New information on the occurrence of two alien decapod crustaceans,Macrobrachium nipponenseandProcambarus virginalis, was summarized for Ukraine. The invasive potential of both species was estimated in the context of local environmental and socio-economic issues. Their history as non-native species is marked by the early use of alien decapods as a natural resource by local residents. Both intentional and unintentional introductions occurred forM. nipponense, while the ornamental trade was an important source of non-nativeP. virginalis. New records ofM. nipponenseandP. virginalisfrom open freshwater habitats in the Odesa and Kharkiv provinces suggest continuing expansion of these decapods. We conducted a molecular phylogenetic analysis ofCOIsequences, which confirmed morphological identifications of invasiveM. nipponense. This reinforces the presumed pathway of this species, including its pathway from China to south-western Ukraine.Procambarus fallaxwas found to be paraphyletic in relation toP. virginalis, which was probably caused by analyzing only one mitochondrial gene, which could be impacted by the recent emergence of the latter species.

The Ponto-Caspian amphipod Dikerogammarus bispinosus was originally described from the Black Sea basin. Its recent discovery in the Caspian Sea basin was puzzling because it was unknown whether it was an invasive or an overlooked native species in this area. Here, we examined specimens collected from both the Black and Caspian Sea basins by means of molecular species delimitation based on nuclear (28S) and mitochondrial (COI) DNA sequences, as well as scanning electron microscopy (SEM). Our analyses reveal that D. bispinosus comprises three evolutionary independent lineages that are molecularly and morphologically distinct. One lineage occurs throughout rivers in the Black Sea basin, while the other two inhabit the Caspian Sea and were found in sympatry, further reinforcing that they are distinct species. Our time-calibrated phylogeny indicates that these lineages split during the Late Miocene-Pliocene, a period corresponding with the separation of the Black and Caspian basins via the Caucasus mountain uplift. SEM imaging revealed morphological differences with respect to setal patterns on the gnathopod propodi among all three lineages. Therefore, our results clearly indicate not only that D. bispinosus is native in the Caspian region, but that it has been overlooked for a long time. Additional populations covering the entire range of this species complex need to be further studied in order to gain a more complete picture of its evolutionary history and resolve its taxonomy.

Here, we investigate the shell shape variation of some closely related freshwater species of the bivalve genus Corbicula using descriptive (qualitative), geometric morphometric and traditional conchometric approaches. The combination of these different approaches allows for an effective discrimination between the species C. fluminalis, C. fluminea and C. leana, as well as an unidentified Corbicula sp. The roundness of the shell hinge is an important diagnostic feature, as are shell sculpture (ribs), symmetry of the apertural margin, and both position and extension of the umbo. We also identify possible hybrids between C. fluminalis and C. leana, with these showing features intermediate to those of the parent species. We examine variability of shell features of C. leana in selected areas in Europe and compare these results with material from the native range of Japan and Korea. For C. leana, we identify two geographic morphotypes from the native area; within Europe, there is a high morphological diversity of this species with several new forms arising, most probably as a result of hybridization.

Marine shelled organisms exhibit diverse growth strategies shaped by species-specific traits and environmental conditions that critically influence their ecological roles, particularly within Marine Animal Forests (MAF), which are structurally complex habitats and biodiversity-rich habitats. This review compiles and compares empirical growth data for 16 bivalve and gastropod species across seven families, classified as full MAF contributors (Pinna nobilis, Flexopecten glaber, Pecten maximus, and Placopecten magellanicus), partial MAF contributors (Cerastoderma edule, C. glaucum, Chamelea gallina, Ruditapes philippinarum, Mercenaria mercenaria, Panopea generosa, Anadara kagoshimensis, A. inaequivalvis, and Tegillarca granosa), and ecologically relevant non-MAF species (Buccinum undatum, Hexaplex trunculus, and Rapana venosa). Age estimation methods included direct techniques, such as shell growth ring and opercular annulus analysis, alongside indirect approaches, such as length-frequency analysis, stable isotope profiling, and mark–recapture studies. Growth trajectories were modelled using von Bertalanffy growth function (VBGF) parameters to estimate the shell size from ages 1 to 4. Based on these estimates, species were categorised into slow, moderate, fast, and exceptional growth groups. These classifications were further explored through hierarchical clustering that grouped species according to their VBGF-derived growth values, revealing consistent and contrasting life history strategies. This comparative analysis should enhance the understanding of molluscan growth dynamics and support the conservation and management of MAF-associated ecosystems by informing restoration planning, guiding species selection, and contributing to evidence-based policy development.