periostracum (a protein layer), and with the nucleus (the
oldest growth part) situated near the front. In young Kerry slugs the
shell is very thin and convex, abruptly cut off behind, and with an
extremely thin layer that projects in front and contains minute
The shell plate has been drawn differently by authors, but do at least
show that it is a solid plate:
The internal shell as drawn by Taylor in 1907
The internal shell as drawn by Godwin-Austen in 1882
Photograph of internal shell of G. maculosus (dorsal view).
Various organ systems
Anatomy viewed from below with frontal edge of mantle on the top.
Heart (red) is surrounded by renal organ (yellow). Retractor muscles
(blue) include retractor muscle of left eye tentacle (depicted on the
right), retractor muscle of right eye tentacle and retractor muscle of
odontophore (both on the left).
The cerebral ganglia, a central processing area which is equivalent to
the brain within the nervous system of the slug
The circulatory and excretory system are closely related, in that the
heart is surrounded by the triangular kidney. The kidney has a
lamellate (layered) structure and it has two ureters. In this slug
species, the ventricle of the heart is directed towards, and is very
close to, the anal and respiratory openings. The ventricle of the
heart is further away and further back than it is in species of the
related genus Arion, the type genus of the family Arionidae.
The gland above the foot, the suprapedal gland, is deeply imbedded in
the tissues, and reaches far back. The cephalic (head) gland known as
Semper's organ is well developed, and shows as a pair of strong
flattened lobes. The salivary and digestive glands are the same as
those found in Arion species, but the vestigial osphradium
(kidney-like structure) within the mantle chamber is more distinct
than it is in Arion species.
As for the various muscles within the slug, the cephalic retractors
(muscles for pulling in the head) are very much the same as they are
in Arion species. The right and left tentacular muscles, which pull in
all four of the tentacles, divide early for the upper and lower
tentacles, but only the muscles of the ommatophores (the muscles of
the two upper tentacles, which have eye spots) are darkly pigmented.
The right and left muscles that pull in the eyespot tentacles are
attached at the base to the back edge of the mantle, on the right and
left respectively. The pharyngeal (throat) retractor muscle is, as
usual, furcate (split) for attachment to the back of the buccal bulb
(mouth bulb), and the root of this muscle is fixed on the right side
of the body, just behind where the right tentacular muscle is
Kerry slug is hermaphrodite as all other pulmonates. Its reproductive
system is diagnostic feature. The genus
Geomalacus has a special
feature: the atrium has a diverticulum. This atrial diverticulum is an
elongated part of the atrium. The penis in the genus
reduced and lost as well its penial retractor muscle. The atrial
diverticulum is a secondary penial structure and with its spermatheca
retractor muscle acts as a copulatory organ instead. The other end
of the spermatheca retractor muscle extends to the posterior end of
the body. The atrial diverticulum has been proposed to be the
morphological equivalent (analogy, homoplasy) of a penis.
Geomalacus maculosus has an atrial diverticulum longer than the
spermatheca duct, while
Geomalacus anguiformis has an atrial
diverticulum shorter than the spermatheca duct.
Various authors have depicted the reproductive system of Kerry slug:
Godwin-Austen (1882), Sharff (1891), Simroth (1891,
1894), Taylor (1907), Germain (1930), Quick (1960)
and Platts & Speight (1988). Platts & Speight (1988)
consider from previous authors depiction by Godwin-Austen (1882)
to be the most accurate, because other authors depicted atrium too
The Kerry slug's reproductive organs are as follows: there is a small,
compact, and darkly pigmented ovotestis (a combination of ovary and
testis). There is a hermaphroditic duct (male and female duct) which
is very long and greatly convoluted, and ends in a small spherical
vesicula seminalis (seminal vesicle). The albumen gland (which creates
albumen for the eggs) is elongated and shaped like a tongue. The
ovispermatoduct (a duct that carries both eggs and sperm) is very much
twisted. The free oviduct (duct that carries eggs only) is rather long
and thin, but without any enlargement.
The vas deferens (carries sperm) is very long, complexly twisted, and
rolled up in the form of a bundle. The spermatheca (for storing sperm)
is globular, with a short stem, but is quite distant from the genital
pore (where the whole elaborate system opens to the outside world).
The spermatheca is distant from this opening because of the remarkable
elongation of the atrium or vestibule (a common area which is usually
just inside the genital pore, the atrium is an area where both the
male and the female systems open). There is a long retractor muscle
from the vesicle, and its stem is fixed internally to the back of the
slug in the median line (midline of the body) near the caudal end
(tail end) of the body. The vas deferens and the spermatheca open
nearly together into the far extremity of the atrium, which is
prolonged in an attenuate form (drawn out in length) to an enormous
extent. The very thin free oviduct (egg-carrying duct) opens into the
atrium much nearer the near end, where the muscular vestibule is
greatly but irregularly enlarged, and connected to the oviduct by a
number of muscular fibres.
Within the vagina (the female organ which receives the copulatory
organ during copulation) there is a curious series of flattened folds,
the central part has a pointed end which is situated close to the
genital pore, and this pointed end may possibly be a sarcobelum (a
very much reduced version of an organ that makes love darts) and thus
may be the homologue (a similar structure because of shared ancestry)
of the love dart in the Helicidae.
The reproductive system by Godwin-Austen (1882). The large mass on
the right is albumen gland, the mass on the lower part right is the
ovotestis, the oval shape at the left is the spermatheca. Mantle edge
and atrium is at the top.
Drawing of "male part" of the reproductive system. From lower left to
upper left: genital pore, atrium, atrial diverticulum, spermatheca
duct, spermatheca retractor muscle, spermatheca. On the top right:
epiphallus. Center: vas deferens. Lower right: free oviduct,
Apparatus for feeding
The radula is a feeding structure found only in molluscs. Typically it
is a small but strong ribbon-like structure with numerous complex rows
of tiny teeth across it. The radula is situated inside the mouth.
In this species of slug, the radula is 8 mm (5/16 in) long and
2 mm (1/16 in) wide, and has 240 slightly curved transverse
(crosswise) rows of denticles (tiny teeth). Each row of teeth is
composed of one median tooth and 10 lateral and marginal teeth on each
side. The median teeth are small, and are clearly unicuspid (having
one cusp), though they are slightly shouldered. The lateral teeth are
bicuspid (having two cusps) but the admedian (next to the middle)
teeth are noticeably larger than the median row, and the mesocone (an
extra protrusion in the middle of the tooth) is well developed. There
is however, no distinction between the lateral and marginal series
except that the ectocone (extra little side protrusion) present on the
admedian teeth recedes in position and slightly diminishes in size in
the succeeding teeth up to about the twentieth row on the radula, but
in the marginal series, the ectocone gradually grows in size and
importance as the margin is approached, while the mesocone becomes
almost correspondingly diminished, the outermost teeth showing a more
embryonic (more like that of an embryo) character.
One complete row of teeth in the radula
The jaw, which has broad ribs.
The jaw measures about 1 mm (1/32 in) from side to side, and is
distinctly arcuate (arched) from front to rear, lunate (crescent-moon
shaped) in shape, but very wide, with broad and slightly rounded ends.
The jaw is solid, dark-brown and has about 10 broad flat ribs only in
the middle part of the jaw. These ribs are absent or scarcely
discernible on the side areas. Where the ribs meet the upper edge they
sometimes form crenulations ( a scalloped effect) and may also produce
the same effect on the lower edge of the jaw. In other individuals the
ribs extend all the way across the jaw, making both the upper and the
cutting edges of the jaw clearly denticulate (noticeably toothed in
The alimentary canal of the digestive system forms two loops, as is
true of all species within the family Arionidae.
Distribution map for the species. It shows the "Lusitanian" type of
disjunct distribution, but not the recently discovered Co. Galway
Geomalacus maculosus has what is known as a disjunct distribution (in
other words, it occurs in discontinuous locations). This slug is found
only in southwestern Ireland, north-west Spain, and from central
Portugal to northern Portugal. The presence of this slug in
Ireland might seem anomalous, but similar distribution
patterns have been observed in a few other species of animals and
plants. This particular disjunct distribution (in Iberia and in
Ireland without any intermediate localities) is known as "Lusitanian".
There has been speculation that the G. maculosus was introduced to
Ireland from Iberia by prehistoric humans, as appears to have happened
in the case of the Eurasian pygmy shrew. In support of this,
the genetic diversity of the slug in
Ireland was found to be greatly
reduced compared with the Iberian populations.
Within Ireland, this species of slug is known from areas with
sandstone geology in
West Cork and County Kerry, a total area of
around 5,800 km2 (2,200 sq mi). In 2010, a
previously unknown population of the Kerry
Slug was recorded in a
third county, Co. Galway.
A significant proportion of the Kerry slug's range in
protected by being included in
Special Areas of Conservation
Special Areas of Conservation (SACs).
Ireland's response to the European environmental legislation
concerning the slug is discussed in greater detail in the Conservation
Measures section below.
A total of seven
Special Areas of Conservation
Special Areas of Conservation have been designated
with the slug as a "selection feature":
Glengarriff Harbour and Woodland
Killarney National Park,
Macgillycuddy's Reeks and Caragh River
Lough Yganavan and Lough Nambrackdarrig
Cloonee and Inchiquin Loughs, Uragh Wood
Blackwater River (Kerry).
St. Gobnet's Wood SAC (which was designated in relation
to other selection criteria) was expanded in 2008 to protect Cascade
Wood, a small area of woodland which is inhabited by the slug.
The species has also been recorded at other SACs where it is not a
selection feature, for example Derryclogher Bog in County Cork.
Spain and Portugal
Despite its first "discovery" at Caragh Lake, and its English common
name of "Kerry slug",
Ireland is not at the centre of this slug
species' distribution; instead the distribution of this slug is
centred in continental Iberia. This slug has been known from
Spain since 1868, and from northern
Portugal since 1873.
It was once reported as occurring in France, but this was never
confirmed, and so that record is considered suspect.
The southernmost locality where this species is found is the mountain
Serra da Estrela
Serra da Estrela in Portugal. Other Portuguese localities
include the provinces Beira Alta, Douro Litoral, Minho,
Trás-os-Montes e Alto Douro and the Peneda-Gerês National Park, a
The distribution of this species in
Spain includes coastal locations
in Galicia, and extends through the
Cantabrian Mountains as far east
Ganekogorta in the Basque Country. The localities in question
fall within the boundaries of various autonomous communities: Galicia,
Castile and León
Castile and León (provinces of León, Palencia
and Zamora), and the Basque Country (provinces of
Álava). There have been unconfirmed findings of this slug
reported from Navarra.
Natura 2000 sites for this species in
Spain include 48 localities
(listed below, grouped by region). As at 2017 some of these sites have
yet to be designated as
Special Areas of Conservation:
Muniellos; Ponga—Amieva; Redes;
Special Area of Conservation;
Protection Area); "Upper valleys of the Nansa and Saja and Alto
Castile and León
Hoces de Vegacervera; Lake Sanabria and its vicinities; Montes
Aquilanos (Site of Community Importance);
Montes Aquilanos y Sierra de
Natural Park of Fuentes Carrionas and Fuente Cobre-Montaña Palentina
Sierra de la Cabrera
Sierra de la Cabrera (SCI partially overlapping with a SPA of
the same name).
Anllóns river; Baixa Limia; Baixa Limia - Serra do
Xurés; Baixo Miño; Bidueiral de Montederramo; Carballido, a yew wood
in A Fonsagrada;
Carnota - Monte Pindo; Cíes Islands; Costa Ártabra;
Costa da Morte
Costa da Morte - two areas,
Costa da Morte
Costa da Morte and Costa da Morte
(Northern); Cruzul-Agüeira; Encoro de Abegondo-Cecebre; Eo river
(included among the Galician sites although the estuary forms the
boundary with Asturias); Costa de Ferrolterra-Valdoviño; Fragas do
Eume; Macizo Central, Ourense (province); Monte Aloia; Monte Maior;
Negueira; Pena Trevinca; Pena Veidosa; Serra do Candán; Serra do
Cando; Serra do Xistral; Sil river canyon; Sobreirais do Arnego;
Tambre - two areas, the river and its estuary; Támega river;
Ulla-Deza river system
More than one region
Ancares - This district is divided between Galicia and Castile and
León. Sierra de los Ancares is a mountain range which forms the
boundary between the two autonomous communities, and which gives its
name to a
Natura 2000 site in the province of León. On the
Galician side of the sierra are two relevant sites - Ancares
(protected under the Birds Directive) and Ancares-Courel (protected
under the Habitats Directive).
Picos de Europa
Picos de Europa - This mountain range is divided between three
autonomous communities. The three sites listed (Picos de Europa, Picos
de Europa (Asturias),
Picos de Europa
Picos de Europa en Castilla y León) include
protected areas in the
Picos de Europa
Picos de Europa National Park, and a regional
park in Castile and Leon which is also called Picos de Europa.
The alarm response posture, which is found only in this species
This species of slug is primarily nocturnal, in other words it is
usually only active at night. During the daylight hours, these slugs
are usually hidden in crevices of rocks and under loose bark on
trees. In Iberia, juvenile slugs of this species become active
during twilight, and adults become active at night, especially on
rainy or very humid nights.
Ireland however is much further
north, so the temperatures there are considerably cooler, there is
more rain, and the air is often quite damp; in
Ireland this slug is
sometimes active in the daytime as long as the weather is humid and
Kerry slug has a defensive behavior that is very unusual in slugs.
When attacked, most land slugs will simply retract the head and
contract the body, but stay firmly attached to the substrate. In
contrast, when this slug is threatened, it retracts its head, lets go
of the substrate, rolls up completely, and stays contracted in a
ball-like shape. This is a unique feature among all the
Arionidae, and among all slugs in Ireland.
Kerry slug eats liverworts, probably including this species Pellia
epiphylla, which is found in localities where the slug occurs in
Two individuals among lichen patches on a rock are not easy to see
because of their protective colouration.
Geomalacus maculosus lives only in wild habitats and thus it is
never an agricultural pest, unlike some other slugs in the family
Ireland this slug inhabits wild woodland with oak trees, and
oligotrophic open moorlands, as long as there are boulders covered
with lichens and mosses in these habitats. In
Spain it usually
occurs in granite mountains.
Kerry slug usually prefers acidic soil and high humidity
environments, living on moss and lichen-covered rocks and trees
(mainly the chestnut
Castanea sativa and some species of oak), under
fallen wood and under bark of rotten wood. It may also occur in
open areas, such as hydrophilic pastures near oligotrophic water
The food of
Geomalacus maculosus includes lichens, liverworts, mosses,
fungi (Fistulina hepatica) and bacteria that grow on boulders and
on tree trunks.
In captivity, this species has been fed on porridge, bread, dandelion
Cladonia fimbriata and various vegetables: (carrot,
cabbage, cucumber, lettuce). It can be also carnivorous in
captivity, and has been documented as devouring the snail Vitrina
A cluster of eggs deposited in captivity
The mating of this species is in head-to-head position with genital
openings facing each other. Atria are shaped as a funnel with
fluted edges after mating. As in Arion, sperm is transferred in a
spermatophore. Eggs are laid in July to October in the wild,
and from February to October in captivity.
also possible in this species. The eggs are laid in clusters of 18
to 30, and held together by a film of mucus. The egg masses are
about 3.5 × 2 cm in overall size.
The eggs are very large compared with the size of the animal, but vary
within certain limits. The largest eggs are more elongate, being 8.5
× 4.25 mm; the smallest eggs are more regularly oval, and are
only 6 × 3 mm. All are semitranslucent milky-white or opalescent
when fresh, although some of the larger and more elongate ones
show a somewhat transparent area at the smaller end. The opalescent
(the color changes with the light direction like an opal) lustre
becomes lost in a few days, and the eggs turn yellowish, and later
brown, or black.
The young appear to hatch in from 6 to 8 weeks, at which period
the spots on the body of the animal are barely present. However, the
lateral bands are distinct and black, much more conspicuous than they
are in mature slugs of this species. In juveniles the shield shows
lyre-shaped markings, as is the case in slugs of the genus Arion.
However these lyre-shaped markings become indistinct as the slugs grow
larger. The slugs probably pass the winter in the sexually immature
stage. The body of preserved juvenile specimens is up to 3 cm
(1.2 in) long with a mantle length of 10 mm. Juveniles
reach maturity in 2 years, at a length about 2.6 cm. The
life span of
Geomalacus maculosus in the wild is up to seven years,
but the lifespan in captivity is rarely over three years. In
numerous different localities in Spain, it was consistently found to
be the case that no more than a very few individuals of the species
were observed at any one time.
There were not known natural enemies of
Geomalacus maculosus up to
2014. Predators of
Geomalacus maculosus include larvae of the
third instar of the fly Tetanocera elata.
Threats to the survival of the species
One threat to the habitat of this slug is the invasive plant species
Rhododendron ponticum, as shown flowering here in Killarney National
The most serious threat to the species is probably modification of the
habitat, which reduces its lichen and moss food sources. This can
lead to the local disappearance of the species, which was documented
in Spain. Other threats include: intensification of land use
(land reclamation, using of pesticides, overgrazing by sheep, removing
of shrubs, building gardens, burning, and building roads and
highways), tourism, general development pressure, coniferous forest
plantations, the spread of invasive species of plants such as
Rhododendron ponticum and habitat fragmentation (see also
Other potential dangers to the species include climate change and air
pollution, because these negatively affect the lichens which are a
food source for the slug.
Climate change will probably affect the
Iberian populations more seriously, because the climate there is
already on the hot and dry side relative to Ireland, which is
generally rather cool and damp.
Because of its perceived rarity and its restricted distribution,
Geomalacus maculosus is protected under the Convention on the
Conservation of European Wildlife and Natural Habitats (Bern
Convention), EIS Bern Invertebrates Project. This decision was backed
by studies of its distribution and ecology in Ireland which
concluded that evidence of a decline in Iberia, plus uncertainty over
its status in Ireland, tended to support its inclusion in the
Convention. Since 2006,
Geomalacus maculosus has been considered a
least concern species in the IUCN Red List, however, during 1994 to
2006 the slug was rated as vulnerable.
Geomalacus maculosus is also protected by the European Union's
Habitats Directive (which was a response to the Bern Convention) and
has been listed as an Annex II and Annex IV species since 1992.
There are two principal mechanisms used by the Directive to protect
habitats and species:
the creation of
Special Areas of Conservation
Special Areas of Conservation (SACs)
the protection of species independently of their habitats by other
Seven SACs have been designated for this species in
Ireland and 49
SCIs in Spain. It is probably in areas not specifically protected
as SACs that threats to the
Kerry slug will be greatest. The Habitats
Directive protects the
Kerry slug outside the SACs by Article 12 (1),
which obliges European Union member states to:
establish ‘a system of strict protection’ for listed species
prohibit deliberate capture or killing
prohibit ‘deliberate disturbance … particularly during the period
of breeding, rearing, hibernation and migration’
prohibit ‘deliberate destruction or taking of eggs from the wild’
prohibit the deliberate or non-deliberate ‘deterioration or
destruction of breeding sites or resting places’.
Protection in Iberia
Conservation status reports from
Portugal and from
Spain were not yet
available in August 2009.
Its conservation status in
Spain for the IUCN criteria is
Protection in Ireland
In 1988 Platts and Speight noted that only three of the Irish sites
where the slug occurred were protected: Glengariff Forest, West Cork;
Uragh Wood Nature Reserve, South Kerry; and Killarney National Park,
North Kerry. They concluded that the species could not be adequately
safeguarded with only three sites, and therefore they supported its
inclusion in the Bern list, to which the Irish government is a
Habitats Directive was transposed into Irish law by:
The EC (Natural Habitats) Regulations 1997. This was the principal
legislation transposing the
Habitats Directive and upgraded the
protection of the Kerry slug's habitat by the designation of Special
Areas of Conservation (as listed in the distribution section above).
Adapting existing legislation. The
Kerry slug has been protected since
1990 under the Irish Wildlife Act of 1976; it was added to the list of
protected species by
Statutory Instrument 112/1990, and was the only
gastropod so protected. The treatment of the Kerry
been cited in the media as an example of hyperprotectionism
(specifically, in the context of delays in the construction of a
proposed by-pass in County Cork). However, The Wildlife Act does
not protect the slug from authorised or unauthorised indirect damage,
but only from wilful direct damage such as collecting.
The Irish National Parks and Wildlife Service published a Species
Action Plan for the
Kerry slug in January 2008. Efforts were
made to protect the slug from indirect damage arising, for example,
from commercial forestry. However, following a legal challenge to
Ireland's transposition and implementation of the Habitats Directive,
the Action Plan was superseded in May 2010 by a Threat Response Plan.
The Threat Response Plan addressed issues which arose when the
European Court of Justice
European Court of Justice held that
Ireland was not protecting the
Kerry slug with the strictness that the directive required in respect
of a species listed in annex 4.
In a report to the
European Commission covering 1988–2007, the
conservation status of the species in
Ireland was declared "favourable
(FV)" in all evaluated criteria (range, population, habitat and future
prospects). However, the validity of this assessment was put
into question by the
European Court of Justice
European Court of Justice ruling discussed above,
which held that
Ireland was not monitoring the slug properly.
The need to improve monitoring was discussed by the NPWS Threat
Response Plan of 2010, which recognised that population statistics
were still deficient, particularly outside the SACs. As the Threat
Response Plan noted, species monitoring is a process in which
distribution and status of the subject are evaluated systematically
over time. Under this definition no monitoring of the Kerry
yet been undertaken in
Ireland as of May 2010. In order to take
matters forward, the Kerry
Slug Survey of Ireland, a collaboration
between the National Parks and Wildlife Service and the Applied
Ecology Unit at the National University of Ireland, Galway, researched
a "suitable monitoring protocol" for the species. The Kerry
Slug Survey's investigations resulted in the publication of a guide to
the population dynamics of the Kerry slug; this guide was published as
part of the Irish Wildlife Manual series in 2011.
Since 1990, the species has been successfully bred in captivity. The
Wildfowl & Wetlands Trust, a British conservation organisation,
operates a captive breeding programme in terraria at its "Endangered
Species Breeding Unit". The project is located not within the species'
normal range, but in England at the Martin Mere Wetland Centre.
During the 1990s, slugs from the breeding programme were given out to
a number of different zoos and individuals in order to set up their
own breeding programmes, but unfortunately only a very few of those
breeding groups survived.
This article incorporates public domain text from Taylor (1907).
^ a b "
Geomalacus maculosus". 2006
IUCN Red List
IUCN Red List of Threatened
Species. Retrieved 18 July 2007. External link in work= (help)
^ a b Allman, G. J. (1843). "On a new genus of terrestrial
gasteropod". The Athenaeum. London (829): 851.
^ a b Simroth, H. (1894). "Beiträge zur Kenntniss der portugiesischen
und der ostafrikanischen Nacktschnecken-Fauna". Abhandlungen der
Senckenbergischen Naturforschenden Gesellschaft (in German). Frankfurt
am Main. 18 (3): 289–307, table 1, figure 1, table 2, figure
^ Castro, J. da Silva (1873). "Mollusques terrestres et fluviatiles du
Portugal. Espèces nouvelles ou peu connues". Jornal de sciencias
mathematicas, physicas, e naturaes (in French). Lisboa. 4:
Geomalacus maculosus General Information". EUNIS biodiversity
European Environment Agency
European Environment Agency (EEA). Retrieved 27 June
^ Simpson, D. P. (1979). Cassell's Latin Dictionary (5 ed.). London:
Cassell Ltd. ISBN 0-304-52257-0.
^ Wade, C. M., Mordan, P. B. & Clarke, B. (2001). "A phylogeny of
the land snails (Gastropoda: Pulmonata)". Proceedings of the Royal
Society B: Biological Sciences. 268 (1465): 413–422.
doi:10.1098/rspb.2000.1372. PMC 1088622 .
PMID 11270439. CS1 maint: Multiple names: authors list
^ a b c d e f g h i j k l m n o . Conservation Status Assessment
Report. National Parks & Wildlife Service, Department of the
Environment, Heritage and Local Government, Ireland. February
2008. Missing or empty title= (help); contribution= ignored
(help) 9 pp.
^ a b Kerney, M. P; Cameron, A. D.; Jungbluth, J. H. (1983). Die
Landschnecken Nord- und Mitteleuropas (in German). Hamburg and Berlin:
Verlag Paul Parey. p. 138. ISBN 3-490-17918-8.
^ a b O'Hanlon, A.; Feeney, K.; Dockery, P.; Gormally, M. J.
(2017-07-10). "Quantifying phenotype-environment matching in the
protected Kerry spotted slug (Mollusca: Gastropoda) using digital
photography: exposure to UV radiation determines cryptic colour
morphs". Frontiers in Zoology. doi:10.1186/s12983-017-0218-9.
^ a b c d e f g h i j k l m n o p q r s t u v w x Taylor, J. W.
(1907). Monograph of the land and freshwater Mollusca of the British
Isles. Testacellidae. Limacidae. Arionidae. pt 8–14. Leeds: Taylor
brothers. pp. 253–259.
^ a b Scharff, R. F. (1891). The slugs of Ireland. The Scientific
Transactions of the Royal Dublin Society, volume IV., series II.
Dublin, Royal Dublin Society; London, Williams & Norgate.
513–563. Cited pages: 551–556.
^ a b c d e f g h i j k l m n Platts, E. A.; Speight, M. C. D. (1988).
"The taxonomy and distribution of the
Allman, 1843 (Mollusca: Arionidae) with a discussion of its status as
a threatened species". Irish Naturalists' Journal. 22 (10):
^ a b Pilsbry H. A. (1898). "Phylogeny of the genera of Arionidae".
Proceedings of the Malacological Society of London 3: 94-104.
^ a b c Godwin-Austen, H. H. (1882). Land and freshwater mollusca of
India, including South Arabia, Baluchistan, Afghanistan, Kashmir,
Nepal, Burma, Pegu, Tenasserim, Malaya Peninsula, Ceylon and other
islands of the Indian Ocean; Supplementary to Masers Theobald and
Hanley's Conchologica Indica. Plates to Volume I. Taylor and Francis,
London. Plate XII, figure 5.
^ (in German) Simroth, H. (1891). "Die nacktschnecken der
portugiesisch-azorischen fauna in ihrem Verhältnis zu denen der
paläarktischen region überhaupt". Nova Acta Academiae Caesareae
Leopoldino-Carolinae Germanicae Naturae Curiosorum 56(1): 201–424,
Tab. IX-XVIII. Halle.
Geomalacus maculosus is on page 351–355.
^ (in French) Germain L. (1930). Mollusques terrestres et fluviatiles.
Première partie. Faune Fr., lechevalier, Paris, 21: 477 pp.
^ Quick H. E. (1960). "British slugs (Pulmonata; Testacellidae,
Arionidae, Limacidae". Bulletin of the British Museum (Natural
History). Zoology 6(3): 103-226.
^ "Family summary for Arionidae". AnimalBase, last change 12-06-2009,
accessed 4 August 2010.
^ a b c d e f "Plano Sectorial da Rede Natura 2000. "Fauna,
Invertebrados"" (PDF) (in Portuguese). Portugal: Instituto de
Conservação da Natureza e da Biodiversidade. 2006. Archived from the
original (PDF) on 26 December 2009. Retrieved 25 September 2009.
^ a b Viney, Michael (May 5, 2010). "Problems with plan for protection
of slugs". Irish Times. Retrieved May 2, 2012.
^ Mascheretti, S.; Rogatcheva, M.B.; Gündüz, İ.; Fredga, K.;
Searle, J.B. (2003). "How did pygmy shrews colonize Ireland? Clues
from a phylogenetic analysis of mitochondrial cytochrome b sequences".
Proceedings of the Royal Society B. 270: 1593–1599.
doi:10.1098/rspb.2003.2406. PMC 1691416 .
^ Reich, I.; Gormally, M.; Allcock, A.L.; Mc Donnell, R.; Castillejo,
J.; Iglesias, J.; Quinteiro, J; Smith, C.J. (2015). "Genetic study
reveals close link between Irish and Northern Spanish specimens of the
protected Lusitanian slug
Geomalacus maculosus". Biological Journal of
the Linnean Society. 116: 156–168. doi:10.1111/bij.12568.
^ Genetic study reveals close link between Irish and Northern Spanish
specimens of the protected Lusitanian slug
Geomalacus maculosus. 2015
The Linnean Society of London, Biological Journal of the Linnean
^ a b c d e f g h i j k l m
Species Action Plan. Kerry Slug.
Geomalacus maculosus (PDF). Ireland: National Parks & Wildlife
Service, Department of the Environment, Heritage and Local Government,
Ireland. January 2008. Archived from the original (PDF) on
2007-12-18. 9 pp.
^ Kearney, Jon (2010). "
Kerry slug (
Geomalacus maculosus Allman 1843)
recorded at Lettercraffroe, Co. Galway". Irish Naturalists Journal.
^ a b c
Geomalacus maculosus. EUNIS (European Nature Information
System), European Topic Centre on Biological Diversity, European
Environment Agency. Retrieved 2017-06-17.
^ a b Ketch, Catherine (2012), Kerry
Slug researcher visits Baile
Bhúirne and Beara, The Corkman
^ a b c Threat Response Plan, Ireland: National Parks & Wildlife
Service. Retrieved 24 June 2012
^ Castillejo, J. (1998). Guia de las babosas Ibericas (in Spanish).
Santiago de Compostela: Real Academia de Ciencias. 154 pp.
^ a b c d Castillejo, J.; Iglesias, J. (2007).
maculosus Allman, 1843. Libro Rojo de los Invertebrados de España
(PDF) (in Spanish). pp. 351–352.
^ Sierra de los Ancares, Urugallo cantábrico website (LIFE Programme:
^ "Ancares (ES0000374)". EEA. Retrieved 21 July 2016.
^ "Ancares-Courel (ES1120001)". EEA. Retrieved 22 July 2016.
^ a b c d e Ramos, M. A. (1998). "Implementing the habitats directive
for mollusc species in Spain". Journal of Conchology. Molluscan
Conservation: A Strategy for the 21st Century,
^ a b c d e f g h i Wiesniewski, P. J. (2000). "Husbandry and breeding
of Kerry spotted slug". International Zoo Yearbook. 37 (1): 319–321.
doi:10.1111/j.1748-1090.2000.tb00736.x. (subscription required)
^ Rodriguez,, T.; Ondina, P.; Outeiro, A.; Castillejo, J. (1993).
"Slugs of Portugal. III. Revision of the genus
Geomalacus Allman, 1843
(Gastropoda:Pulmonata: Arionidae)" (PDF). Veliger. 36 (2): 145–159.
Retrieved 7 March 2016.
^ Rogers, T. (1900). "The eggs of the Kerry
Allman". Irish Naturalist. 9: 168–170, plate 5.
^ a b Giordani I.; Hynes T.; Reich I.; Mc Donnell R. J.; Gormally M.
J. (2014). "
Tetanocera elata (Diptera: Sciomyzidae) Larvae Feed on
Geomalacus maculosus (Gastropoda: Arionidae):
First Record of Predation". Journal of Insect Behavior. 27 (5):
^ a b . Conservation Status Assessment Report. National Parks &
Wildlife Service, Department of the Environment, Heritage and Local
Government, Ireland. 25 February 2008. Missing or empty title=
(help); contribution= ignored (help)
^ a b "Checklist of protected & rare species in Ireland" (PDF).
National Parks & Wildlife Service, Department of the Environment,
Heritage and Local Government, Ireland. 7 January 2009. [dead
link] 15 pp., cited page: p. 12.
^ Eionet (European Environment Information and Observation Network),
European Topic Centre on Biological Diversity. "
Retrieved 18 August 2009.
^ SI 94/1997 as amended by EC (Natural Habitats) (Amendment)
Regulations SI 233/1998 and SI 378/2005.
^ "Wildlife Act, 1976 (Protection of Wild Animals) Regulations, 1990".
Retrieved August 30, 2012.
^ "By the Time We've Saved the Slugs, the Snails and Those Viking
Graves, Who Will Save the Commuter?".
Daily Mail (London).
McClatchy-Tribune Information Services. 2007. Retrieved July 21, 2014
HighBeam Research (subscription required)
^ Bruce, Helen (January 2008). "On the wild frontier; (1) Under
threat: The otter is a perennial favourite for children and nature
enthusiasts, with its expressive features, dog-like playfulness, grace
in the water and furry coat (2) Image problem: Not as cuddly as the
otter but the Kerry
Slug is still in need of our help". Daily Mail
(London). McClatchy-Tribune Information Services. HighBeam Research
(subscription required). Retrieved August 30, 2012.
Slug and Otter Guidelines". The Forest Service, Department of
Agriculture, Fisheries and Food. 2009. Retrieved October 9,
^ Commission v
Ireland C-183/05. (The court case did not just involve
the Kerry slug, but considered wider transposition failures by
Slug Survey of
Ireland (Official Website) Retrieved 3 July
^ Mc Donnell, R.J. and Gormley M.J. (2011). Distribution and
population dynamics of the Kerry Slug, Irish Wildlife Manual No 54,
National Parks and Wildlife Service, Department of Arts, Heritage and
the Gaeltacht, Dublin
Allman, G. J. (1844). "On a new genus of terrestrial gastropod".
Report of the
British Association for the Advancement of Science
British Association for the Advancement of Science 1843:
Allman, G. J. (1846). "Description of a new genus of pulmonary
Annals and Magazine of Natural History
Annals and Magazine of Natural History 17: 297–299,
Boycott A. E., Oldham C. (1930). "The food of
Journal of Conchology. 19: 36.
Oldham, C. (1942). "Notes on Geomaculus maculosus". Proceedings of the
Malacological Society of London 25.
Heynemann, D. F. (1873). "On the French species of the genus
Geomalacus". Annals and Magazine of Natural History, pages 271–275.
(in German) Heynemann, D. F. (1869). "Zur Kenntniss von Geomalacus".
Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft, pages
(in German) Heynemann, D. F. (1871). "
Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft 3(1):
(in German) Heynemann, D. F. (1873). "Ueber Geomalacus".
Malakozoologische Blätter xxi: 25–36, table 1, fig. 1-6.
Moorkens, E. A. (2006). "Irish non-marine molluscs – an evaluation
of species threat status". Bulletin of the Irish Biogeographical
Society 30: 348–371. OCLC 265510707.
Scharff, R. F. (1892). "Land and freshwater shells peculiar to the
British Isles". Nature, 46(1178): 173. doi:10.1038/046173d0
Scharff, R. F. (1893). "Note on the geographical distribution of
Geomalacus maculosus Allman, in Ireland". Proceedings of the
Malacological Society of London, volume I, 1893–1895, 17–18.
Wikimedia Commons has media related to
Geomalacus maculosus at
Animalbase taxonomy,short description,
distribution, biology,status (threats), images
Bridges & Species: Post-Glacial Colonisation
A photograph of a live individual
Fauna Europaea: 421755