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.
Leeches of the genus Limnatis Moquin–Tandon, 1827 infest mucous membranes of various mammals, including humans and domestic ungulates. The type species of the genus L. nilotica (Savigny, 1822) was initially thought to occur throughout the Western Palaearctic, from North Africa to the Middle East and Central Asia. It was later found that L. paluda (Tennent, 1859) is a widespread Western Asian species. However, the South Caucasus and vast areas of Central Asia have not been explored sufficiently in terms of leeches of the genus Limnatis. We recorded L. paluda from Azerbaijan and Uzbekistan for the first time. We also carried out the first molecular characterisation of L. nilotica herein. We found a deep genetic differentiation (8 %) between the Western Asian L. paluda and North African (Moroccan) L. nilotica based on their COI sequences. This finding corroborates a previous morphology–based hypothesis on their separate species assignments. The low genetic diversity of L. paluda is explained by the recent colonisation of arid landscapes of Western Asia.
The gastropod Rapana venosa (Valenciennes, 1846) is a successful worldwide invader occurring in the Black Sea. The aim of this study is to overview specific population features of this mollusk from Odesa Bay through integrative systematic approach by means of morphological and molecular research. For this purpose, the mollusks were collected from the Black Sea and examined using morphological methods: traditional morphometry, which employs linear parameters of shells (height, width, whorl height, whorl width, height of the last whorl) and shell weight, and geometric morphometrics of the shell shape data. For a molecular genetic test, the COI gene region was used. Among all conchological variability, the two morphotypes were defined: the first has a “broad” shape — shells have a thick and durable last whorl and a low spire, and the second one — “extended” shape: shells are relatively slender with an elongated high-conical spire. According to the geometric morphometric data, R. venosa has statistically significant differences between defined morphotypes (F = 4.12, p = 0.001); however, the shapes in males and females are not significantly different (F = 1.13, p = 0.318). No genetic diversity, neither novel haplotypes were revealed by the molecular analysis: in Odesa Bay, the haplotype occurring also in other regions of invasion across the world is present.
New information on the occurrence of two alien decapod crustaceans, Macrobrachium nipponense and Procambarus 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 for M. nipponense, while the ornamental trade was an important source of non-native P. virginalis. New records of M. nipponense and P. virginalis from open freshwater habitats in the Odesa and Kharkiv provinces suggest continuing expansion of these decapods. We conducted a molecular phylogenetic analysis of COI sequences, which confirmed morphological identifications of invasive M. nipponense. This reinforces the presumed pathway of this species, including its pathway from China to south-western Ukraine. Procambarus fallax was found to be paraphyletic in relation to P. virginalis, which was probably caused by analyzing only one mitochondrial gene, which could be impacted by the recent emergence of the latter species.
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