Institute of Botany
Sect. Plant Ecology
Systematics of land snails
The system of terrestrial gastropods is sometimes arbitrary. Systematic relationships have mainly been reconstructed because of morphological similarity (e.g. subtle structures of shell patterns) and/or because of soft body characteristics (e.g., genitalia and urether). We investigated groups of land snails with rRNA and histone gene sequence analyses, with RAPD fingerprints, and with allozymic signals. Eventually, we found the family-categories Cochlicopidae, Vertiginidae and Valloniidae just as a loose arrangement of morphological similar phenotypes, and even within Vallonia the morphotypes of V. excentrica seem paraphyletic. Our results indicate that some well known snail categories are not really existing as monophyletic units. They are just „smorgasbords“ and „samalgundi“ of unrelated taxa.
To give a deeper insight in the problem of land snail systematics, we analysed the speciation within Cochlicopa. Delimitation of the evolutionary units within this genus has been a controversial issue since decades. Cochlicopa snails are notoriously variable in shell form and in male genitalia structures. The unclear systematics makes the development of conservation strategies difficult. We investigated the phenotypic, molecular and ecological profiles of populations to delimitate the evolutionary units. We conclude that Cochlicopa snails belong to highly self-fertilizing animals. The current species concept for Central Europe categories is as follows:
•Cochlicopa nitens (Gallenstein, 1848): 'good' taxon. Large and bulgy shells; occurs in undisturbed wet lands and calcareous bogs; patchily distributed in central Europe; rare and endangered snail throughout its distribution range. Cochlicopa nitens can be recognized by a combination of habitat characteristics, ITS1-rDNA sequence signals, allozyme patterns and discriminant thresholds of four shell variables.
•The eco-strains of Cochlicopa lubrica (O.F. Müller, 1774): two molecular subgroups predominantly breeding under self-fertilization. The two subgroups evolve through selection-by-habitat (one group prefers moist/shady habitats, the other group is common in dry/exposed habitats); variable in shell size and shell shape; widely distributed throughout Central Europe.
•Cochlicopa lubricella type 1 and C. lubricella type 2 (? Rossmässler, 1834 ?): two independent (paraphyletic) genetic groups, both having small and slender shells. The two groups have not yet been found together within a sampling site. More or less frequent in dry and exposed habitats (limestone rocks, light-radiated forests with calcareous ground, grass land, heath land). The lubricella problem needs to be deeper investigated. One of the two groups seems tightly related to lubrica, hence being a dwarfish and slender form of the latter. Conservation status of both lubricella types is unclear; potentially endangered snails.
I think that the following two species are artificial, and do not exist at all:
Cochlicopa repentina Hudec, 1960: in my opinion C. repentina is not a real taxon; repentinas are just anatomical phenotypes of C. lubrica, e.g. anatomical patterns depend on temperature and/or light-dark environmental conditions
Cochlicopa lohmanderi Waldén, 2001: status unclear; described from southern Sweden, looks at the first glance like a small lubrica type
Note: this taxon-concept of Cochlicopa differs strongly from the “conservative” opinion published by Falkner et al. (2001): Heldia 4: page 31
Korte A & Armbruster GFJ (2003) -- Apomorphic and plesiomorphic ITS-1 rDNA patterns in morphologically similar snails (Stylommatophora: Vallonia), with estimates on divergence time -- Journal of Zoology 260: 275-283
Armbruster G & Bernhard D (2000) -- Taxonomic significance of ribosomal ITS-1 sequence markers in self-fertilizing land snails of Cochlicopa (Stylommatophora, Cochlicopidae) -- Mitteilungen des Museum für Naturkunde Berlin, Zoologische Reihe 76: 11-18
Armbruster G (1997) -- Evaluations of RAPD markers and allozyme patterns: evidence for morphological convergence in the morphotype of Cochlicopa lubricella (Gastropoda: Pulmonata: Cochlicopidae) -- Journal of Molluscan Studies 63: 383-392
Armbruster G (1995) -- Univariate and multivariate analyses of shell variables within the genus Cochlicopa (Gastropoda: Pulmonata: Cochlicopidae) -- Journal of Molluscan Studies 61: 225-235
Armbruster G (1994) -- The taxonomically relevant parts of the male genitalia of Cochlicopa: seasonal variability within two field populations and observations under laboratory conditions (Gastropoda: Pulmonata: Cochlicopidae) -- Malakologische Abhandlungen 17: 47-56
Armbruster G, Schlegel M (1994) -- The land snail species of Cochlicopa (Gastropoda: Pulmonata: Cochlicopidae): presentation of taxon-specific allozyme patterns, and evidence for a high level of self-fertilization -- Journal of Zoological Research and Evolutionary Research 32: 282-296
Armbruster G (1993) -- Morphometrie und Genitalanatomie zweier süddeutscher Populationen von Cochlicopa nitens (Gallenstein, 1848) (Gastropoda: Pulmonata: Cochlicopidae) -- Malakologische Abhandlungen 16: 141-145
To give a deeper insight in the problem of land snail systematics, we analysed the speciation within Cochlicopa. Delimitation of the evolutionary units within this genus has been a controversial issue since decades. Cochlicopa snails are notoriously variable in shell form and in male genitalia structures. The unclear systematics makes the development of conservation strategies difficult. We investigated the phenotypic, molecular and ecological profiles of populations to delimitate the evolutionary units. We conclude that Cochlicopa snails belong to highly self-fertilizing animals. The current species concept for Central Europe categories is as follows:
•Cochlicopa nitens (Gallenstein, 1848): 'good' taxon. Large and bulgy shells; occurs in undisturbed wet lands and calcareous bogs; patchily distributed in central Europe; rare and endangered snail throughout its distribution range. Cochlicopa nitens can be recognized by a combination of habitat characteristics, ITS1-rDNA sequence signals, allozyme patterns and discriminant thresholds of four shell variables.
•The eco-strains of Cochlicopa lubrica (O.F. Müller, 1774): two molecular subgroups predominantly breeding under self-fertilization. The two subgroups evolve through selection-by-habitat (one group prefers moist/shady habitats, the other group is common in dry/exposed habitats); variable in shell size and shell shape; widely distributed throughout Central Europe.
•Cochlicopa lubricella type 1 and C. lubricella type 2 (? Rossmässler, 1834 ?): two independent (paraphyletic) genetic groups, both having small and slender shells. The two groups have not yet been found together within a sampling site. More or less frequent in dry and exposed habitats (limestone rocks, light-radiated forests with calcareous ground, grass land, heath land). The lubricella problem needs to be deeper investigated. One of the two groups seems tightly related to lubrica, hence being a dwarfish and slender form of the latter. Conservation status of both lubricella types is unclear; potentially endangered snails.
I think that the following two species are artificial, and do not exist at all:
Cochlicopa repentina Hudec, 1960: in my opinion C. repentina is not a real taxon; repentinas are just anatomical phenotypes of C. lubrica, e.g. anatomical patterns depend on temperature and/or light-dark environmental conditions
Cochlicopa lohmanderi Waldén, 2001: status unclear; described from southern Sweden, looks at the first glance like a small lubrica type
Note: this taxon-concept of Cochlicopa differs strongly from the “conservative” opinion published by Falkner et al. (2001): Heldia 4: page 31
Further reading
Armbruster GFJ, Böhme M, Bernhard D & Schlegel M (2005) -- The H3/H4 histone gene cluster of land snails (Gastropoda: Stylommatophora): TS/TV ratio, GC3 drive and signals in stylommatophoran phylogeny -- Journal of Molluscan Studies 71: 339-348Korte A & Armbruster GFJ (2003) -- Apomorphic and plesiomorphic ITS-1 rDNA patterns in morphologically similar snails (Stylommatophora: Vallonia), with estimates on divergence time -- Journal of Zoology 260: 275-283
Armbruster G & Bernhard D (2000) -- Taxonomic significance of ribosomal ITS-1 sequence markers in self-fertilizing land snails of Cochlicopa (Stylommatophora, Cochlicopidae) -- Mitteilungen des Museum für Naturkunde Berlin, Zoologische Reihe 76: 11-18
Armbruster G (1997) -- Evaluations of RAPD markers and allozyme patterns: evidence for morphological convergence in the morphotype of Cochlicopa lubricella (Gastropoda: Pulmonata: Cochlicopidae) -- Journal of Molluscan Studies 63: 383-392
Armbruster G (1995) -- Univariate and multivariate analyses of shell variables within the genus Cochlicopa (Gastropoda: Pulmonata: Cochlicopidae) -- Journal of Molluscan Studies 61: 225-235
Armbruster G (1994) -- The taxonomically relevant parts of the male genitalia of Cochlicopa: seasonal variability within two field populations and observations under laboratory conditions (Gastropoda: Pulmonata: Cochlicopidae) -- Malakologische Abhandlungen 17: 47-56
Armbruster G, Schlegel M (1994) -- The land snail species of Cochlicopa (Gastropoda: Pulmonata: Cochlicopidae): presentation of taxon-specific allozyme patterns, and evidence for a high level of self-fertilization -- Journal of Zoological Research and Evolutionary Research 32: 282-296
Armbruster G (1993) -- Morphometrie und Genitalanatomie zweier süddeutscher Populationen von Cochlicopa nitens (Gallenstein, 1848) (Gastropoda: Pulmonata: Cochlicopidae) -- Malakologische Abhandlungen 16: 141-145