Leaf Snails (Hygromiidae) Part 2

Hair snails and leaf snails

Leaf Snails (Hygromiidae) Part 1

Explanation of shell characters for identification.

Explanatory note: The genus name Trichia Hartmann 1840, in use so far, cannot be employed any longer, because this name is previously occupied (preoccupied) by a genus of slime mold (Myxomycetes), Trichia Haller 1768. The genus name is male, which is why the species name must be adjusted accordingly - Trichia villosa consequently has to be called Trochulus villosus.

Common Hair Snail, Trochulus hispidus (Linnaeus 1758)


Common hair snail (Trochulus hispidus).
Picture: Michal Maňas (Source).
 

Description: The common hair snail has got a flat shell with a slightly ascending flatly conical spire. The shell surface is finely striped and covered with short and close hairs. The shell mouth is flattened at the bottom and has got a swollen apertural lip. The umbilicus is open and wide.

Dimensions: W: 5 - 12 mm; H: 5 - 6 mm; N: 6 - 7. (Abbreviations).

Habitat and Distribution: The common hair snail appears in bright forests, on bushes and in cultural habitats, preferably on nettle plants.

The species is distributed over all of Europe except the Southern peninsulas.

Remark: The hairs earning this species' name are also found on juvenile cheese snails (Helicodonta). According to a paper by Markus Pfenninger et al.: "Why snails have hairs", they help the snails to keep their footing on wet leaves of their food plants.

Furry Hair Snail - Trochulus villosus (Draparnaud 1805)

 
Furry hair snail (Trochulus villosus) from canton St. Gallen,
Switzerland. Picture: Roland Bodenmann.

Description: The furry hair snail has a light yellowish grey to reddish brown shell, whose surface is coarsely striated. In the living state the shell is grown with hairs about 1.5 mm long, which, though, are lost when the snail dies and which might even lack completely. The shell tip (apex) is blunt and the shell has a flattened upper side, but the whorls are rounded at the sides. The last whorl descends slightly before reaching the aperture. The shell mouth is rounded, the aperture lip only weakly developed. The navel (umbilicus) is wide and deep, it takes about one fifth of the shell diameter.


Magnified view of the shell of a living furry hair snail. Especial-
ly well visible: The striate sculpture of the shell and the long
hair (1.5 mm). Picture: Roland Bodenmann.
 

The snail itself is light brown with darker greyish tentacles.

Dimensions: H: 6 - 8 mm; W: 11 - 14 mm; N: 5 - 6. (Abbreviations).

Habitat and Distribution: The furry hair snail lives in shady and humid places, mostly in forests in higher altitudes. This leaf snail species needs much humidity. Only in areas with much precipitation it also appears in open habitats, such as alpine meadows.

Trochulus villosus can be found in the north-western and western Alps, as well as in south-western Germany. Along the rivers it also appears further north of the Alps, such as near the river Rhine until Mainz, the river Danube until Dillingen. In the Alps, the furry hair snail usually lives in altitudes between 500 and 2000 m MSL, in Switzerland it climbs to altitudes of up to 2400 m MSL.

Threat Situation: While the furry hair snail in Germany generally is classified as near threatened, in Rhineland-Palatinate and Lower-Saxony near the limits of its distribution area, it is classified as vulnerable (VU) (see also: IUCN Threat Categories).

Systematics: A smaller subspecies (7 - 10 mm diameter on Alpine meadows, compared to 13 - 15 mm in lowland forms) with shorter hair, Trochulus villosus alpicola Eder 1921 was described from the western Alps. An own species, however, it cannot be, as in the western distribution area there are all kinds of intermediate forms. The smaller subspecies displays the same striate surface sculpture and also the genital apparatus shows strong similarity. Besides, Alpine dwarf forms are known from all parts of the Alpine distribution area of Trochulus villosus.

Mollbase: Trichia (Trichia) villosa (Zottige Haarschnecke). (In German)
Francisco Welter-Schultes: Trochulus villosus species homepage.

Toothless Hair Snail - Petasina edentula (Draparnaud 1805)

Gemeine Haarschnecke (Trichia hispida)
Toothless hair snail (Petasina edentula).
  Gemeine Haarschnecke (Trochulus hispidus) und Strauchschnecke (Fruticicola fruticum)
With a bush snail (Fruticicola fruticum). [RN]
 

Description: The toothless hair snail has a horn coloured to reddish brown shell with a finely striated surface. The shell form varies between flat and conical. In juveniles, the shell often is densely grown with hair, sometimes falling out in adult shells. The whorls are densely coiled, the last whorl is slightly more keeled. The small, sickle-shaped aperture on the inside shows a whitish lip, which at its base by be thickened, but does not display a tooth. The shell navel (umbilicus) is very narrow.

Petasina edentula is smaller than the similar Petasina unidentata, it is different from that species by a more distinct keel, a narrower aperture and the missing apertural tooth

The snail itself is light brown, with a dark head and dark tentacles.

Bush snails (Bradybaenidae): Distantly related to leaf snails, with them and the Helicid snails, the bush snails are joined to form the Helicoidea superfamily.

Dimensions: H: 4.5 - 5.5 mm; W: 7 - 8 mm; N: 6 - 6. (Abbreviations).

Habitat and Distribution: The toothless hair snail lives between herbs and under leaves and stones in humid mountain forests on calcareous ground. Usually Petasina edentula does not appear beyond the tree line, but sometimes it is also found in open forests and on stony alpine pastures. Petasina edentula lives in altitudes between 300 and 2300 m MSL.

The species' distribution area stretches from the western Alps north of the river Durance and the French Jura until the central Swabian Alb, the northern Alps and continues in a disperse manner through the eastern Alps south towards the Julian Alps. The toothless hair snail hardly appears in the Alpine foot hills.

Threat Situation: In Germany, the species is classified as vulnerable, in Austria as near threatened (see also: IUCN Threat Categories).

Francisco Welter-Schultes: Trochulus edentulus species homepage.
Fauna Europaea: Trichia (Edentiella) edentula.

Large Leaf Snail, Euomphalia strigella (Draparnaud 1801)

 
Large leaf snail (Euomphalia strigella).
 
Pictures: Alexander Mrkvicka, Vienna (mrkvicka.at).

Euomphalia strigella. Picture: Helmut Nisters.
 

Description: The large leaf snail has a depressed conical shell, whose colour can range from yellowish grey to horn-like brown. The shell has a finely ribbed surface and can be grown with hairs in juvenile specimens. The whorls are convex, the apertural rim is widened with a whitish lip. The umbilicus is wide, taking about one fifth of the shell diameter (more than in Fruticicola fruticum and distinctly more than e. g. in Monacha cantiana).

Literally, this snail's genus name means "with a fine navel".

The snail's body is yellowish grey to reddish brown with little black spots, which can be seen through the shell wall. The tentacles are darker and greyish. The snail crawls slowly, is easily frightened and then secretes lots of slime.

Dimensions: W: 13 - 18 mm; H: 8 - 12 mm (Abbreviations).

Habitat and Distribution: The large leaf snail lives mainly on the ground in open forests, bushes and on half-dry meadows. Its distribution area covers East and Central Europe, from southern Scandinavia and northern Russia through Central France as far west as the Pyrenees, in the south to northern Italy. In Switzerland and Bulgaria this species is found in altitudes of up to 1600 m MSL.

Euomphalia strigella is a potential intermediate host to the lesser liver fluke (Dicrocoelium lanceolatum).

Threat Situation: The large leaf snail in parts of its distribution area is threatened by the destruction of its habitats. So for example in Upper Austria and in Salzburg it is critically endangered (CR), in Lower Saxony and in Rhineland-Palatinate it is vulnerable (VU), in Bavaria it is in decline and in the rest of Germany, Austria and in Switzerland, it has been classified as near threatened ( IUCN Threat Categories).

Links

Girdled Snail, Hygromia cinctella (Draparnaud 1801)


Girdled snail (Hygromia cinctella) - Switzerland.
Picture: Stefan Haller, (schneckenfoto.ch).
 
Girdled snail (Hygromia cinctella) - Vienna.
Picture: Alexander Mrkvicka, Vienna (mrkvicka.at).
 

Description: The shell of Hygromia cinctella has thin walls and a low cone form. It is of a whitish grey to horn brown colour and its surface displays dissolving stripes. The last whorl displays a distinct keel with a light keel band. The aperture rim is hardly widened, the navel (umbilicus) is very narrow and almost entirely covered by the columellar part of the aperture lip. The snail itself is slender, light yellowish grey and has a dark head and tentacles.

Dimensions: W: 10 - 12 mm; H: 6 - 7 mm; N: 5 - 6. (Abbreviations).

Habitat and Distribution: The girdled snail live in low bushes and in fresh herb vegetation, often also near streams. In Switzerland it almost exclusively lives in anthropogenic habitats, in gardens on herbs and bushes, more rarely in natural forests, in altitudes of up to 900 m MSL. In England, the snail can be found in the grass, between nettles, ivy, umbellifers and similar plants at the wayside.

The species' distribution area stretches from southern France to south-western Switzerland, Italy and north-western Yugoslavia. The girdled snail has been introduced to England (Devon and Worcestershire), Austria (Vienna) and Hungary (Budapest), as well as to the USA (Georgia).

Links

Shadow Snail, Urticicola umbrosus (C.Pfeiffer 1801)


Shadow snail (Urticicola umbrosus). Picture: Robert Nordsieck.
 

Description: The shadow snail has a strongly depressed thin-walled shell, which is finely striated, sparsely grown with hair and characteristically grained, especially in a weathered state (visible with a magnifying glass with six times magnification, an important character of difference to other species). The shell has a pale yellowish grey to reddish brown colour, with the mantle pattern often visible through the thin shell wall.

 
Urticicola umbrosus, view of the navel (umbilicus).
Picture: Robert Nordsieck.

The shell lip is only weakly developed, the navel (umbilicus) is wide and perspectivic.

Literally, this species genus name Urticicola means "living on nettles".

Dimensions: W: 12 mm; H: 6 mm; N: 5. (Abbreviations).

Habitat and Distribution: The shadow snail lives on the ground, under dead leaves in the herb and bush vegetation of humid forests. Its distribution area stretches from western Ukraine over the northern Carpathians and the Polish Jura as far west as the eastern German low mountain ridges, the eastern Alps and their foot hills. The western limit of distribution goes from the eastern Franconian Jura, Upper Swabia, the Tyrolean Inn valley in the south to Bosnia.

Links

Ciliate snail - Ciliella ciliata (Hartmann 1821)


Ciliate snail (Ciliella ciliata).
Picture: Stefan Haller, (schneckenfoto.ch).
 

Description: The ciliate snail has got a brownish flattened shell with a conical upper side and a rounded lower side. On the periphery, the whorls are sharply keeled. The apertural lip is simple, sharp and folded back. The shell navel (umbilicus) is narrow, but open and partially covered by the apertural lip.

Especially conspicuous are the periostracum spikes running along the snail's keel, giving it the appearance of a spiny acanthinula (Acanthinula aculeata), though that snail species, of course, is noticeably smaller.

 
Ciliella ciliata. Picture: Helmut Nisters.

Dimensions: H: 4 - 6 mm; W: 9 - 12 mm.

Habitat and Distribution: Ciliate snails live on humid grassy slopes, along streams and on slopes in the mountains, also on pastures and in the herbal vegetation of forests. Rarely the species can also be found in gardens and parks. In the Alps, the snail lives in altitudes of up to 2100 m MSL.

The distribution area of Ciliella ciliata covers the western and southern Alps, in the South as far as the Tuscan Apennine, in the East as far as Tagliamento river in Friuli and southern Carinthia. Isolated populations of the species also have been found in the eastern Pyrenees.

Links

Francisco Welter-Schultes: Ciliella ciliata species homepage.

Sources

Falkner, Fechter: "Weichtiere" (1990). (In German)
Kerney, Cameron: "Land Snails of Britain and North-West Europe" (1979)


With pictures by Stefan Haller:
http://www.schneckenfoto.ch.