Naturalised terrestrial Stylommatophora (Mollusca: Gastropoda)

Abstract

The naturalised terrestrial gastropod fauna of New Zealand is shown to comprise a total of 29 species representing 11 stylommatophoran families. Taxa previously recognised in New Zealand's naturalised fauna and confirmed in this study are (with recommended common names): Agriolimacidae - Deroceras laeve (marsh slug), D. panormitanum (brown field slug), D . reticulatum (grey field slug); Arionidae - Arion hortensis (Ferussac's orange soled slug), A. intermedius (glade slug); Cochlicopidae - Cochlicopa lubrica (slippery moss snail); Ferussaciidae - Cecilioides acicula (blind pin snail); Helicidae - Cantareus aspersus (brown garden snail); Hygromiidae - Candidula intersecta (wrinkled snail); Limacidae - Lehmannia nyctelia (Bourguignat's slug), Limacus flavus (yellow cellar slug), Limax maximus (tiger slug); Milacidae - Milax gagates (jet slug), Tandonia budapestensis (Budapest slug), T. sowerbyi (Sowerby's slug); Pupillidae - Lauria cylindracea (chrysalis snail); Testacellidae - Testacella haliotidea (shelled slug); Valloniidae - Vallonia excentrica (eccentric grass snail); Vertiginidae - Vertigo ovata (grassland whorl snail); Zonitidae - Oxychilus alliarius (garlic glass snail), O. cellarius (cellar glass snail), O. draparnaudi (Drapamaud's glass snail), Vitrea crystallina (crystal snail). Consistent with recent revisions, several generic-species epithet combinations are applied for the first time to the New Zealand naturalised fauna: these include Cantareus aspersus (formerly in genus Helix ); Limacus flavus (formerly in Limax ( Limacus ) or Lehmannia ); Tandonia budapestensis and T. sowerbyi (formerly Milax ). Arion distinctus (Arionidae) (Mabille's orange soled slug) is shown to have been long established and widespread in New Zealand, but previously not recognised as a component of A. hortensis s.l. Zonitoides arboreus (Zonitidae) (orchid snail) is formally recorded as a naturalised species, although its presence since the 1950s has been recognised in the popular press and unpublished plant protection records. Helicodiscus singleyanus (Helicodiscidae) (Singley's subterranean discus snail) is recorded in the naturalised fauna for the first time with recognition of the presumedly indigenous species Hydrophrea academia as a new junior synonym; this small, largely subterranean species has been known from widely scattered localities since 1970. Lehmannia valentiana (Limacidae) (Valencia slug) is recorded in New Zealand for the first time, although specimen material indicates that it has been established at various localities in the North Island since the 1970s. Prietocella barbara (Hygromiidae) (banded conical snail) is formally added to the naturalised fauna, although its establishment was recorded in 1983 but not published; this species is rapidly spreading through northernmost New Zealand. Coneuplecta calculosa (Euconulidae) (calculus cone snail) is the species most recently confirmed (1995) as a naturalisation, and is known at present from a single locality. Family and generic diagnoses are presented; these were initially developed from the literature, but incorporate much new anatomical observation. All species are redescribed and illustrated on the basis of conchological and anatomical observations of New Zealand and extralimital material, with new or corrected anatomical data, and haploid chromosome numbers taken from the literature. The systematic status of each species is discussed, and information is presented on their distribution, history in New Zealand, and biology. A key to their identification is included. Methods for collection, preparation, and curation of these molluscs are briefly outlined. The systematic treatment of the taxa and the key are supported by a comprehensive description and discussion of the body plan and organ systems in Stylommatophora that are important in systematics and in taxon recognition. Most species are illustrated from life in a series of colour plates. Checklist of Taxa Family AGRIOLIMACIDAE Genus Deroceras Rafinesque Schmaltz, 1820 Subgenus Deroceras Rafinesque Schmaltz, 1820 laeve (Mūller, 1774) - marsh slug panormitanum (Lessona & Pollonera, 1882) - brown field slug Subgenus Agriolimax Mōrch, 1865 reticulatum (Mūller, 1774) - grey field slug Family ARIONIDAE Subfamily Arioninae Genus Arion d'Audebard de Ferussac, 1819 distinctus Mabille, 1868 - Mabille's orange soled slug hortensis d'Audebard de Ferussac, 1819 - Ferussac's orange soled slug intermedius Normand, 1852 - glade slug Family COCHLICOPIDAE Genus Cochlicopa d'Audebard de Ferussac, 1821 l ubrica (Mūller, 1774) - slippery moss snail Family EUCONULIDAE Genus Coneuplecta Mōllendorff, 1893 calculosa (Gould, 1852) - calculus cone snail Family FERUSSACIIDAE Genus Cecilioides d'Audebard de Ferussac, 1814 Subgenus Cecilioides d'Audebard de Ferussac, 1814 acicula (Mūller, 1774) - blind pin snail Family HELICIDAE Subfamily Helicinae Genus Cantareus Risso, 1826 aspersus (Mūller, 1774) - brown garden snail Family HELICODISCIDAE Genus Helicodiscus Morse, 1864 Subgenus Hebetodiscus Baker, 1929 singleyanus (Pilsbry, 1889) - Singley's subterranean discus snail Family HYGROMIIDAE Genus Candidula Kobelt, 1871 intersecta (Poiret, 1801) - wrinkled snail Genus Prietocella Schileyko & Monkhorst, 1997 barbara (Linnaeus, 1758) - banded conical snail Family LIMACIDAE Genus Lehmannia Heynemann, 1862 nyctelia (Bourguignat, 1861) - Bourguignat's slug valentiana (d'Audebard de Ferussac, 1823) - Valencia slug Genus Limacus Lehmann, 1864 flavus (Linnaeus, 1758) - yellow cellar slug Genus Limax Linnaeus, 1758  Subgenus Limax Linnaeus, 1758 maximus Linnaeus, 1758 - tiger slug Family MILACIDAE Genus Milax Gray, 1855 gagates (Draparnaud, 1801) - jet slug  Genus Tandonia Lessona & Pollonera, 1882 budapestensis (Hazay, 1881) - Budapest slug sowerbyi (d'Audebard de Ferussac, 1823) - Sowerby's slug Family PUPILLIDAE Subfamily Lauriinae Genus Lauria Gray, 1840 cylindracea (da Costa, 1778) - chrysalis snail Family TESTACELLIDAE Genus Testacella Draparnaud, 1801 haliotidea Draparnaud, 1801 - shelled slug Family VALLONIIDAE Genus Vallonia Risso, 1826 excentrica Sterki, 1893 - eccentric grass snail Family VERTIGINIDAE Subfamily Vertigininae Genus Vertigo Mūller, 1774 ovata (Say, 1822) - grassland whorl snail Family ZONITIDAE Subfamily Zonitinae Genus Oxychilus Fitzinger, 1833 Subgenus Oxychilus Fitzinger, 1833 alliarius (Miller, 1822) - garlic glass snail cellarius (Mūller, 1774) - cellar glass snail draparnaudi (Beck, 1837) - Drapamaud's glass snail Genus Vitrea Fitzinger, 1833  Subgenus Vitrea Fitzinger, 1833 crystallina (Mūller, 1774) - crystal snail Subfamily Gastrodontinae Genus Zonitoides Lehmann, 1862 Subgenus Zonitoides Lehmann, 1862 arboreus (Say, 1816) - orchid snail