Speciation in sympatric species of land snails from the genus Trochulus (Gastropoda, Hygromiidae)

Next step in Monachacantiana (Montagu, 1803) phylogeography: northern French and Dutch populations (Eupulmonata, Stylommatophora, Hygromiidae)

Features of shell and genitalia as well as nucleotide sequences of selected mitochondrial and nuclear genes of specimens of Monachacantiana from ten northern French and two Dutch populations were compared with the same features of British and Italian populations. They were found to be very similar to populations previously identified as belonging to the CAN-1 lineage of M.cantiana. This confirms previous suggestions that M.cantiana was introduced to western Europe (England, France and the Netherlands) in historical times.

High-throughput degraded DNA sequencing of subfossil shells of a critically endangered stenoendemic land snail in the Aegean

High-throughput sequencing has enabled the comprehensive genetic exploration of biological diversity, especially by using natural history collections to study hard-to-find, threatened or even extinct-in-the-wild taxa. Mollusk shells are under-exploited as a source for DNA-based approaches, despite their apparent advantages in the field of conservation genetics. More particularly, degraded DNA techniques combined with high-throughput sequencing have never been used to gain insights about the DNA preservation in land snail subfossil or historical shells. Here, we applied degraded DNA analysis on two historical shells of Levantina rechingeri, a stenoendemic Critically Endangered species that has never been found alive, in order to explore the patterns of DNA preservation on land snail shells originating from the eastern Mediterranean, as well as to infer its molecular phylogenetic placement. Our results showed that centuries to decades-old DNA from an empty shell collected in an Aegean island exhibits characteristic post-mortem damage patterns similar to those observed in ancient DNA from eastern Mediterranean terrestrial animals, setting a precedent for future museomics studies on taxa distributed in areas with similar climate. Finally, genome skimming of the empty shell allowed high coverage of multiple nuclear and mitochondrial loci, enabling the phylogenetic placement of the focal taxon, the re-evaluation of its taxonomic classification, and the revealing of a new Aegean land snail lineage, Aristina genus novum. This approach is a non-invasive way to sample DNA from threatened land snail species and suitable to study the evolutionary history of taxa with cryptic ecology, stenoendemics, or extinct-in-the-wild, as well as old museum specimens.

On the verge of extinction - revision of a highly endangered Swiss alpine snail with description of a new genus, Raeticella gen. nov. (Gastropoda, Eupulmonata, Hygromiidae)

The phylogenetic status of the alpine land snail Fruticicolabiconica has remained questionable since it was described by Eder in 1917. Considered a microendemic species from mountain tops in Central Switzerland, the shell is specially adapted for life under stones. Herein, we show via molecular and anatomical investigations that F.biconica neither belongs to the land snail genus Trochulus, nor to any other genus within Trochulini, but rather warrants placement within the newly established genus Raeticella Kneubühler, Baggenstos & Neubert, 2022. Phylogenetic analyses reveal that R.biconica is clearly separated from Trochulus. These findings are supported by morphological investigations of the shell and genitalia.

Molecular phylogeny of the genus Chondrina (Gastropoda, Panpulmonata, Chondrinidae) in the Iberian Peninsula

Chondrina Reichenbach, 1828 is a highly diverse genus of terrestrial molluscs currently including 44 species with about 28 subspecific taxa. It is distributed through North Africa, central and southern Europe, from Portugal in the West to the Caucasus and Asia Minor in the East. Approximately 70% of the species are endemic to the Iberian Peninsula constituting its main center of speciation with 34 species. This genus includes many microendemic taxa, some of them not yet described, confined to limestone habitats (being strictly rock-dwelling species). They are distributed on rocky outcrops up to 2000 m.a.s.l. It is a genus of conical-fusiform snails that differ mainly in shell characters and in the number and position of teeth in their aperture. So far, molecular studies on Chondrina have been based exclusively on the mitochondrial Cytochrome Oxidase subunit I region (COI). These studies gave a first view of the phylogeny of the genus but many inner nodes were not statistically supported. The main objective of the study is to obtain a better understanding of the phylogeny and systematics of the genus Chondrina on the Iberian Peninsula, using multilocus molecular analysis. Partial sequences of the COI and 16S rRNA genes, as well as of the nuclear Internal Transcribed Spacer 1 (ITS1-5.8S) and Internal Transcribed Spacer 2 (5.8S-ITS2-28S) were obtained from individuals of all the extant Chondrina species known from the Iberian Peninsula. In addition to this, the newly obtained COI sequences were combined with those previously published in the GenBank. Phylogenetic relationships were inferred using maximum likelihood and Bayesian methods. The reconstructed phylogenies showed high values of support for more recent branches and basal nodes. Moreover, molecular species delimitation allowed to better definethe studied species and check the presence of new taxa.

Phyllidiidae (Nudibranchia, Heterobranchia, Gastropoda): an integrative taxonomic approach including chemical analyses

Members of the widely distributed and common nudibranch family Phyllidiidae are often easily spotted in the marine environment because of their conspicuous colours and obvious presence on the reef. They are interesting with regard to their defensive chemical compounds that may lead to new drug discoveries. Despite their abundance, the family is also well known for its taxonomic problems and the difficulties in species identification due to very similarly coloured species and lack of morphological characters. In this study, phyllidiid species were analysed using an integrative approach. Molecular analysis of the mitochondrial genes 16S and CO1 was utilised, running phylogenetic analyses, species delimitation tests, and haplotype network analyses. Additionally, for the first time, external morphological characters were analysed, museum material was re-analysed, and chemical profiles were applied for characterising species. The analyses are based on sequences of 598 specimens collected in Indonesia by the team, with the addition of published sequences available on GenBank. This study comprises 11 species of Phyllidia, seven species of Phyllidiopsis, and at least 14 species of Phyllidiella. Moreover, 11 species belonging to these three genera are probably new to science, Phyllidiopsis pipeki is synonymised with P. krempfi, and Phyllidiella albonigra is resurrected. Some of the external colouration previously used for species identification is shown to not be valid, but alternative characters are provided for most species. Chemical analyses led to species characterisation in a few examples, indicating that these species use particular sponge species as food; however, many species show a broad array of compounds and are therefore characterised more by their composition or profile than by distinct or unique compounds.