Black keel cone
| Black keel cone | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Milax nigricans | ||||||||||||
| ( RA Philippi , 1836) |
The black keel snail ( Milax nigricans ), also black keel snail , is a nudibranch from the family of the keel snails (Milacidae) in the suborder of the land snails (Stylommatophora).
features
The animal is stretched out 5 to 7.5 cm long and about 13 mm wide. The coat is comparatively small and only takes up about 25-30% of the body length (when stretched out). It has shallow pits; between the breathing opening and the keel there are 14 to 15 pits. The back is usually intensely black in color, becoming lighter on the sides. Pale blue-gray or slightly brownish color variants are also less common. The young animals are still yellowish in color. The surface is roughly wrinkled and there are no side ties. The respiratory opening has a weakly colored border. The keel is clearly pronounced, tightly rounded to almost pointed at the top and trimmed at the rear end. The sole is dirty-cream-colored to light-brownish. The mucus is white or colorless.
In the female part of the genital tract, the free fallopian tube (oviduct) is very long and the vagina is distended and very short. The sperm library has a very short, thick stem and a very large, voluminous bladder. The spermatic duct (vas deferens) is short and penetrates centrally into the apex of the thick epiphallus. This decreases somewhat in thickness towards the constricted transition area to the penis. The penis is very short and has a smaller diameter than the penis. The penile retractor muscle starts directly in the constriction. The stimulator is highly conical and almost pointed towards the end. The lower part is covered with numerous papillae, the pointed end is smooth. The atrium is very short and merges into the vagina without any noticeable change in thickness or constriction. The accessory glands are a lumpy mass that merge into 16 to 18, very thin, tubular tubules and terminate in the vagina.
Similar species
The black keel cone cannot be distinguished from the dark keel cone ( Milax gagates ) from the outside . A reliable determination can only be made by examining the genital tract. In the case of the Milax gagates , the stimulator has no papillae at the base; only a few papillae are present at the free end. On average, the black keel cone is slightly larger, the coat is slightly smaller (in relation to the total length), the body is slightly lighter and the sole is monochrome. Milax ater from North Africa has a stimulator without any papillae or has only a few extensions at the free end.
Geographical distribution and habitat
The original distribution area was the western Mediterranean area; on the European side from Malta and Sicily to southeastern Spain, in North Africa from Egypt, and Tunisia to Morocco and the Canary Islands. The species is often brought along with vegetables. It has already been proven in a garden in England and in the field near Munich. A stable colony has been established in the Netherlands since the 1990s. Stable populations are not yet known in Germany.
In Central Europe the species is found almost only in cultivated land, for example in gardens, parks, fields and greenhouses. The animals gather and often hide in large numbers under stones, dead wood and the leaf litter.
Taxonomy
The taxon was established in 1836 by Rudolph Amandus Philippi in the original combination Parmacella nigricans . He attributed the taxon to an AGF Schultz. However, since the description comes from Philippi alone, Philippi is to be assumed as the author. It is now generally accepted as belonging to the genus Milax Gray, 1855. The species has often been confused with the dark keel snail ( Milax gagates ). The literature references on the geographical distribution of this species are therefore often unreliable. A reliable determination of the two types is only possible by examining the stimulator.
Danger
Since the black keel snail is not a native species in Germany, it is not rated in Germany's Red List.
literature
- Rosina Fechter and Gerhard Falkner: molluscs. Mosaik, Munich 1990, ISBN 3-570-03414-3 (= Steinbach's natural guide , volume 10), p. 184.
- Michael P. Kerney, RAD Cameron, Jürgen H. Jungbluth: The land snails of Northern and Central Europe. 384 pp., Paul Parey, Hamburg & Berlin 1983, ISBN 3-490-17918-8 , p. 179.
- Andrzej Wiktor: The slugs of the former Yugoslavia (Gastropoda terrestria nuda - Arionidae, Milacidae, Limacidae, Agriolimacidae). Annales Zoologici 46 (1-2): 1-110, Warsaw 1996
On-line
Individual evidence
- ↑ Francisco W. Welter-Schultes: European non-marine molluscs, a guide for species identification = identification book for European land and freshwater mollusks. A1-A3 S., 679 S., Q1-Q78 S., Göttingen, Planet Poster Ed., 2012 ISBN 3-933922-75-5 , ISBN 978-3-933922-75-5 (p. 439)
- ↑ a b Vollrath Wiese: The land snails of Germany. 352 pp., Quelle & Meyer, Wiebelsheim 2014, ISBN 978-3-494-01551-4 (p. 201)
- ↑ Rudolf Amandus Philippi: Enumeratio molluscorum Siciliæ cum viventium tum in tellure tertiaria fossilium, quae in itinere suo observavit. (Vol. 1). S. I-XIV, 1-267, Schropp, Berolini / Berlin, 1838 Online at Biodiversity Heritage Library , p. 125.
- ↑ MolluscaBase: Milax nigricans (Philippi, 1836)