Ambigolimax valentianus (also known as Lehmannia valentiana) is a species of terrestrialslug, a pulmonategastropodmollusc in the family Limacidae. It has spread very widely around the world, especially in greenhouses, where it can be a pest; in warmer climates it has often then spread outdoors. Comparatively much has been learnt about its life cycle and temperature relations. Dissection is necessary to reliably distinguish it from congeners in regions where these co-occur.
External appearance does not reliably distinguish Ambigolimax valentianus from other members of the genus, such as A. parvipenis, with which it may co-occur. Like other members of the Limacidae, it has a pointed tail and the pneumostome lies in the posterior half of the mantle. Often the most obvious character of an Ambigolimax slug is the two parallel, sharply defined, dark lines along the mantle, sometimes with a thicker less well defined line lying between. Two similar lines may lie more posteriorly along the back either side of the midline, but all these lines may be faint or even absent in some individuals. Others have further dots and mottled patches of darker pigment. The dorsal coloration is most often pinkish brown, but sometimes dull yellowish or grey, and all shades inbetween. Older individuals tend to be yellower with less prominent lines but more prominent mottling.[6] The mucus is colourless, transparent, and watery. Maximum length is about 8 cm.[7][3]
Ambigolimax valentianus is identifiable from the internal genitalia, which require dissection to examine. In particular it has a substantial sausage-shaped penial appendage at the inner end of the penis; rarely the appendage is swollen towards its tip.[8] Sometimes the appendage appears absent because it is inverted into the lumen of the penis.[7] This might cause confusion with A. parvipenis but the penis of A. valentianus without the appendage is about as long as the bursa copulatrix and its duct, whereas it is only about half the length in A. parvipenis.[9]
In captivity, at about 17 °C, eggs took roughly 3 weeks to hatch, and hatchlings took about 24 weeks to first lay eggs. These slugs laid of the order of 150 eggs in their lifetimes, but one individual laid 1510 eggs. Eggs were laid in clutches, ranging widely in size but 40 eggs was typical. About half of slugs kept singly had died within 15 months, but some lived for over two years.[10] At 5 °C eggs took much longer to hatch (17 weeks); above 25 °C all eggs died, although a small proportion survived briefer (1 hour) exposures to 31 °C. Hatchlings mostly survived 34 °C, but not 36 °C.[11] However, resistance to heat varies adaptively through the year, as does resistance to cold; in the middle of winter half the individuals could survive −8 °C, whereas for hatchlings in March the equivalent figure was −3 °C.[12]
In subtropical parts of Japan, A. valentianus has an annual life cycle and reproduces during the colder part of the year; egg laying occurs between November and May but is depressed in the coldest months. Sperm is first produced a little earlier during development than eggs. Most eggs hatch in April. In spring two generations of the slug coexist, overlapping in size, before the older generation dies off by June.[6][11] In more temperate parts of Japan, the life cycle is similar, but shifted two months earlier, so that slugs mature already by August or September and die by May. In both populations the trigger for maturation is day length.[13]
Slugs kept singly without the opportunity to mate nevertheless produced as many fertile eggs as those kept in groups.[10] However, population genetic data implies that free-living individuals largely cross with others.[14]
Ambigolimax valentianus eats green leaves and shoots,[6] and consequently can be a pest in greenhouses[15] or even outdoors.[16] It also eats animal matter and fallen leaves.[11] Activity and feeding start before sunset, peaking in the earlier part of the night.[17] This species seldom climbs up trees and during the day is most commonly found under boards, rocks and plant containers.[18][7] Often its first discovery in a country has been in greenhouses, from whence it has spread to gardens, other synanthropic habitats outdoors, and even to woodland, likely facilitated nowadays by global warming.[19][20][7][21] Where it has been introduced, this species may become the dominant slug.[22][18][23] A bizarre consequence of its abundance on Gough Island is that it prevented the eradication of another introduction, the house mouse, by consuming the poison bait dropped from helicopters.[24]
This species has been recorded widely around the world, with its spread starting over 100 years ago.[8] In the following list, oceanic islands are considered separately from the mainland countries to which they belong. If the date of first collection is not given in the cited source, the publication date of the first report is listed instead.
USA: since 1917 (greenhouses); already by 1961 known from California, Colorado, Missouri, Arizona, Oklahoma, New York State, Michigan, Ohio, New Jersey, Massachusetts, Pennsylvania, Kansas, Maryland[8]
Canada: since 1972 (greenhouses, Manitoba), 2000 (outdoors, British Columbia)[54]
Ambigolimax valentianus has been used as a model species for studying the neuromechanisms of learning and memory, particularly by researchers in Japan.[64] Its mucus has been analysed chemically to understand why slug mucus is sticky.[65] Various studies have examined the bacteria and helminth parasites associated with the species.[66][67]
^ abVendetti, J.E.; Burnett, E.; Carlton, L.; Curran, A.T.; Lee, C.; Matsumoto, R.; Mc Donnell, R.; Reich, I.; Willadsen, O. (11 July 2019). "The introduced terrestrial slugs Ambigolimax nyctelius (Bourguignat, 1861) and Ambigolimax valentianus (Férussac, 1821) (Gastropoda: Limacidae) in California, with a discussion of taxonomy, systematics, and discovery by citizen science". Journal of Natural History. 53 (25–26): 1607–1632. doi:10.1080/00222933.2018.1536230. S2CID92483299.
^ abcKanô, Y.; Fukuda, H.; Yoshizaki, H.; Saitô, M.; Hosaka, K.; Sugimura, T.; Itô, Y.F.; Fujiwara, H.; Nakamura, Y.; Mashino, K.; Itô, K.; Tone, K.; Fukuda, T.; Mitoki, T.; Yamashita, H.; Hori, S.; Hori, K.; Hori, H. (2001). "Distribution and seasonal maturation of the alien slug Lehmannia valentiana (Gastropoda: Pulmonata: Limacidae) in Yamaguchi Prefecture, Japan". The Yuriyagi. 8: 1–13.
^ abcdRowson, B.; Turner, J.; Anderson, R.; Symondson, B. (2014). Slugs of Britain & Ireland: identification, understanding and control (First ed.). Telford. ISBN978-1908819130.{{cite book}}: CS1 maint: location missing publisher (link)
^ abcdefghijklmnopWaldén, H.W. (1961). "On the variation, nomenclature, distribution and taxonomical position of Limax (Lehmannia) valentianus Férussac (Gastropoda, Pulmonata)". Arkiv för Zoologi. 15: 71–95.
^ abcHutchinson, J.M.C.; Reise, H.; Schlitt, B. (30 June 2022). "Will the real Limax nyctelius please step forward: Lehmannia, Ambigolimax, or Malacolimax? No, Letourneuxia!". Archiv für Molluskenkunde. 151 (1): 19–41. doi:10.1127/arch.moll/151/019-041. S2CID250188836.
^ abcUdaka, H.; Mori, M.; Goto, S.G.; Numata, H. (September 2007). "Seasonal reproductive cycle in relation to tolerance to high temperatures in the terrestrial slug Lehmannia valentiana". Invertebrate Biology. 126 (2): 154–162. doi:10.1111/j.1744-7410.2007.00085.x.
^ abUdaka, H.; Numata, H. (September 2010). "Comparison of the life cycle and photoperiodic response between northern and southern populations of the terrestrial slug Lehmannia valentiana in Japan". Zoological Science. 27 (9): 735–739. doi:10.2108/zsj.27.735. PMID20822401. S2CID22274009.
^von Proschwitz, T. (2020). "Faunistical news from the Göteborg Natural History Museum 2019 – snails, slugs and mussels". Göteborgs Naturhistoriska Museum Årstryck. 2020: 33–48.
^Van Goethem, J.L. (1976). "Contribution à l'étude de Lehmannia valentiana (de Férussac, 1821) (Mollusca, Pulmonata, Limacidae)". Bulletin van het Koninklijk Belgisch Instituut voor Natuurwetenschappen, Biologie. 51 (5): 1-14, pl. 1.
^Gittenberger, E.; de Winter, A.J. (1980). "Nieuwe gegevens over in Nederland gevonden naaktslakken". Basteria. 44 (5/6): 71–76.
^Olsen, K.M. "Landsnegler i Norge — en oppsummering of en presentasjon av tre nye arter, Oxychilus navarricus (Bourguignat, 1870), Lucilla singleyana (Pilsbry, 1890) og Hawaiia minuscula (Binney, 1840)". Fauna. 55 (2): 66–77.
^Koivunen, A.; Malinen, P.; Ormio, H.; Terhivuo, J.; Valovirta, I. (2014). Suomen kotilot ja etanat : opas maanilviäisten maailmaan. Helsinki: Hyönteistarvike Tibiale Oy. ISBN9789526754468.
^Turner, H.; Kuiper, J.G.J.; Thew, N.; Bernasconi, R.; Rüetschi, J.; Wüthrich, M.; Gosteli, M. (1998). Atlas der Mollusken der Schweiz und Liechtensteins. Fauna Hevetica 2. Neuchâtel: Centre suisse de cartographie de la faune; Schweizerische Entomologische Gesellschaft. ISBN2884140131.
^Beckmann, K.-H. (2003). "Neunachweis von Lehmannia valentiana für die Maltesischen Inseln". Heldia. 5 (1/2): 37.
^Flasar, I. "Limax (Lehmannia) valentianus Férussac v Československu (Gastropoda, Pulmonata)". Časopis Národního Muzea, Oddíl přírodovědný. 133 (1): 42–45.
^Reischutz, P.L. "Beiträge zur Molluskenfauna des Waldviertels". In Prihoda, I. (ed.). Festschrift zur 50-Jahr-Feier des Höbarthmuseum und Museumvereins in Horn 1930–1980. Horn: Museumverein. pp. 259–275.
^Grossu, A.V.; Lupu, D. (1962). "Zur Kenntnis der Gattung Lehmannia Heynemann (Limacidae) und deren große Variabilität, nebst Beschreibung neuer Arten". Archiv für Molluskenkunde. 91 (4/6): 191–201.
^ abLikharev, I.M.; Wiktor, A.J. (1980). Slizni fauny SSSR i sopredel'nykh stran (Gastropoda terrestria nuda). [The fauna of slugs of the USSR and adjacent countries (Gastropoda terrestria nuda).] Fauna SSSR (Novaja serija 122) Molljuskii 3 (5). Leningrad: Akademii Nauk SSSR, Zoologicheskii Institut.
^Norris, A. (1986). "Distributional records of land molluscs from southern Morocco". Journal of Conchology. 32 (4): 259–260.
^Eki̇n, İ.; Şeşen, R. (26 July 2018). "A new record of three-band garden slug Ambigolimax valentianus (A. Férussac, 1822) (Gastropoda: Limacidae) from Turkey". Turkish Journal of Zoology. 42 (4): 475–479. doi:10.3906/zoo-1712-34. hdl:11503/878. S2CID92474823.
^Vaisman, S.; Mienis, H.K. (2015). "Molluscs intercepted at the borders of Israel in 2014". Tentacle. 23: 12–13.
^Shileiyko, A. A.; Rymzhanov, T.S. (2013). Fauna of land mollusks (Gastropoda, Pulmonata terrestria) of Kazakhstan and adjacent territories. Moscow: KMK Scientific Press. ISBN9785873179022.
^Ahmadi, E. (2004). "Biology of Lehmannia valentiana (Ferussac, 1823) in Mahallat [In Persian]". Journal of Agriculture. 6 (1): 1–8.
^Wiktor A., De-niu C. & Wu M. (2000). "Stylommatophoran slugs of China (Gastropoda: Pulmonata) – prodromus". Folia Malacologica 8(1): 3-35.
^Yap, E.H.; Tan, S.K. (2021). "Biodiversity Record: The three-band garden slug, Ambigolimax valentianus, in Singapore". Nature in Singapore. 14: 12. doi:10.26107/NIS-2021-0012.
^Naranjo-García, E.; Castillo-Rodríguez, Z.G. (2017). "First inventory of the introduced and invasive mollusks in Mexico". The Nautilus. 131 (2): 107–126.
^Fernández de Valera, J. (1982). "Contribución al conocimiento de las babosas y sietecueros (Mollusca: Gastropoda) que causan daños a la agricultura en Venezuela". Revista de la Facultad de Agronomía (Maracay). 7: 353–386.
^Simone, L.R. L.de (2006). Land and freshwater molluscs of Brazil : an illustrated inventory on the Brazilian malacofauna, including neighbor regions of the South America, respect to the terrestrial and freshwater ecosystems. São Paulo, Brazil: Museu de Zoologia, Universidade de São Paulo. ISBN8590667006.
^Waldén, H.W. (1983). "Systematic and biogeographical studies of the terrestrial Gastropoda of Madeira. With an annotated Check-list". Annales Zoologici Fennici. 20 (4): 255–275. JSTOR23734277.
^ abPreece, R.C. (2001). "Introduced land molluscs on the islands of the Tristan da Cunha - Gough group (South Atlantic)". Journal of Conchology. 37 (3): 253–259.
^Hayes, K.A.; Yeung, N.W.; Kim, J.R.; Cowie, R.H. (2012). "New records of alien Gastropoda in the Hawaiian Islands: 1996–2010". Bishop Museum Occasional Papers. 112: 21–28.
^Kimura, K.; Saito, T.; Chiba, S.; Pak, J.-H. (30 July 2019). "An updated checklist of land and freshwater gastropod fauna on Ulleung Island, South Korea". American Malacological Bulletin. 37 (1): 35. doi:10.4003/006.037.0104. S2CID201211811.
^Brophy, T.; Mc Donnell, R.J.; Howe, D.K.; Denver, D.R.; Ross, J.L.; Luong, L.T. (2020). "Nematodes associated with terrestrial slugs in the Edmonton region of Alberta, Canada". Journal of Helminthology. 94: e200. doi:10.1017/S0022149X20000838. PMID33046147. S2CID222320173.