Since the opening of the Suez Canal in 1869, hundreds of Indo-Pacific species have rapidly colonised the Mediterranean. Understanding the spatial and temporal patterns of this biological invasion is crucial for assessing its ecological impact. A notable example is the non-indigenous oyster Dendostrea sp., first discovered in Türkiye in 1998 and later found throughout the easternmost Mediterranean, though its identity remained uncertain. This study clarifies the taxonomic identity and the introduction pathways of Dendostrea sp. using molecular analyses. Over 100 specimens from 25 sites in the eastern Mediterranean, as well as Île d’Ambre and Rodrigues in the Mauritius Archipelago (the native range), were sequenced for mitochondrial DNA (COI) and compared to 422 sequences from GenBank. Phylogenetic and species delimitation analyses identified the Mediterranean oysters as D. cf. crenulifera, conspecific with oysters from Rodrigues. The Mediterranean populations exhibited high genetic diversity, lack of phylogeographic structure and showed no evidence of a founder effect. These findings suggest that D. cf. crenulifera entered the Mediterranean over two decades ago through multiple shipping-mediated introductions from its native range and successfully established, likely aided by the decline of native biodiversity. The observed genetic diversity pattern across the Mediterranean indicates high propagule pressure driving the species’ invasion history, which likely underpins its establishment success by reducing the deleterious consequences of population bottlenecks and overcoming the so-called genetic paradox. This study underscores the value of molecular surveys in identifying taxonomically challenging non-indigenous species and uncovering their invasion histories.

Cave crickets of the genus Dolichopoda (Orthoptera; Rhaphidophoridae) represent a key component of cave ecosystems. In Italy, nine species are currently known, distributed from the northwestern regions to the southernmost Apennines, with occurrences also along various Tyrrhenian coastal areas and islands, including Sardinia. In this study, we focus on the Apennine region, where we sampled 18 populations of Dolichopoda spp. and sequenced mitochondrial markers (cox1 and 16S) from newly collected individuals to investigate their distribution and genetic diversity. Our analyses identified two previously unrecognized lineages within D. geniculata. Moreover, the sampled caves in the northern Apennines allowed us to refine the distributional ranges of D. geniculata, D. letitiae, and D. schiavazzii. Finally, we provide comments to support a future taxonomic revision of the group.

Snakes introduced outside their native range are an emerging conservation concern because unnoticed populations may establish and impact native vertebrate communities. Here, we investigate two recent extra-range records of the western whip snake ( Hierophis viridiflavus ) in south-western Germany using mitochondrial DNA, phylogeographic network analyses, and local contextual information. Five samples from a waste dump population in Zweibrücken shared the same ND4 haplotype, belonging to a widespread Italian lineage, whereas a road-killed individual from Saarbrücken carried a previously undescribed haplotype of the western lineage. These results indicate two distinct origins. The Zweibrücken population is consistent with human-mediated introduction via long-distance waste transport from Italy, whereas the Saarbrücken record may reflect arrival from the nearby French range margin. Preliminary surveys suggest possible local impacts on native lizards. This case highlights waste movement as a potentially overlooked pathway for snake introductions, with ecological and sanitary implications.

Since the opening of the Suez Canal in 1869, hundreds of Indo-Pacific species have rapidly colonized the Mediterranean. Understanding the spatial and temporal patterns of this invasion is crucial for assessing its ecological impact. A notable example is the Lessepsian oyster Dendostrea sp., first discovered in Turkey in 1998 and later found throughout the easternmost Mediterranean, though its identity remained uncertain. This study clarifies the taxonomic identity and the introduction pathways of Dendostrea sp. using molecular analyses. Over 100 specimens from 25 sites in the Eastern Mediterranean, as well as Mauritius and Rodrigues (the native range), were sequenced for mitochondrial DNA (COI) and compared to 422 sequences from GenBank. Phylogenetic and species delimitation analyses identified the Mediterranean oysters as D. aff. crenulifera, conspecific with oysters from Rodrigues. The Mediterranean populations exhibited high genetic diversity, lack of phylogeographic structure, and showed no evidence of a founder effect. These findings suggest that D. aff. crenulifera entered the Mediterranean over two decades ago through multiple shipping-mediated introductions from its native range and successfully established, likely aided by the decline of native biodiversity. The observed genetic diversity pattern across the Mediterranean indicates high propagule pressure driving the species' invasion history, which likely underpins its establishment success by reducing the deleterious consequences of population bottlenecks and overcoming the so-called genetic paradox. This study underscores the value of molecular surveys in identifying taxonomically challenging non-indigenous species and uncovering their invasion histories.

The Mediterranean Sea is a major hotspot of non-indigenous species, many of which arrive through the Suez Canal and spread via vessel-mediated transport. Among them, the tropical oyster Dendostrea cf. crenulifera has long been affected by taxonomic uncertainty. By integrating morphological characters with mitochondrial cox1 sequences from 38 specimens collected in nine localities of Greece, Croatia and Italy, we provide the first molecularly validated evidence of its occurrence outside the Levantine basin. New records from the Aegean Sea, Libyan Sea, Ionian Sea, Adriatic Sea and southern Tyrrhenian Sea extend the known range by more than 1000 km westwards. Specimens from Crete were found on natural rocky substrates, whereas those from all western localities occurred exclusively on artificial structures in harbours and marinas, supporting hull fouling as the primary vector of spread. The ability of this tropical oyster to establish in environmentally diverse basins, including areas where native oysters occur, suggests the potential for spatial overlap and competitive interactions. The early detection of this range expansion offers opportunities for monitoring and for the assessment of its ecological implications.

Kotschy’s gecko, Mediodactylus kotschyi, is native to the Eastern part of the Mediterranean Basin and a successful colonizer, with an extensive distribution across the Balkans and outside its native range. In Serbia, it was presumed native in Prizren (Kosovo and Metohija province) and introduced across the remaining territory. To explore the origin of Serbian Kotschy’s gecko, we collected specimens from most of the Serbian populations where the species was recorded and assessed their phylogenetic relationships based on three mtDNA markers (COI, cytb, 16S rRNA) under Maximum Likelihood (ML) and Bayesian Inference (BI) approaches. First, our results support that the specimens found in Serbia belong to M. kotschyi. Second, all populations except Prizren belong to the subspecies M. kotschyi skopjensis. Furthermore, the Italian populations are sister to the specimens from Prizren, suggesting a Balkan origin for these populations, which settled in Apulia likely through ancient human-mediated dispersion. The small genetic differentiation found suggests that Kotschy’s gecko rapidly colonized the Central Balkans, originating from Northern Greece and North Macedonia. The results also suggest a story of multiple, complex (most likely) human-mediated introductions. However, further studies should be conducted to properly elucidate the colonization pathways, and to truly disentangle the potential fast natural range expansion from an anthropogenic dispersion of this gecko species.