Three New Alien Taxa for Europe and a Chorological Update on the Alien Vascular Flora of Calabria (Southern Italy)

Knowledge on alien species is needed nowadays to protect natural habitats and prevent ecological damage. The presence of new alien plant species in Italy is increasing every day. Calabria, its southernmost region, is not yet well known with regard to this aspect. Thanks to fieldwork, sampling, and observing many exotic plants in Calabria, here, we report new data on 34 alien taxa. In particular, we found three new taxa for Europe (Cascabela thevetia, Ipomoea setosa subsp. pavonii, and Tecoma stans), three new for Italy (Brugmansia aurea, Narcissus ‘Cotinga’, and Narcissus ‘Erlicheer’), one new one for the Italian Peninsula (Luffa aegyptiaca), and 21 new taxa for Calabria (Allium cepa, Asparagus setaceus, Bassia scoparia, Beta vulgaris subsp. vulgaris, Bidens formosa, Casuarina equisetifolia, Cedrus atlantica, Chlorophytum comosum, Cucurbita maxima subsp. maxima, Dolichandra unguis-cati, Fagopyrum esculentum, Freesia alba, Juglans regia, Kalanchoë delagoënsis, Passiflora caerulea, Portulaca grandiflora, Prunus armeniaca, Prunus dulcis, Solanum tuberosum, Tradescantia sillamontana, and Washingtonia filifera). Furthermore, we provide the first geolocalized record of Araujia sericifera, the confirmation of Oxalis stricta, and propose a change of status for four taxa (Cenchrus setaceus, Salpichroa origanifolia, Sesbania punicea, and Nothoscordum gracile) for Calabria. The updated knowledge on the presence of new alien species in Calabria, in Italy and in Europe could allow for the prevention of other new entries and to eliminate this potential ecological threat to natural habitats.


Introduction
The increase in alien plant invasion represents a very significant ecological problem for native flora [1]. This produces several impacts around the world such as the reduction of native and endemic species and habitats, but also damage to socio-economic and human health [2][3][4][5][6]. For example, R. pseudocacia L. has several effects on the endangered lichen species Lobaria pulmonaria (L.) Hoffm. (loss of diversity, among others) that are also due to climate change [7][8][9]. Thanks to a recent work, several invasive alien species were assessed in Italian regions [10]: in Toscana, Carpobrotus acinaciformis (L.)

Results
In this research work, we report 34 alien taxa recorded in several places of Calabria with different status of invasiveness ( Figure 2; Table 1; Appendix A). Among these, three taxa are new for Europe

Discussion
The continuous and constant increase in a short time of new records of alien taxa in the Calabrian territory, and generally in Italy and Europe, represents a worrying threat for the autochthonous biodiversity and a clear sign of the ongoing climate change [55].
As shown in Figure 1, most of the new reports of alien taxa occurred within inhabited areas; these have a high risk of future invasion of natural habitats [56]. A total of 85% of recorded taxa is "casual", 3% "naturalized", and 12% is "invasive". This last percentage of invasive taxa comes from a change of status that we propose in the present work, which means that several taxa continue to expand their range of distribution, representing a constant threat for native species and habitats.
Several records have been found along roadsides ( Figure 3). Indeed, roadsides are places where alien taxa can establish [57,58] and are a considerable way to invade other areas [59]. Obviously, roads were also the places traveled by us during our research as it is more common to find new alien taxa along them. This does not mean that other habitats are not good places for alien taxa: in fact, numerous taxa have been encountered in other habitats but not considered here because they have already been reported previously for Calabria. In this study, we found that, out of 118 records, 60% were found along roadsides ( Figure 3)! Only 8% were found in sidewalks and in temporary water bodies such as drainage channels and fiumare (typical rivers of southern Italy with torrential and irregular regime.), 7% in uncultivated fields, 5% in crop habitats, and 12% in other habitats (outcropping rocks, walls, shrublands and ruins). More details are reported in Table 2.

Discussion
The continuous and constant increase in a short time of new records of alien taxa in the Calabrian territory, and generally in Italy and Europe, represents a worrying threat for the autochthonous biodiversity and a clear sign of the ongoing climate change [55].
As shown in Figure 1, most of the new reports of alien taxa occurred within inhabited areas; these have a high risk of future invasion of natural habitats [56]. A total of 85% of recorded taxa is "casual", 3% "naturalized", and 12% is "invasive". This last percentage of invasive taxa comes from a change of status that we propose in the present work, which means that several taxa continue to expand their range of distribution, representing a constant threat for native species and habitats.
Several records have been found along roadsides ( Figure 3). Indeed, roadsides are places where alien taxa can establish [57,58] and are a considerable way to invade other areas [59]. Obviously, roads were also the places traveled by us during our research as it is more common to find new alien taxa along them. This does not mean that other habitats are not good places for alien taxa: in fact, numerous taxa have been encountered in other habitats but not considered here because they have already been reported previously for Calabria. In this study, we found that, out of 118 records, 60% were found along roadsides ( Figure 3)! Only 8% were found in sidewalks and in temporary water bodies such as drainage channels and fiumare (typical rivers of southern Italy with torrential and irregular regime.), 7% in uncultivated fields, 5% in crop habitats, and 12% in other habitats (outcropping rocks, walls, shrublands and ruins). More details are reported in Table 2.    We verified the distribution of taxa within the Natura 2000 network. Some taxa grew in network sites: Beta vulgaris subsp. vulgaris, Cedrus atlantica, Fagopyrum esculentum, Freesia alba, Juglans regia, and Nothoscordum gracile (Table 3). B. vulgaris subsp. vulgaris was found in SAC IT9350145 "Fiumara Amendolea (including Roghudi, Chorio, and Rota Greco)" and in SPA IT9350300 "Costa Viola", while C. atlantica, F. esculentum, F. alba, J. regia, and N. gracile were only found in the SPA IT9350300 "Costa Viola". If C. atlantica, F. esculentum, F. alba, and J. regia are considered as "casual", B. vulgaris subsp. vulgaris tends to naturalize, and N. gracile becomes invasive in other sites where it has been found, also representing a potential threat for protected areas such as SPA "Costa Viola". Two species (Araujia sericifera and Washingtonia filifera) are recently included in a list of candidate species to be submitted to the national prioritization procedure for their inclusion in a national list according to Regulation (EU) No. 1143/2014 [62]. Therefore, knowledge of new sites of A. sericifera and the new record of W. filifera for Calabria are very important for their control because they have a detrimental impact on plant communities [63].
Among others, Cenchrus setaceus is rapidly spreading in the regional territory after its first report in 2007 [64]. Indeed, these authors reported C. setaceus (sub Pennisetum setaceum) for Calabria in two locations, both along communication routes, but at a high distance from each other: one along the A2 motorway between Rosarno and Gioia Tauro in the province of Reggio Calabria on the Thyerrenian side, and another along highway SS 106 Jonica near Cropani Marina in the province of Catanzaro on the Ionian side of the region. After several new records of this alien species for Calabria by Musarella et al. [44,50] [44]. According to Brundu [65], only an early detection and rapid eradication (EDRE) of C. setaceus can prevent its rapid spread, for this reason, its continuous monitoring is really important to prevent ecological damage.
Two cultivars of Narcissus used as ornamentals were observed by the authors ( Figure A1). Report no. 21 was recorded for two locations where it has multiplied over the years after the first observation in 2013 by Laface and report no. 22 was recorded for the first time at the beginning of 2020 by Musarella. It is likely that they escaped cultivation or were thrown among the waste material from nearby gardens. As to which cultivars they were, there are more than 27,000 daffodils of garden origin registered in the International Daffodil Register and Classified List in 2008 [66]. According to [66], the report no. 21, which has single flowers with solitary flowers, white reflexed perianth segments and an apricot-pink corona, belongs in Division 6 (Cyclamineus) and was recognized as Narcissus 'Cotinga'. Report no. 22, Plants 2020, 9, 1181 9 of 31 which has double flowers with white perianth segments with a trace of yellow at the base, belongs to Division 4 (Double flowered) and is referred to as Narcissus 'Erlicheer'. Regarding their invasiveness, it is important to consider that daffodils rarely spread rapidly and certainly the Division 4 cultivars are sterile, so cannot spread by seed. For this reason, we consider it to not have a detrimental impact on the environment. These are both first records for Italy.

Materials and Methods
This research was based on fieldwork carried out randomly and during a well-designed research field for the coordination of monitoring activities of natural and semi-natural habitats of the flora and fauna species of the Natura 2000 Network present in Calabria (see Funding section) from 2018 to 2020 as well as on herbaria and literature surveys. As part of this project, in fact, it was necessary to verify the conservation status of the habitats in accordance with the European Directive [60] as well as in relation to the possible threat or pressure exerted by an alien species on them. Fieldwork consisted of collecting samples of alien plants and identifying them in the laboratory. The collected specimens was stored dried in the herbarium of the Mediterranean University of Reggio Calabria (Italy) (REGGIO, acronym according to Thiers [67]). The investigated area was the whole of Calabria, but the new records concern only the central-southern part.

Conclusions
Although there is adequate knowledge of the alien flora in Italy, not much is known about those in Calabria thus far. As before indicated, Calabrian alien vascular flora amounts to 344 taxa [53,54]. Thanks to this study, it was possible to increase this knowledge by reporting new data on 34 taxa: one (1) confirmation for Calabria, some new for Calabria (21), other new for the Italian Peninsula (1), three (3) for the whole of Italy, and three (3) new for the whole of Europe. Furthermore, a georeferenced location for Araujia sericifera (1) and the invasiveness status for four (4) species already known for the region are reported here for the first time. In total, 28 taxa are new to Calabria. Therefore, we can currently count 373 alien plant taxa for the whole of Calabria. This was possible thanks to the increasing attention to the exotic taxa introduced because, compared to the past, these taxa are invading more and more indigenous habitats, compromising their ecological balance and threatening the survival of native taxa. Works like these are very important because they provide the possibility of identifying a large number of new alien plant species that are spreading worldwide, allowing us to fill in the many gaps at the regional, national and global level.
Nonetheless, it is now clear that knowledge of native species is not enough for the protection of a specific territory. Of additional importance is the knowledge of alien species, their invasive potential, prevention in their introduction (both intentional and accidental), and their immediate eradication (i.e., Cenchrus setaceus, Nothoscordum gracile, Salpichroa origanifolia, and Sesbania punicea, which are spreading very rapidly as invasives). All these actions must be carried out by both the public and private institutions responsible for this, and most notably by citizens that can responsibly act autonomously in this sense. However, the ever-increasing diffusion of taxonomic, biological and ecological knowledge must form the basis for carrying out sustainable policies for the environment.
Supplementary Materials: The following are available online at http://www.mdpi.com/2223-7747/9/9/1181/s1, Table S1: Details of all 118 new records. Calabria, this species was indicated as "recently not confirmed" by Celesti-Grapow et al. [87] and Galasso et al. [1], whereas was recently reported by Musarella et al. [44] for the same locality of Catona as casual, but in an unspecified uncultivated field. Recently, Lazzaro et al. [62] proposed this species for its inclusion in a national list of invasive species according to EU Regulation 1143/2014 [88]. Note. Widely used as an ornamental plant, particularly appreciated for the creation of low hedges, it is probably escaped from plants grown in pots or from nearby flowerbeds (observed by Musarella). B. scoparia is present throughout Italy as invasive, naturalized, or casual alien and not reported only for Molise and Basilicata [1]. Note. B. vulgaris subsp. vulgaris is cultivated throughout Italy for food purposes. It grows abundantly in uncultivated and cultivated fields, in abandoned lands and on the edges of country roads. The subspecies is considered as a casual alien throughout Italy [1]. Several records above reported are known by Laface since about twenty years for their own domestic food uses. Note. Cultivated for ornamental purposes, very fragrant trumpet-shaped flowers, this plant is very attractive to bees, butterflies, and birds. Two plants were recorded along the road, mixed with Opuntia ficus-indica (L.) Mill. and Oxalis pes-caprae L. (Appendix B, Figure A2). In Europe, B. aurea was recorded only in Spain [89], therefore, this is the second report for Europe and the first for Italy. Note. C. thevetia is an evergreen shrub native to tropical America (Mexico, Central America (Guatemala, Belize, El Salvador, Honduras, Nicaragua, Costa Rica, and Panama), South America (Colombia, Venezuela, British Guiana, Brazil, Ecuador, Peru, and Bolivia) and cultivated in the Antilles (Bahamas, Cuba, Haiti, Jamaica, Puerto Rico, and Dominican Republic), but it is widespread in the tropics around the world [90]. It is commonly cultivated as an ornamental plant and its flowering occurs throughout the year. Numerous seedlings have been found, born from seeds, in a water drainage channel and some adult plants along a wall, on the side of a typical little river ("fiumara"), mixed with Phyllostcahys aurea Carrière ex Rivière and C. Rivière (Appendix B, Figure A3). In Europe, it is reported as doubtful for Cyprus [91] and a preserved specimen is recorded for Portugal, but without a certain locality [92]. However, according to [83,84], C. thevetia is not given as present in Cyprus. Therefore, our finding represents the first European record. Note. The plants observed were certainly generated by the seeds of some trees nearby planted, accidentally blown into the cracks in the walls (Appendix B, Figure A4). According to Galasso et al. [1], in Italy, this species is a casual alien in Lazio, Sicilia, Campania, and naturalized in Puglia and Toscana. Note. According to Galasso et al. [1], in Italy, this species is a casual alien only in Sicilia and Basilicata. Note. C. setaceus is one of the "black" species present in the "Union list" of the European Union [86]. In Italy, this species is a casual alien in Calabria, Lazio, and Toscana, naturalized in Puglia, and invasive in Sardegna and Sicilia [1]. Subsequently, Musarella et al. [44] reported it as naturalized in Calabria. The specimens collected (S.S. 106 Occhio di Pellaro and Saline Joniche) along some city streets (Appendix B, Figure A5) probably come from some nearby villas or other spontaneous individuals geographically close. The new records reported here previously had not been observed by the authors, which means that they were born less than a year after previous reports by Musarella et al. [44].
Reported for the first time in Calabria in 2007 [64], the species shows (as in other Italian regions) a strongly invasive character. C. setaceus was initially reported for this region by Celesti-Grapow et al. [87] and then confirmed by Musarella et al. [49] as casual. Recently, it was recorded as naturalized, according to Musarella et al. [44], but this species continues its uncontrollable expansion in Calabria and can therefore be considered as invasive. Note. C. maxima is locally cultivated for food purposes. Some flowering plants have been observed near water sources, likely to have escaped cultivation from nearby vegetable gardens. According to Galasso et al. [1], this subspecies is considered as a casual alien in northern Italy, in some regions of central Italy, and on the islands. Note. Few plants were recorded along a road, mixed with Amaranthus sp. and Setaria sp., probably escaped from the cultivation of nearby gardens or vegetable gardens. In Italy, it is present in many regions as a casual alien (Abruzzo, Campania, Emilia-Romagna, Friuli Venezia Giulia, Lazio, Lombardia, Piemonte, Puglia, Trentino-Alto Adige, Umbria, and Veneto), whereas in Toscana it is naturalized [1]. In it, the authors describe 425 taxa of Ipomoea and provide an identification key. According to these authors, the collected specimen from Rizziconi belong to I. setosa subsp. pavonii, a new recognized subspecies (comb. et stat. nov.). This subspecies is native to South America and it has fleshy trichomes on peduncles and pedicels, and these last are strongly swollen below the calyx. Its flowers have a short corolla of 5-6.5 cm [81]. Some details of the plants collected in Calabria are presented in Figure A6 of Figure A7). In Italy, based on Galasso et al. [1], J. regia is present as naturalized in almost all regions of the Italian Peninsula or as cryptogenic in Sardegna, Lombardia, and Veneto, whereas it is absent only in Puglia. In Calabria, its use is known not only for their fruits as food but also for their leaves as an emollient for excessive feet perspiration [33,35] or to treat warts [34]. Note. Some plants have been observed on roadsides, probably originating from some nearby pots where the plant is grown. According to Galasso et al. [1], this species is present as a casual alien in Sicilia, Sardegna, Lazio, and Puglia. Note. Several plants have been found occupying a large part of the river ("fiumara") and almost completely covered the vegetation below, characterized mainly by shrubs of Tamarix africana Poir (Appendix B, Figure A8). Based on Galasso et al. [1], L. aegyptiaca is present exclusively in Sicilia as a casual alien, therefore, this is the first report for Calabria and the Italian Peninsula. Note. N. gracile has been observed growing in the crevices of sidewalks, probably escaped from nearby pots or flower beds. In Italy, it is present as naturalized in Campania, Toscana, and Puglia and as a casual alien in Liguria, Piemonte, and Sardegna [1]. N. gracile was recently reported in Calabria by Rosati et al. [52] as casual in Lazzaro (Reggio Calabria province). In several locations reported here in Specimina (and in particular in Lazzaro), this species has spread everywhere, especially along the edges of the streets. Therefore, due to its rapid spread, we propose here the new status of invasive. Note. O. stricta grows in the crevices of the walls and sidewalks. It was probably introduced through nurseries or horticultural material. This species is naturalized or invasive in northern Italy and in some regions of central Italy, whereas it is reported as doubtful for Calabria [1]. Our record confirms its presence in the region. Note. Fruit tree cultivated mainly for the production of almonds, P. dulcis is used as food and in the confectionery industry. The species spreads rapidly by seed; all plants found were grown near almond groves nearby. According to Galasso et al. [1], this species is a casual alien throughout Italy excluding Lombardia, Valle d'Aosta, and Puglia where the species is naturalized. Note. Recently reported as naturalized for Calabria in the province of Cosenza in 2015 [94], this is the second record for the region of S. punicea. This alien species shows a high degree of invasiveness in the new locality; it occupies more or less 100 m in length of a narrow water drainage channel along a road. The plants found were flowering and fruiting and several seedlings were also growing (Appendix B, Figure A9). For this reason, due to its rapid widespread and continuous reproduction, we propose the new status of invasive. Note. Native to southern USA, Mexico, the Caribbean, Peru, and Ecuador [93]. The dispersion occurs mainly through winged seeds dispersed by the wind, produced in large quantities almost all year round [95,96]. The plant observed probably originates from seeds of nearby houses, grown in the cracks of the sidewalk near a high traffic state road (Appendix B, Figure A10). Widely spread worldwide, T. stans is reported in Europe only for Malta as T. stans var. sambucifolia [97], whereas it is not given as present in Malta according to Euro+Med PlantBase [83]. Therefore, we consider this as the first report for Europe. Note. Succulent species cultivated as an ornamental plant for its characteristic "hairy" leaves, it reproduces easily by vegetative way, and the plant probably escaped the cultivation from the nearby villas, after being thrown together with waste material (Appendix B, Figure A11). After the first record for Italy in Campania [98], this is the second one for the country and the first for Calabria. Note. Several individuals were found along a sidewalk. The seeds that are highly appetizing to birds are transported even at great distances. W. filifera has no particular ecological needs; it adapts easily to growing even in unfavorable conditions and is often found in the cracks in the walls and sidewalks. In Italy, based on Galasso et al. [1], the species is a casual alien in Abruzzo, Campania, Liguria, Puglia, Sardegna, and is naturalized in Sicilia. Recently, Lazzaro et al. [60] proposed this species for its inclusion on a national list of invasive species according to Regulation (EU) No. 1143/2014.

Appendix B
First record for Calabria (casual) Specimen: 10 January 2020, lungo la strada tra i dipartimenti di Agraria e di Ingegneria (Reggio Calabria province), sidewalk, 38.120043°N-15.666549°E, 85 m a.s.l., leg. et det. V.L.A. Laface (REGGIO). Note. Several individuals were found along a sidewalk. The seeds that are highly appetizing to birds are transported even at great distances. W. filifera has no particular ecological needs; it adapts easily to growing even in unfavorable conditions and is often found in the cracks in the walls and sidewalks. In Italy, based on Galasso et al. [1], the species is a casual alien in Abruzzo, Campania, Liguria, Puglia, Sardegna, and is naturalized in Sicilia. Recently, Lazzaro et al. [60] proposed this species for its inclusion on a national list of invasive species according to Regulation (EU) No. 1143/2014.