Dagger Snails

Gastrodontidae Tryon, 1866
Diese Seite auf Deutsch!  
Diese Seite auf Deutsch!  
 
Gloss Snails (Zonitidae etc.) Dagger Snails (Gastrodontidae) Gloss Snails (Oxychilidae) Daudebardias (Daudebardiinae)

Introduction

 
Gloss Snail (Aegopinella nitens) attacking a leaf snail (Peta-
sina unidentata). Photo: © Stefan Haller, (schneckenfoto.ch).
The genus Aegopinella and similar groups, like for example Retinella, are small snail species with a glossy and translucent, usually wide-mouthed shell, that usually live as predators. Only some of those species can be identified clearly by the morphology of their shell. In others, the finding location and the local habitat may be indispensable, as well as, as a last resort, an anatomical examination of  the genital apparatus.

While those and similar genera in earlier times were counted among the Zonitidae family, today their systematical status is unclear to some degree, depending on which systematical source is consulted. MolluscaBase puts Aegopinella and other general in the family of the dagger snails (Gastrodontidae), a part of which, for example, is also the Zonitoides genus. V. Wiese, in the latest edition of his book "Die Landschnecken Deutschlands" ([The Land Snails of Germany]) follows this opinion, while the Naturportal Südwest, an internet page of the Stuttgart Natural History Museum, leaves Aegopinella and Retinella in the family Oxychilidae.

On the present page, the genera Aegopinella and Retinella therefore are placed in the dagger snail family, together with the Zonitoides genus.

Links and Literature

Dagger Snails - Gastrodontidae Tryon, 1866

Wide Mouthed Gloss Snail - Aegopinella nitens (Michaud 1831)

Wide-Mothed Gloss Snail (Aegopinella nitens)
Wide-Mothed Gloss Snail (Aegopinella nitens).
Photo: © Stefan Haller, (schneckenfoto.ch).		  
 
Wide-Mouthed Gloss Snail (Aegopinella ni-
tens). Photo: Helmut Nisters
Description: The Wide-Mouthed Gloss Snail has a light brownish horn coloured shell. The shell spire is flatly conical, the shell tip (apex) is not convex (difference to the slightly smaller Aegopinella nitidula). The lateral line of the slightly rounded whorls is almost flat.

In front of the aperture, the latest whorl noticeably widens (hence the name), so that it becomes almost three times as wide as the penultimate whorl. It is flattened and not descending at the aperture. The aperture itself only is a little oblique. The shell navel (umbilicus) is wide and shaped like a funnel.

Dimensions: H: 4 - 5.5 mm; W: 8 - 11 mm (in the Alps up to 14 mm); N: 4 - 4½. Information: Abbreviations

Habitat and Distribution: Wide-Mouthed Gloss Snails live in the leaf litter and beloe stomes in humid forests, as well in the valleys as on the mountain side. Aegopinella nitens prefers ground rich in limestone, especially in submontane and montane higher locations. Also, Aegopinella nitens is a hygrophilous species fond of humidity, which in Switzerland avoids sonny climates like in the Lower Valais and the Engadin.

The Wide-Mothed Gloss Snail is present in the Alps, the western Carpathians, and the low mountain ranges of Germany and Czechia. The northernmost finding location is near Bad Pyrmont in southern Lower Saxony. In the Alps, Aegopinella nitens is found in altitudes of up to 2300 m MSL, but rarely occurs above 1500 m MSL.

 

Threat Situation: In Lower Saxony, the Wide-Mothed Gloss Snail is considered as critically endangered ( see IUCN Threat Categories).

Links

Reddish Gloss Snail - Aegopinella nitidula (Draparnaud 1805)


Reddish Gloss Snail (Aegopinella nitidula): Embourg, Chaud-
fontaine, Belgien. Photo: Gilles San Martin. (iNaturalist). 		 
Description: Like its name already states, the Reddish Gloss Snail has a reddish horn coloured shell, which near the umbilicus turns milky white. The shell whorls regularly grow in size, are rounded and the shell tip (apex) is elevated in a convex manner (contrary to Aegopinella nitens). The apertural whorl is slightly extended, the shell navel (umbilicus) is actually wide.

Dimensions: H: 4 - 6 mm; W: 6 - 11; N: 3.5 - 4.5. Information: Abbreviations

 
Reddish Gloss Snail (Aegopinella nitidula):
Garrigill Garden, Cumbria, England, GB.
Photo: Alex Playford (iNaturalist). 
Habitat and Distribution: The Reddish Gloss Snail lives in the ground litter of many protected habitats, in deciduous and coniferous forests, at the foot of rocks and stone walls, on humid meadows, in gardens and aside paths. Aegopinella nitidula is generally rather insensitive towards human influence.

It mainly feeds on decaying plant matter, but also partly is a predator: It hunts smaller snails (up to a diameter of 4.5 mm) and slugs (up to a length of 17 mm). It also likes to feed on earthworms and other kinds of worms.

The species' distribution area spread from the Azores over northern Spain, the British Isles and France as far a northern Germany, northern Poland and the South of Scandinavia. South of the North German Plain, the species occurs as far as Upper Swabia, northern Bavaria and Bohemia in a dispersed manner.

In North America, the species has been introduced by man, for example in British Columbia (Canada).

Links

Literature

Lesser Gloss Snail - Aegopinella pura (Alder 1830)


Lesser Gloss Snail (Aegopinella pura).
Photo: © Stefan Haller, (schneckenfoto.ch).		  
Description: The Lesser Gloss Snail has a thin-walled, almost translucent, slightly glossy shell, whose surface is covered in a network of fine longitudinal lines, which are crossed by irregular transversal lines (best seen under a mikroscope with a magnification of 35 - 40×). The shell whorls are arched, the spire is flatly conical. The last whorl near the aperture is little extended and does not descends near the aperture. On the upper side, it is flattened. The navel (umbilicus) is widened and funnel-shaped (almost ¼ of the shell diameter) and slightly off centre.

Dimensions: B: 3.5 - 5.0 mm; H: 2.0 - 2.7 mm; N: 3¾ - 4¼. Information: Abbreviations

Habitats and Distribution: The Lesser Gloss Snail lives in the leaf litter. It is found around plants and under deadwood in moderately dry forests on mountains and in plains, especially on ground rich in limestone. Mating takes place in spring, the adult snails die after laying eggs. The juveniles mature after two years.

 Schwer, H. (1994). Populationsbiologie kleiner laubstreubewohnender Landgastopoden: Lebenszyklus und saisonale Abundanzdynamik am Beispiel von Aegopinella pura (Alder 1830). - Mitt. Dt. Mal. Ges. 54: 13-14.

The distribution area of the Lesser Gloss Snail spreads from Iceland over Central Europe as far as northern Iran; in Scandinavia it is mainly found at the coast. Aegopinella pura is present in mainland Italy and Sardinia, but absent in Sicily. It is also absent in southern Turkey. In the entire Alpine region, it is present, including the foothill regions, as well as in the Carpathians and their eastern spurs and foothills. In Switzerland, the Lesser Gloss Snail is found in altitudes up to 2300 m MSL.

Links

South-Alpine Gloss Snail - Retinella hiulca (Albers 1850)

 
Südalpen-Glanzschnecke (Retinella hiulca).
Bild: © Stefan Haller, (schneckenfoto.ch).

South-Alpine Gloss Snails (Retinella hiulca) mating.
Photo: © Stefan Haller, (schneckenfoto.ch).		  
Description: The South-Alpine Gloss Snail is larger than the domestic Aegopinella species. The shell spire is relatively high, the navel is narrow. The last whorl is extended and descended, the whorls are rounded (cenvex).

The snail resembles Aegopinella ressmanni, a larger species of Aegopinella, but it is even larger. The shell is glossy and does not display clear growth lines, as little as the netted sculpture that is found in the Lesser Gloss Snail (Aegopinella pura) findet.

Dimensions: W: 10 - 14 mm; H: 6 - 7 mm; N: 4 - 4½. Information: Abbreviations

Habitat and Distribution: Retinella hiulca also is an inhabitant of the leaf litter layer. The species is present on ground rich in limestone, in forests, on shady hillsides with bush vegetation, vineyards in between stones, as well as under stones in the vegetation in the waterside area of streams. Contrary to Aegopinella pura, Retinella hiulca only lives in altitudes of up to 1100 m MSL.

Like the name says, the distribution area of the South-Alpine Gloss Snail stretches over the Swiss Southern Alps (Southern Ticino, almost exclusively in the Sottoceneri region; findings in the Sopraceneri most likely are due to introduction by humans) and northern Italy (Lago Maggiore as far as Lake Como and the southern rim of the Lombard Alps).

Links

Dagger Snails - Zonitoides Lehmann, 1862

 
Quick Gloss Snail (Zonitoides arboreus): Ontario,
Canada. Photo: Andrew Jackson (iNaturalist). 
A special character of the dagger snails (Zonitoides) is a "dart-like, calcareous stimulating organ, also referred to as a Love Dagger" (Falkner, 1990, p. 170), of which the snail family derives their vernacular name, as well as the scientific name of their family. The dagger snails the dart sac with this "love dagger" is located lower on the penis, meaning in the male part of the genital apparatus, contrary to most of the other snail groups, in which the dart sac, as well as the love dart itself, have evolved in the female part of the genital apparatus! (see also "The Love Dart").

Most dagger snails with a holarctiv distribution pattern (see Faunal Provinces), are small snail between several millimetres and about a centimetre in size. In North America, several species are present, as are in Central America, the Canary Islands and on Madeira. In Europe, there are three domestic species known, as is one greenhouse species: Zonitoides arboreus (Photo on the right). The snails usually live near water.

Links

Literature

Black Gloss Snail - Zonitoides nitidus (O. F. Müller 1774)


Black Gloss Snail (Zonitoides nitidus): Gmunden, Upper
Austria. Photo: Jindřich Soukup/a> (iNaturalist).		  
Beschreibung: The Black Gloss Snail has a reddish brown shell with transverse growth stripes. The shell navel (umbilicus) is very wide and almost take a quarter of the shell's overall diameter. The snail's soft body itself is very dark coloured. The characteristic orange pallial gland is visible through the shell wall. Juvenile animals are qhitish grey with translucent light brown shells.

Dimensions: H: 3.5 - 4 mm; W: 6 - 7 mm; N: 4¾ - 5. Information: Abbreviations

 
Black Gloss Snail (Zonitoides nitidus) from the Canton St. Gal-
len (Switzerland). Photo: © Stefan Haller (schneckenfoto.ch).
Habitat and Distribution: The Black Gloss Snail is a snail species partial to humidity, which usually is found next tp water, on humid meadows and in riparian forests, often also on plants standing in the water. Zonitoides nitidus also settles habitats formed by man, such as abandoned and flooded stone quarries. In spite of its similarity to gloss snails (Zonitidae etc.), Zonitoides nitidus is a herbivore. The snails feed on decaying leaves, mushrooms and toadstools, roots and fruit, preferring wet leaves. On mushrooms, the snail leaves characteristic feeding traces, eating deep holes into the fruiting body, into which is can disappear including the entire shell.

The Black Gloss Snail is distributed holarctically and found in almost all of Europe, with the exception of the deep South. The species is rare in northern Greece and the Scottish and North English Highlands. It is, however, absent in northern Scotland, as well as the nearby islands. The species was introduced on the island of Menorca.

Threat Situation: In some parts of Great Britain, the Black Gloss Snail is declining because of the draining of its habitats

Links

Quick Gloss Snail - Zonitoides arboreus (Say 1816)


Quick Gloss Snail (Zonitoides arboreus) from Iowa, USA.
Photo: Harlan Ratcliff.		  
Description: The Quick Gloss Snail (In Europe also referred to as Greenhouse Gloss Snail) has a light brown yellowish translucent shell, which is striped lightly and irregularly. The shell whorls sometime ae slightly keeled. The navel (umbilicus) is deep, but much more narrow as in Zonitoides nitidus, only to about one seventh of the shell diameter. The snail's soft body is characteristically bicolour: The back, tentacles and upper flanks are blue grey, the lower flanks and foot sole are light grey.

Dimensions: H: 1.7 - 3 mm; W: 4.5 - 6 mm; N: 4 - 4½. Information: Abbreviations

 
Quick Gloss Snail (Zonitoides arboreus) from Iowa, USA.
Photo: Harlan Ratcliff.
Habitat and Distribution und Verbreitung: The Quick Gloss Snail is found in woody locations (the scientific name means "Tree Gloss Snail") and also in more humid habitats in different altitude zones. Among others, it is also found in cultivated habitats, such as in gardens. Generally, Zonitoides arboreus prefers drier habitats than Zonitoides nitidus. From Montana, the species is reported from an altitude of 1471 m MSL.

In North America, the Quick Gloss Snail is widely distributed: In Canada, it is found from British Columbia in the West as far as Newfoundland in the East, through the USA as far as Mexico and in the South as far as Costa Rica.

In Europe, however, the Quick Gloss Snail is a so-called greenhouse species, usually introduced with imported plants and found near the greenhouses. Especially on orchid plants, the snails are often found and can harm those with not insignificant amounts of feeding damage. The species is known as an introduced species from Iceland and Sweden, Austria and Hungary, Germany and Switzerland, as well as other parts of the world, such as Australia, Kamchatka, Japan, Hawaii, Israel and South Africa.

Escaped specimens sometime also can survive in the wild quite well. Wild living populations in Europe, however, are not well researched. According to more recent reports,wild living populations are known from Sweden (1956, 2003), Hungary (2001), Mecklenburg-Vorpommern in northeastern Germany (2003) and Czechia (2007). Older reports from before 1920 mention Finland, Russia and Ireland.

Links

Literature

 


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

Latest Change: 26.07.2026 (Robert Nordsieck).