Frank Walther

Systematic revision and molecular phylogeny of the land snail genus Fruticocampylaea (Gastropoda: Hygromiidae) from the Caucasus region

This paper presents a systematic revision and a molecular phylogenetic analysis of the Caucasian land snail genus Fruticocampylaea. The genus is newly delimited based on the reduction of the cavities adjoining the seminal duct in the penial papilla. Shell and genitalia of all five species (F. narzanensis, F. kobensis, F. tushetica sp. nov., F. christophori, F. daghestana) are described and figures provided. All synonyms and all locality records are listed. Maximum likelihood and Bayesian analyses of mitochondrial and nuclear DNA sequences (fragments of cox1, 16S rDNA, ITS2 and 28S rDNA) confirm the monophyly of Fruticocampylaea. The reduction of the dart apparatus and the conical plug, via which the dart apparatus inserts into the vagina, as well as the molecular phylogenetic analyses, suggests a sister group relationship between Fruticocampylaea and Circassina (without Abchasohela). Furthermore, the molecular phylogenetic analyses indicate that the Fruticocampylaea species originated in a rapid radiation. The uplift of the Greater Caucasus in the Late Miocene or Pliocene or climatic changes at the end of the Pliocene or in the early Pleistocene may have caused the radiation of Fruticocampylaea. Low intraspecific variability can be explained by population bottlenecks during Pleistocene glacial periods followed by postglacial population increase. http://zoobank.org/urn:lsid:zoobank.org:pub:AB15158D-21A3-4945-8D49-F7DE8E406E2B

Morphological and genetic differentiation of Eremina desertorum (Gastropoda, Pulmonata, Helicidae) in Egypt

To understand the processes that result in morphological and genetic diversity, we studied the differentiation of the land snails Eremina d. desertorum and Eremina desertorum irregularis in the deserts of northern Egypt. These two taxa are differentiated with regard to shell size and shape and are separated by a narrow hybrid zone west of Alexandria. The lack of differences in the genitalia and the lack of reciprocal monophyly of the mitochondrial haplotypes of E. d. desertorum and E. desertorum irregularis support their classification as subspecies rather than distinct species. Low genetic distances indicate that the differentiation is probably less than half a million years old. The genetic data indicate a population expansion in agreement with other evidence that the Nile region in northern Egypt was more humid well into historical times than today. Shell size and shape are correlated with a climatic gradient from cooler and more humid conditions along the Mediterranean coast to arid and hot conditions in the interior. The decrease of body size with decreasing precipitation and increasing temperature might be explained by limited time for food intake in the more arid regions. The shape differences between the taxa are partly an indirect consequence of selection for body size, but are also directly affected by selection for reduction of aperture size.

Species complex or complex species? Integrative taxonomy of the land snail genus Rossmaessleria (Gastropoda, Helicidae) from Morocco and Gibraltar

We applied an integrative approach to re-evaluate the taxonomy of the conchologically highly diverse land snail genus Rossmaessleria from the Rif Mountains in Morocco and from Gibraltar, which has been classified into 12 nominal species so far. An analysis of cox1 and 16S rDNA sequences using the General Mixed Yule-coalescent approach with a single or multiple thresholds, its Bayesian implementation as well as the Automatic Barcode Gap Discovery method indicated that all Rossmaessleria populations can be classified into a single species, R. scherzeri (Zelebor, 1867). This result is confirmed by the lack of diagnostic differences in the genitalia as shown in a principal component analysis of the genital measurements. The variation of shell characters also does not allow an unambiguous subdivision of the complex. However, the populations of a mountain or a mountain ridge share characteristic combinations of shell characters so that they can be classified as geographic subspecies. The delimitation of the subspecies and their distribution is discussed and three subspecies are described as new to science: R. scherzeri periclitata ssp. nov. R. scherzeri ingae ssp. nov., and R. scherzeri eleanorae ssp. nov. http://zoobank.org/urn:lsid:zoobank.org:pub:187FE235-A257-423F-8FC3-957117546400

Presumable incipient hybrid speciation of door snails in previously glaciated areas in the Caucasus

Homoploid hybrid speciation, speciation by hybridization without a change in chromosome number, may be the result of an encounter of closely related species in a habitat that is different from that usually occupied by these species. In the northwestern Caucasus the land snail species Micropontica caucasica and M. circassica form two distinct entities with little admixture at low and intermediate altitudes. However, at higher altitudes in the Lagonaki plateau, which were repeatedly glaciated, Micropontica populations with intermediate characters occur. Admixture analyses based on AFLP data demonstrated that the populations from the Lagonaki plateau are homoploid hybrids that now form a cluster separate from the parental species. The Lagonaki populations are characterized by a mtDNA haplotype clade that has been found in the parental species only once. The fixation of this haplotype clade in most hybrid populations suggests that these haplotypes are better adapted to the cooler conditions in high altitude habitats and have replaced the haplotypes of the parental species in a selective sweep. The fixation of a presumably adaptive mitochondrial haplotype clade in the Lagonaki populations is an important step towards speciation under the differential fitness species concept.

Phylogeny and reclassification of the Caucasigenini radiation from the Caucasus region (Gastropoda, Hygromiidae)

The Caucasigenini is an endemic radiation of hygromiid land snails from the Caucasus region. A phylogenetic analysis of morphological characters of the genitalia and the shell showed that the morphological characters are insufficient for resolving the relationships within the Caucasigenini. Convergences of the few parsimony informative characters in other groups of the Hygromiidae demonstrate that these characters are not reliable indicators of phylogenetic relationships. Phylogenetic analyses of sequences of cox1, 16S rDNA, 5.8S rDNA, ITS2 and 28S rDNA revealed several well‐supported groups. The relationships among these groups could not be resolved. It is likely that these groups originated in a rapid radiation during the uplift of the Caucasus. Based on the molecular phylogeny, we propose a new classification of the species of the Caucasigenini and establish a new genus, Lazicana gen. n.

High gene flow despite opposite chirality in hybrid zones between enantiomorphic door snails

We studied differentiation and geneflow patterns between enantiomorphic door‐snail species in two hybrid zones in the Bucegi Mountains (Romania) to investigate the effects of intrinsic barriers (complications in copulation) and extrinsic selection by environmental factors. A mitochondrial gene tree confirmed the historical separation of the examined populations into the dextral Alopia livida and the sinistral Alopia straminicollis in accordance with the morphological classification, but also indicated gene flow between the species. By contrast, a network based on amplified fragment length polymorphisms (AFLP) markers revealed local groups of populations as units independent of their species affiliation. Admixture analyses based on AFLP data showed that the genomes of most individuals in the hybrid zones are composed of parts of the genomes of both parental taxa. The introgression patterns of a notable fraction of the examined markers deviated from neutral introgression. However, the patterns of most non‐neutral markers were not concordant between the two hybrid zones. There was also no concordance between non‐neutral markers in the two genomic clines and markers that were correlated with environmental variables or markers that were correlated with the proportion of dextral individuals in the populations. Neither extrinsic selection by environmental factors nor intrinsic barriers resulting from positive frequency‐dependent selection of the prevailing coiling direction were sufficient to maintain the distinctness of A. straminicollis and A. livida. Despite being historically separated units, we conclude that these taxa now merge where they come into contact.

Leiostyla beatae n. sp. from eastern Georgia (Gastropoda: Lauriidae)

Leiostyla R.T. Lowe, 1852 is a disjunctly distributed pupilloid group of land snails known from the Macaronesian islands, Western Europe, Algeria, Bulgaria, Turkey, the Caucasus region and Iran (Pilsbry 1922-1923; Schileyko 1984; Gittenberger & Pieper 1988; Hausdorf 1990). In the Neogene the genus was more widespread in Central and Western Europe (Pilsbry 1922). Thus, the Caucasus region and the Macaronesian islands, where the highest recent diversity of Leiostyla species is found (Pilsbry 1922-1923), can be considered refugial areas.

Clarification of the systematic position of Patula spatiosa Lindholm, 1922 from eastern Turkey (Mollusca: Gastropoda)

One of the most mysterious taxa of the terrestrial snail fauna of Turkey is Patula spatiosa Lindholm, 1922. This large species has been described from a single specimen collected in 1914 allegedly in the Kars region (nowadays easternmost Turkey). Up to date, no further specimens have been reported. Its taxonomical position is unclear, even on the family level.

The Identity of Inobseratella Lindholm, 1924 and Its Type Species Clausilia lantzi Lindholm, 1924 (Gastropoda: Clausiliidae) from Northeastern Turkey

Inobseratella Lindholm, 1924, and the only included species Clausilia (Inobseratella) lantzi Lindholm, 1924, were described by Lindholm (1924) based on a single specimen as the “first Caucasian species, in which there is no clausilium”. However, Likharev (1962) recognized that there is a broken stalk of a clausilium in the holotype. He placed C. lantzi in the synonymy of Armenica brunnea (Rossmässler, 1839). Nordsieck (1979) obviously doubted this identification and classified Inobseratella as incertae sedis. Although the holotype of C. (Inobseratella) lantzi is available in the Zoological Institute of the Russian Academy of Sciences in St.-Petersburg, the identity of the taxon has not been clarified thus far. Clausilia lantzi was one of the first clausiliid species described from the eastern Pontus Mountains. Several endemic species and genera were described later from this region, which might turn out to be junior synonyms of C. lantzi or Inobseratella. We studied the holotype of C. (Inobseratella) lantzi, figured it for the first time and clarified the identity of C. lantzi and Inobseratella to stabilize the nomenclature.

Phylogeographic analyses reveal Transpontic long distance dispersal in land snails belonging to the Caucasotachea atrolabiata complex (Gastropoda: Helicidae)

The phylogeography and population structure of land snails belonging to the Caucasotachea atrolabiata complex in the Caucasus region was investigated to obtain a better understanding of diversification processes in this biodiversity hotspot. So far the complex has been classified into three species, C. atrolabiata from the north-western Caucasus, C. calligera from Transcaucasia and C. intercedens from the eastern Pontus Mountains. Phylogenetic (neighbor-net and neighbor-joining tree) as well as admixture analyses based on AFLP data showed that the complex consists of two population clusters corresponding to C. atrolabiata and C. calligera. The populations assigned to C. intercedens in fact represent hybrids consisting of different proportions of the genomes of C. atrolabiata and C. calligera. There is a broad transition zone between C. atrolabiata and C. calligera in the Pontic Mountains and a second transition zone in Abkhazia. Because of evidence for gene flow, it is suggested to classify the two aforementioned taxa as subspecies, namely C. a. atrolabiata and C. a. calligera. The presence of mitochondrial C. a. atrolabiata haplotypes in Turkey can only be explained by passive dispersal across the Black Sea. The distribution of C. a. atrolabiata and additional cases of land snails with disjunct Transpontic distribution patterns cannot be ascribed to a common cause but are results of long distance dispersal events at different times.