J.M.C. HUTCHINSON, H. REISE & D.G. ROBINSON 2014. A biography of an invasive terrestrial slug: the spread, distribution and habitat of Deroceras invadens. Neobiota 23: 17–64.

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Our 2020 article utilises sequence variation in the barcoding portion of COI to elucidate further details of the origin and spread of D. invadens. We have shown that the area of origin was centered on the southern part of mainland Italy and the adjacent part of Sicily; here genetic diversity is much higher, with the variation structured geographically. There are indications that the species was also distributed in parts of central Italy but more restricted than today. In Australia and North America, the rarity or absence of haplotypes common in Europe suggests that import controls have some effect. The California population is genetically distinct from that in British Columbia, and the Newfoundland occurrence is different again. The California population has seeded populations across N. America, but not elsewhere. Within Europe multiple colonisations of new areas has probably kept genetic diversity high.

At the time of writing we were unable to access, Brault, J.P. & Gervais, M. 2004. Les mollusques du LOIR-ET-CHER. Romoranin-Lantheray: Parc Beauvais. In this department in central FRANCE they found D. invadens in 7 grid squares, compared with 36 for D. reticulatum (ratio = 0.19).

The tetrad (2✕2 km) survey of OXFORDSHIRE (Gregory, S.J., Northmoor Trust & Campbell, J.M. 2000. An atlas of Oxfordshire terrestrial Mollusca. Standlake, UK: Oxfordshire Museums) found D. invadens in 92 squares from 1985–2000 in comparison with 437 for D. reticulatum (ratio = 0.21). It is described as "fairly common ... throughout ... possibly continues to increase ... disturbed sites".

We overlooked that a single locality (in the village of Aixovall) for D. invadens was included in an atlas of ANDORRA: Bertran, A. 2000. Les mollusques d'Andorre: atlas préliminaire de repartition. Documents Malacologiques 1: 17–39. Nevertheless the species was not mentioned in the more recent guide to Andorra: Borredà, V., Martínez-Ortí, A. & Nicolau, J. 2010. Guia de camp dels mol·luscs d'Andorra. Andorra: Centre d’Estudis de la Neu i de la Muntanya d’Andorra.

We overlooked the following article which provides records for D. invadens (or possibly D. panormitanum: see notes on Portugal below) in Extremadura, W. SPAIN: Bech i Taberner, M., Rodríguez López, M.T., Ondina Navarret, M.P. & Altimiras i Roset, J. 2005. Nuevas aportaciones al conocimiento de los moluscos actuales y del cuaternario en Extremadura. II. Malacofauna terrestre (babosas). Revista de estudios extremeños 61(2): 813–836. Deroceras invadens was found in 3 10 km squares (compared with 20 for D. reticulatum: ratio = 0.17)

The recent discovery of D. invadens in ISRAEL, the first record for Asia, was published too late to be included in our article. It turned up in a garden centre in 2013.
Mienis, H.K., Mienis, D, Vaisman, S & Rittner, O. 2014. Two exotic gastropods: Aegopinella nitidula and Deroceras invadens, recently discovered in Israel. Triton 29: 21–25.
The species has since been found in further nurseries and garden centres in Israel: Mienis, H.K. & Rittner, O. 2015. Malacological fieldwork in Israel. In: The Steinhardt Museum of Natural History. Israel National Center for Biodiversity Studies. Annual Report 2013/2014, pp. 70–87. Tel Aviv University, Tel Aviv.

In 2015 D. invadens was found on cabbage being imported into ISRAEL from the Netherlands: 23,100 kg of cabbage was sent back! It has been found twice more on potted plants arriving in Israel from the Netherlands.
Vaisman, S. & Mienis, H.K. 2016. Molluscs intercepted at the borders of Israel in 2014 (additional records) and 2015. Tentacle 24: 16–17.
Vaisman, S. & Mienis, H.K. 2018. Molluscs intercepted at the borders of Israel in 2017. Tentacle 26: 14–15.

Deroceras invadens was recorded from a rubbish dump at the edge of the town of Tivat in MONTENEGRO in October 2014. This is only the second record from the Balkan Peninsula, after the one from Crete. The population was mixed with D. sturanyi.
Soes, M. 2014. The first record of Deroceras invadens (Gastropoda: Pulmonata: Agriolimacidae) for Montenegro. Ecologica Montenegrina 1: 189–190.

In August 2014 we collected D. invadens from a flower border in Vaduz, LIECHTENSTEIN, the first record for this country. This is now published in our 2020 article together with a 2017 record from LA GOMERA in the Canaries.

Deroceras invadens was found on NORFOLK ISLAND in the Pacific in 2013 (in a greenhouse, under timber, and amongst coastal weeds and debris):
Colgan, D.J. (2017) The invasive slug Deroceras invadens Reise, Hutchinson, Schunack and Schlitt, 2011 occurs on Norfolk Island. Bioinvasions Records 6: 9–12.

The new handbook of terrestrial molluscs in FINLAND describes D. invadens as mostly in greenhouses but also now in the wild ("mutta selviää myös luonnossa"):
Koivunen, A., Malinen, P., Ormio, H., Terhivuo, J. & Valovirta, I. 2014. Suomen kotilot ja etana: opas maanilviäisten maailmaan. Helsinki: Hyönteistarvike Tibiale Oy.

Schikov mentions D. pollonerae (a synonym of D. invadens) from greenhouses in the Tver region of European RUSSIA from 2009.
Schikov, E.V. (2016) Adventive species of terrestrial malacofauna in the central portion of the Russian plain [In Russian]. Ruthenica 26(3–4): 153–164.

Deroceras invadens has been recorded outdoors in SLOVAKIA, in 2017 from a garden centre in Bratislava and in 2018 from a back garden in the town of Stupava, 14 km to the north. This record is now published in
Čejka T. et al. 2020. Malacological news from the Czech and Slovak Republics in 2015–2019. Malacologica Bohemoslovaca 19: 71–106.
together with a couple of additional records from the CZECH REPUBLIC (where we also found it in Frydlant in 2019).

Our own paper reports Deroceras invadens from several POLISH towns adjacent to the German border near Görlitz, but interestingly not from towns further away:
Hutchinson, J.M.C. & Reise, H. 2015. An invasion from Germany; Deroceras invadens (Pulmonata, Agriolimacidae) and other synanthropic slugs in the southwest corner of Poland. Folia Malacologica 23: 301–307.

This looks like a convincing 2017 record from FLORIDA. We have recently (2020) found D. invadens also in a garden centre in Tucson, ARIZONA.

A published record for D. invadens in the far east of British Columbia, CANADA, turns out to be based only on external characters (K. Ovaska pers. comm.), so should be considered unconfirmed: Ovaska, K. et al. 2019. Surveys for terrestrial gastropods in the Kootenay region of British Columbia, with new records and range extensions. Canadian Field-Naturalist 133(3): 221–234.

This article provides a few further records from MEXICO, interesting because of the diversity of habitats: “in the urban zone of Mexico City, a highly polluted rural area in Tlaxcala, and a natural pine forest in Hidalgo”.
Araiza-Gòmez, V., Naranjo-García, E. & Zúñiga, G. (2017)
The exotic slugs of the genus Deroceras (Agriolimacidae) in Mexico: Morphological and molecular characterization, and new data on their distribution. American Malacological Bulletin 35: 126–133.

Collections lent to us by David Holyoak prove that D. panormitanum s.s. was present in mainland PORTUGAL by 2013. (D. invadens is also present.) This is now cited in: Holyoak, D.T., Holyoak, G.A. & Mendes R.M. da Costa (2019) A revised check-list of the land and freshwater Mollusca (Gastropoda and Bivalvia) of mainland Portugal. Iberus 37: 113–168.


A more careful reading of Gutiérrez Gregoric et al. (2013) would have revealed that the collections of D. invadens in Argentina originate from 2004, not 2010 and 2011: our interpretation of the museum catalogue was incorrect. So 2004 is the date of first discovery in ARGENTINA.

Ted von Proschwitz has kindly pointed out that the locality “Bysek” mentioned in the section on Sweden (p. 32) should read “Byske”.

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