The article presents the first overview of animal invasions in Armenia with a national comprehensive combined list of documented invasive alien animal species. This list includes 40 species from various taxa of invertebrates and vertebrates, including nematodes, annelids, crustaceans, insects, mollusks, fish and mammals. For each species, we present data on the range of invasion in the territory of Armenia, indicating the corresponding naturalization time and introduction pathway. The number of invasions has been growing exponentially since 1940. Fifteen out of the overall 40 species have been registered in the last five years. Most of the invertebrate species were likely introduced unintentionally, while vertebrate species were mainly intentionally introduced through release into the nature or escape from aquaculture or farming. Importantly, the inventory of invasive alien animal species in Armenia, which could potentially cause negative effects on the economy, nature, or human health, will aid in risk assessment and development of a country- and region-wide management policy for biological invasions.

A species belonging to the genus Sagina, that has been known since at least 2016 from several localities in the city of Bassano del Grappa (Veneto region, northeastern Italy), was identified as S. maxima. It is a species from (predominantly) coastal areas in western North America and Far Eastern Asia. Morphological and molecular data confirmed this identification, although this finding raises some questions about the ecology and morphology of S. maxima and some of its relatives and/or similar-looking species. These records appear to be the first in Europe. A concise morphological description and illustrations are provided along with a comparison with related and similar-looking Sagina species. The status of S. maxima in Italy is also briefly discussed and a key for the identification of the Italian species from the genus is presented.

This study updates the distribution and status of Arctotheca calendula (L.) Levyns (Asteraceae, Cichorioideae) in continental North Africa (Algeria and Tunisia). Field surveys carried out mainly in northeastern Algeria (from 2021 to 2024) and northern Tunisia (from 2004 to 2023) by the first two authors, led to the identification of a total of 13 new localities (5 in Algeria and 8 in Tunisia), some of which are located far from the locations where the plant was previously reported by other authors. Our results showed that A. calendula spreads in a westward direction in Algeria from the first recorded occurrence (El Behaira pond). To the contrary, in Tunisia the species spreads towards the north, east and west from the first recorded occurrence (Sejnane). Currently, in both Algeria and Tunisia, the species colonizes exclusively wetlands, but a possible future expansion into other habitats, notably coastal dunes and beaches, cannot be ruled out. Additionally, the species is likely to spread into western Algeria as it was recently detected just 7 km from the border between Algeria and Morocco where it is widespread. To highlight this spread, a map of the current distribution of A. calendula within continental North Africa (mainly Algeria and Tunisia) and field images are provided; the possible negative impacts of the species are also discussed. As a result of this work, A. calendula can be defined as a species with high invasive potential in continental North Africa. Its invasion in Algerian and Tunisian wetlands requires the implementation of a management plan to control its further spread within these threatened ecosystems. Hand-pulling is, in our opinion, the best solution, but it needs to be implemented quickly before the species’ range expands further, notably in Algeria.

Subterranean termites (Family Rhinotermitidae) and drywood termites (Family Kalotermitidae) can be pest species as they have the potential to inflict damage to wooden constructions and can therefore cause a significant economic impact. Some species of these families are highly destructive and are invasive in many parts of the world. New introductions and/or the spread of termites are often caused by import of infested wood, plants or soils. The present study reports the first records of three exotic termite species in Belgium, viz. Cryptotermes brevis and Reticulitermes banyulensis in Brussels (Brussels Capital Region), and Reticulitermes flavipes in Brugelette (Hainaut province; Walloon region). The morphological identification of the specimens (N = 8) was validated by DNA-barcoding. Cryptotermes brevis and Reticulitermes banyulensis infestations are probably of little concern as local climatological conditions make it unlikely for either species to survive in the temperate climate in Belgium. In contrast, it is likely that Reticulitermes flavipes may become established and will spread to other sites in Belgium.

Melanoplus differentialis, which is a pest native to the Americas, causes serious damage to landscape trees and farmland. It has adapted to the domestic environment and is on the rise. M. differentialis was first identified on natural habitat in 2020 in Ulsan. This study aims to identify the habitat status, host plants, and ecological characteristics of M. differentialis in South Korea. Melanoplus differentialis overwinters in egg pods in the ground. Nymphs were identified from April, and adults from June to November. M. differentialis was distributed in a region, which consisted of 16 orders, 18 families, and 32 species of host plants, among which M. differentialis preferred species of Asteraceae and Fabaceae plants. On measuring the soil temperature at oviposition sites during the overwintering season, the minimum soil temperature in winter was 0.37 °C from December 2020 to March 2021 and 2.3 °C from December 2021 to March 2022. The results provide basic data that could facilitate the minimization of damage to ecosystems and crops by determining the habitat status and ecological characteristics of M. differentialis in South Korea.

In the Galapagos Islands, invasive wasps negatively affect the local fauna through competition with native predators. These wasps also pose a risk to humans because of their stings. Thus, it is important to constantly survey these insects. Currently there are three species of vespids known from the Galapagos: two social species are invasive, while a solitary species is cryptogenic. After structured sampling using malaise traps, hand nets, and pan traps on most of the islands of the archipelago, and a review of related collections, the distribution of Brachygastra lecheguana is expanded to Genovesa Island; precise localities and vegetation zones are recorded for Polistes versicolor; and updated information on the distribution of the cryptogenic solitary vespid Pachodynerus gaullei is provided.

The current study presents an up-to-date distribution denotating the expansion of the brown anole lizard (Anolis sagrei), an invasive species, in continental Ecuador. The brown anole represents a significant threat to biodiversity through displacement of native species, facilitated by its adaptability and dominance. Our sampling effort covering from 2018 to 2022 and iNaturalist reports between 2015 and 2023, to take into consideration citizens observations, revealed an expanded distribution across provinces along the Ecuadorian coast and one in the Amazon region. Notably, the brown anole’s presence in urban areas of Guayas province, including Samborondon and Guayaquil, raises concerns about potential impacts on local ecosystems. The lizard’s adaptability is evident in its ability to thrive in various habitats, including urban parks, gardens, and natural areas along riverbanks. Despite extensive surveys, no brown anoles were found in natural forests in the mainland, so until today no potential impacts on native species are expected; except for a reserve in a continental island where two brown anoles were already sighted. The study emphasizes the need for effective management responses, including identification, understanding expansion processes, and anticipating ecological impacts. Our study provides the baseline for the environmental authority to identify the areas were controlling the brown anole’s spread if fundamental, particularly in priority conservation areas.

The brown seaweed Rugulopteryx okamurae (Dictyotales, Ochrophyta), native to the Pacific Ocean and widely distributed in Asia, has been recently recognized as an emblematic case of biological invasion by marine macroalgae in European waters. Since 2015 and from the Strait of Gibraltar, R. okamurae has rapidly spread towards Atlantic and Mediterranean coastal areas exhibiting an invasive behaviour with significant ecological and socio-economic impacts. Here, we report the first morphologically and genetically confirmed observation of this species in Italy, along the north-western coast of Sicily (Gulf of Palermo). Specimens were found as drifted material and as an established population on Posidonia oceanica, representing its new eastern distribution limit in the Mediterranean Sea, as the species was previously established in Marseilles (France). Furthermore, we performed a favorability distribution model with the current introduced distribution of the species for the Mediterranean, which shows most of the western Mediterranean, including the Balearic archipelago, Corsica and Sardinia, central Mediterranean, including Sicily, and the northern coast of Africa together with eastern Mediterranean basin, as highly favorable for R. okamurae. The most probable vectors for this introduction are sea currents and maritime traffic, including fishing activities. This hypothesis was supported by some of the ranked variables in the favorability model, i.e., current velocity, and the proximity of the introduced population to fishing ports. These results are a warning that the species can cover large sea distances via sea currents, thus also threatening the ecosystems and marine resources of the central and eastern Mediterranean Sea, as these areas are forecasted to be highly favorable regions for the species. We suggest coordinated actions at the European level with stakeholders in the fishing sector regarding prevention, both because it is a highly affected sector and because it potentially has a very important role in the dispersion of the species.

Recently, using morphological and molecular analyses, several Pseudopolydora specimens (Polychaeta: Spionidae) from French coastal waters were identified as Pseudopolydora kempi ssp. japonica Imajima and Hartman, 1964. According to the samples examined, P. kempi ssp. japonica has been present in European waters since 2004. Previous misidentifications in France are likely due to its resemblance to the indigenous species Pseudopolydora pulchra (Carazzi, 1893), and to the status of P. kempi ssp. japonica which is still controversial. Material was collected from Arcachon Bay, Morbihan Bay, Aiguillon Bay, and in the Gironde estuary (Bay of Biscay, France). All these areas have extensive shellfish industries, especially the farming of the Japanese oyster Magallana gigas (Thunberg, 1793). The importation of these live oysters from Japan has often included other species including polychaete worms, indicating a major vector of exotic species.

A crucial first step in managing marine non-indigenous species (NIS) that pose a threat to native species, habitats or ecosystems is for countries to update their NIS lists. In the Mediterranean region, efforts to update these lists vary greatly from country to country. There is a notable disparity between the northern and southern coasts of this basin, which warrants attention to ensure a comprehensive assessment of the management and dissemination of NIS along the Mediterranean coasts. In this context, a rapid assessment survey was carried out along the Tunisian coasts in five marinas: Bizerte, Gammarth, Hammamet, Port El Kantaoui and Cap Monastir. NIS belonging to the five sessile macrozoobenthic groups Ascidiacea, Bryozoa, Porifera, Hydrozoa and Polychaeta in different substrata of these marina habitats were surveyed in May and December 2019. Here we report a total of twenty NIS and cryptogenic species with six new records in Tunisian marinas: Phallusia nigra Savigny, 1816; Clavelina oblonga Herdman, 1880; Ciona robusta Hoshino & Tokioka, 1967; Didemnum cf. vexillum Kott, 2002; Botrylloides cf. niger Herdman, 1886 and Bugula stolonifera (Ryland, 1960). Our findings suggest that it is important to monitor buoys when trying to detect NIS and cryptogenic species.

The Pacific oyster (Crassostrea gigas) is an important commercial species introduced to Mexico in the 1970s for aquaculture production. A purportedly infertile triploid variety of this species was authorized for farming in the El Vizcaino Biosphere Reserve (EVBR), to generate economic benefits for local residents while at the same time avoiding offsite propagation. Nevertheless, the presence of oysters at Ojo de Liebre lagoon, a core area of the reserve, has been observed. To test for the occurrence of C. gigas beyond its rearing areas, 240 oysters were collected from 10 sites in the lagoon and analyzed on the basis of its morphology and with the mitochondrial cytochrome oxidase subunit I; these approaches positively identified 95 and 70 C. gigas specimens respectively, corroborating the existence of individuals living outside the farming areas in the core zone of the reserve. Histological examinations discovered oysters with gonads in different stages of maturity (including spawning), verifying that the free-ranging specimens were reproductively active. We propose three hypotheses of how colonization of C. gigas took place at EVBR: the recruitment of larvae from unknown nearby populations, the inadvertent introduction of diploid organisms in the aquaculture facilities, and the possibility that triploid specimens growing in the local hatcheries have produced viable diploid gametes. Although C. gigas should be considered as an introduced species at the reserve, its population size is small, the specimens mostly settled on artificial substrata and do not cover large areas on the bottom, and there is no evidence of ecological damage or substitution of resident species. We suggest that the Pacific oyster is in the first stages of colonization in the EVBR, and that collaborative work of reserve managers and producers have the possibility to address the invasion and minimize potential negative effects on the local ecosystems, as well as possible dispersal to other areas.

Mytilopsis sallei is a small bivalve that has invaded Asian waters, including southeast Asia. This shellfish has become a pest in coastal and estuary waters in Southeast Asia. This study is the first report on the presence and structure of the M. sallei population in Indonesia, precisely in the coastal lakes of Medan City, North Sumatra Province. This research was conducted in Lake Siombak, Medan City, North Sumatra, which is one of the tropical tidal lakes in Indonesia. Mytilopsis sallei shellfish samples were taken for a year from September 2018–August 2019. Mytilopsis sallei were obtained using a Petersen Grab with a mouth opening of 30 × 30 cm. The measurement of M. sallei consisted of the shell length, shell width, shell thickness, and body weight. The analysis of the population structure parameters with ELEFAN I was accommodated in the FiSAT II software. Spatially, M. sallei highest density in Siombak Lake is at station 5 with 24,100 and 23,948 ind.m^-2 and the lowest at station 7 is only 967 ind.m^-2. Monthly, M. sallei hase the highest density in the dry season (Feb–Jul) compared to the wet season (Aug–Jan). The density of M. sallei in the dry season reaches 1213–13,187 ind.m^-2 and in wet seasons reaches 369–3,029 ind.m^-2. The Mytilopsis sallei in Siombak Lake has a maximum length of 42.14 mm and the smallest size is 3.00 mm. The growth model of M. sallei in Lake Siombak is Lt = 42.14 (1−e^{-1.1(t-0.1598)}). Mytilopsis sallei recruitment took place in January (fifth month). The instantaneous mortality rate (Z) of M. sallei mussels was 5.32 with an exploitation rate (E) of 0.66.

The Caspian Sea is the largest lake-type water body and one of the hotspots for aquatic bio-invasions. The present work documents the occurrence of invasive Palaemon macrodactylus in Iranian waters of the southern Caspian Sea. The morphological criteria of the specimens found undoubtedly agree with those of the species Palaemon macrodactylus Rathbun, 1902. During spring-summer 2015, the first specimens of P. macrodactylus were observed in the Gorgan Bay, southeastern Caspian Sea (2.9% of total abundance of palaemonid species). They were named an unknown species at that time. In the second survey in 2019–2020, P. macrodactylus has shown a slight increase in abundance (4.77%) in the bay, indicating the population of this species is evidently expanding in the area and successfully established in the southeastern Caspian Sea. Given its ability to be a successful invader in the new area of introduction, it could have adverse consequences for local biota, especially local shrimps (P. elegans and P. adspersus). Considering the possible invasion of this shrimp, biological and ecological aspects of the established P. macrodactylus in the southern Caspian Sea should be investigated to evaluate any consequences to local communities and/or species.

Biological invasions cause huge environmental and socio-economic losses worldwide. Among successful invaders, there are also several decapod crustacean species. In this study, we report the presence of an potentially invasive crab species that damages rice crops in Sumatra, Indonesia. This paddy-field crab Parathelphusa convexa De Man, 1879 is a freshwater species native to Java, which was introduced in Sumatra around 2000 via an uncertain pathway. The sampling was conducted from July to September 2021 in paddy fields in West Sumatra, where its well-established population was discovered. The crab negatively impacts rice plants and paddy fields in the region through grazing and burrowing behaviour. Since the species is too small to be attractive for human consumption and also, it is not popular for ornamental keeping due to indistinct colouration, it has no benefits for local communities and is considered unwanted. The continuous monitoring of the species with possible regulation or eradication activity in Sumatra is recommended.

Carassius gibelio (Prussian carp) is the latest invader of Canada’s fresh waters, with reports of its presence in Alberta and Saskatchewan. Morphological similarities with introduced C. auratus (goldfish) and the putatively introduced (but likely misidentified) C. carassius (crucian carp) make it difficult to distinguish these species without careful examination. DNA barcoding of the mitochondrial cytochrome c oxidase I (COI) gene is a potential tool to identify Carassius individuals to species, but incorrect annotations of publicly-available sequences can confound attempts at species identification. Here we use morphology and DNA barcoding to identify putative C. gibelio specimens collected from two Alberta locations that constituted new records for the province. Morphologically, specimens were consistent with C. gibelio but were in the range for both C. gibelio and C. auratus. Genetically, our samples could not be identified to species level, being a 100% match with multiple Carassius species. Haplotype networks, however, supported the identification of Alberta carp as C. gibelio, in agreement with statistical analysis. Furthermore, the Alberta haplotype was shared with a fish reported from the seafood trade, suggesting a possible source of entry into Alberta. Therefore, although the BOLD algorithm would suggest the COI gene is not a strong candidate for species-level identification of Carassius species, a haplotype network approach and statistical examination of variability among haplotypes can be used to make reasonable inferences as to species identity. Early detection and management of Carassius species are of critical importance due to their projected ecological impact in Canada; DNA barcoding is one important tool for species identification, especially when specimens are within the phenotypic range expected for multiple species.

Black bullhead Ameiurus melas is a widespread invasive fish in Europe and is considered an ecological and economic threat. Yet, sporadic data are available on its life-history traits. This study assessed the fecundity, growth, and body condition of black bullhead in three oxbows in Hungary. Samples were collected in the resting (October) and pre-spawning (April) periods. Considerable negative allometric growth was observed (b slope ranged between 1.64 and 1.67). The Fulton’s condition factor was lower than any previously reported data (mean = 1.01; SD = 0.09). The mean male: female ratio of the three populations was 1.18:1. Mean absolute fecundity was 3,319 eggs (SD = 1521; range = 1,111–12,727), and mean relative fecundity was 78.8 eggs g^-1 (SD = 21.8; range = 34.8–146.0). The mean oocyte diameter was 0.39 mm in autumn and 0.41 mm in spring. Oocyte size positively correlated with body length. The mean standard length at age was 76.5–81.00 mm at 1+, 126.23–134.35 at 2+, 153–154.5 mm at 3+, and 180–181 mm at 4+. Our results confirmed the phenotypic plasticity of black bullhead out of its native range.

A population of weatherloach has been detected in the Schadgraben stream at Geispolsheim, near Strasbourg (Rhine catchment, eastern France) in autumn 2021 and identified as the European weatherloach Misgurnus fossilis. Another sixty-three weatherloaches were caught in this location the 19 May 2022. The examination of morphological and molecular data on preserved specimens allows to identify this population as the dojo weatherloch Misgurnus anguillicaudatus, an invasive species. The length-weight relationship of this population highlights its good health and establishment. A review of the knowledges about this invasive species is also done. Monitoring must be put in place in order to follow its propagation, threatening native fishes like the endangered M. fossilis.

A specimen of weatherloach was caught in the Lanterne stream at Chevigney-sur-l’Ognon (Rhône catchment, Doubs department, eastern France) on the 22nd of July 2020. It was photographed and initially identified as European weatherloach Misgurnus fossilis before being released. Upon further examination of the photographs, looking at the adipose crests on the caudal peduncle, the coloration pattern and morphometric data of the head, the specimen was then correctly identified as a non-native large-scale loach Misgurnus dabryanus, thus being the first record of this species in France. Monitoring must be put in place to know if there is an established population and to follow its possible propagation.

We provide the first records of threadfin shad (Dorosoma petenense) in the Delaware River estuary, and the first records of this species in the Delaware River basin since they were stocked in a pond but unable to over-winter in 1977. We collected threadfin shad by boat electrofishing on four separate sampling events and in two tributaries to the Delaware River from August 5, 2022, to August 30, 2023. We briefly speculate on the potential impacts of the species, provide mechanisms to explain their occurrence, and discuss our findings in the context of climate warming and range expansion. These records provide the northernmost account of threadfin shad on the eastern seaboard of North America, excluding a questionable record from the Atlantic Ocean near Nova Scotia in November 1998.

The non-native vermiculated sailfin catfish Pterygoplichthys disjunctivus (Weber, 1991) is recorded for the first time in eastern Nepal’s aquatic systems. Native to South America, the first reports of P. disjunctivus in Asia were recorded in India, with subsequent reports from Bangladesh, Hongkong, Indonesia, Malaysia, Singapore, Thailand and Vietnam. Our findings mark the first known occurrence of a non-native species of sailfin catfish in Nepal. The public, policy makers, researchers, and merchants of ornamental fish all need to be informed critically about the release of non-native fish into natural water systems in light of the concerns. Non-native fish may negatively affect native fish populations if released into natural waters. Therefore, it is imperative that strict measures must be taken to prevent the intentional or unintentional escape of non-native fish into Nepal’s natural water systems.