Cochlicopa

Abstract: The following four shell variables were measured on Cochlicopa nitens (n = 150), C. lubricella (n = 205) and ‘C. lubricella’ (n = 545): shell height (‘SH’), shell diameter (‘SD’), diameter of the last whorl (‘DIW’), and diameter of the second last whorl (‘DslW’). As reported in the literature, C. lubrica and C. repentina were assumed to be concho-logically indistinguishable. Therefore, the data pool of ‘C. lubrica’ includes two nominal species. Univariate evaluations allow good separation of ‘C lubrica’ vs. C. nitens (with the variables ‘DslW’ and ‘DIW’), and of ‘C. lubrica’ vs. C. lubricella (with the variables‘SD’ and ‘DIW’). Variable ‘SH’ shows the highest overlap between the threetaxa. For each shell variable thresholds are given for a classification. A very effective tool to separate the groupsis canonical discriminant analysis of the shell variables. Large-shelled forms of C. lubricella should be given more attention. In some cases preliminary notes about important isozymic characters are also given.

Abstract: Genetic differentiation in the four nominal species C. nitens (Gallenstein, 1848), C. lubricella (Porro, 1838), C. lubrica (O. F. Muller, 1774) and C. repentina Hudec, 1960 was studied by investigating 21 isoenzyme loci. Allozymic markers exist, which clearly separate the first three taxa from each other, including in sympatric areas. By contrast, C. repentina and C. lubrica exhibit almost no isozymic differentiation and therefore, C. repentina should not be considered as a separate species, but as a member of C. lubrica sensu lato. The high frequency of homozygotes within all populations of all species shows that self-fertilization is the main breeding system of Cochlicopa. Genetic relationships between the various populations were inferred with different tree-constructing methods. In all phenograms, populations of C. nitens appear in one distinct cluster, whereas the grouping of C. lubricella changes when different clustering-procedures are used. Therefore, it remains unclear whether the three populations of C. lubricella have a common origin or whether they are polyphyletic with at least two independent ancestors.

Abstract: This study deals with the systematic status of the widespread nominal land snail Cochlicopa lubricella (Porro, 1838). Three putative, conchologically distinctive morphotypes of Cochlicopa (Pulmonata: Cochlicopidae) occur in central Europe: C. nitens, C. lubrica, and C. lubricella. Self-fertilization is the main breeding stretegy within each of these nominal species. These three morphotypes were studied with RAPD profiling and the results compared with those of previous investigations using isoenzyme electrophoresis (Armbruster & Schlegel, 1994: J. Zool. Syst. Evol. Res., 32: 282-296). Both sets of molecular data provide evidence against the monophyly of the conchologically classified members of C. lubricella. The strain previously classified as C. lubricella type 1 on shell morphological grounds is genetically indistinguishable from C. lubrica. The strain termed C. lubricella type 2 constitutes a distinctive group. C. lubrica, C. lubricella type 1 and C. lubricella type 2 are more closely related to each other than either is to C. nitens. The molecular data demonstrate the shortcomings of shell morphometric characteristics for determining the taxonomic rank of nominal snail species.

Abstract: A number of studies have reported that consumers affect a range of community-level processes, and in turn their diversity and abundance is influenced by the structure and diversity of the plant community. Although gastropods are important generalist herbivores in many environments, few studies have examined the effects of plant species richness and plant community structure on gastropods. This study investigated gastropod species richness and interactions with various above-ground parameters of the vegetation on an experimental field with four plant treatments: low and high diversity of sown later succession plant species, natural colonization at the start of the experiment and natural colonization after 3 years of continued agricultural practice. The investigated gastropod assemblage contained only seven species and was highly dominated by two of them. Both in pitfalls and with hand-sorting the number of species collected per plot was highest in plots with natural plant colonization. Multivariate analysis revealed that overall gastropod abundance was positively associated with plant height and percentage cover of plants, and negatively with percentage grass cover. The same pattern holds for one of the dominant species-complex (Cochlicopa lubrica/lubricella). The other dominant gastropod species (Deroceras reticulatum) was more abundant in samples with higher percentages of moss cover and higher plant diversity, while less abundant at samples with higher plant cover, indicating that the gastropod species preferences may matter more than just their response to plant diversity. Two plant–gastropod species-level associations were observed: Senecio jacobaea with D. reticulatum and Tanacetum vulgare with Cochlicopa spp. The present study also demonstrated that pitfall-traps are suitable for collecting terrestrial gastropods, at least for species-poor grassland habitats. [KEYWORDS: Cochlicopa spp. ; Deroceras reticulatum ; Plant diversity ; Plant–gastropod interactions ; Terrestrial gastropod diversity ; Vegetation structure]