Limacoidei

Copper button snail Mesomphix cupreus, copyright Levi Sam Juno.

Belongs within: Heterobranchia.
Contains: Pristilomatidae, Oxychilidae, Gastrodontidae, Chronidae, Trochomorphidae, Euconulinae, Liardetiini, Parmacelloidea, Vitrinidae, Agriolimacidae, Limacinae, Zonites, Ventridens, Paravitrea, Glyphyalinia, Helicarionoidea.

The Limacoidei, sometimes referred to as the ‘limacoid clade’ or Limacoidea sensu lato, are terrestrial gastropods characterised by a radula bearing elongate marginal teeth without entocones. This modification of the radula may represent an adaptation to an omnivorous diet.

Members of the clade include the Limacoidea, slugs and semislugs found in more humid biotopes. These are characterised by reduction of the spermatophore and epiphallus. Limacidae are medium to large slugs with a large mantle shield and a mostly circular cross-section; if a dorsal keel is present, it is restricted to the posterior end of the body (Stanisic et al. 2010).

The Gastrodontoidea are mostly small snails, characterised by reductions in the stimulators and lung venation. The Trochomorphoidea have a more generalised generalised form of the stimulator than other Limacoidei, inserting on the penis rather than on the atrium. The Zonitidae have the capsular gland at least partially around the vagina whereas other limacoids have it only around the oviduct.

Wild slug chases
Published 3 August 2009
Daudebardia rufa (Oxychilidae)—note the small shell compared to the body. This species belongs to a subfamily, Daudebardiinae, that also happens to be carnivorous. Photo by Jiří Novák.

Before I get on to the subject of today’s post—a bit of a gripe. I have a feeling that I’m not going to say anything of note or value here, so feel free to skip forward a couple of paragraphs while I ramble.

It should come as no surprise to anyone that, contrary to common assumption, not all public information is available on the internet—a lot of it is still locked up in those paper things that we call “books” (or printed journals, or what-have-you). This is becoming a serious issue in a time when, for so many people, a search for information begins and ends with Google and anything that a search engine doesn’t find is treated as if it doesn’t exist. That particular problem, however, is a topic for another day. The point that I specifically wanted to raise is that some topics remain unusually under-represented online. Malacology is one of those mysterious absences. Or, to be more accurate, framework-level malacology is*. Run an online search for, say, Mitridae or Fossarinae or Stomatella, and you’ll get a ton of pretty pictures of their shells, but it’s surprisingly difficult to find out what they actually are. What features, specifically, maketh a mitrid? What defines a Diodora? I’ve done a few posts on gastropod families or superfamilies by now, and to be honest I’ve usually ended up blabbing on madly about any old guff in a desperate attempt to hide the point that all I really know about the taxon in question is its name (not being a malacologist myself, I have very little idea where to start looking to find out**). So why is there this particular pot-hole in the information superhighway? These are not obscure, unfamiliar animals. They are large, often cosmopolitan taxa, familiar to many a beach-goer or amateur shell collector.

*If anyone knows of any useful sites, I’d be happy to know about them.

**So why do I write about these things if I don’t know anything about them? Because, to be honest, I’m writing these posts for my own benefit and to teach something to myself, not to you. I may not have known anything whatsoever about clausilioids before I started writing a post on them, but hopefully I knew just a little bit more when I’d finished. And if any of you benefited from my learning curve, then that’s just the gravy.

Mesomphix andrewsae (Gastrodontidae). Photo by slapcin.

Anyway, enough of that, on to the actual topic of this post (and if you did slog through the last couple of paragraphs, a quick reminder that I have absolutely no idea about anything in there, and was almost certainly talking completely out of my khyber). Gastrodontoidea are an assemblage of land snails recognised by Hausdorf (1998) as including six families—Pristilomatidae, Chronidae, Euconulidae, Trochomorphidae, Gastrodontidae and Oxychilidae (the names of two families have been corrected to the names used by Bouchet & Rocroi 2005). Previously these families had been included in the Limacoidea, which Hausdorf divided up into a number of superfamilies. However, he did not dispute the monophyly of the original extended Limacoidea, and many authors continue to use the larger grouping rather than recognising Hausdorf’s subdivisions.

Geotrochus obscura (Trochomorphidae). It does not take much to realise how these creatures got their name, does it? Photo from here.

Hausdorf’s analysis is not without its problems. For a start, he was coding families rather than individual species, which (a) assumes that the families you’re using are monophyletic, and (b) usually requires the author to estimate the ‘ground-state’ coding for a family, which can be a hazardous exercise (just because the majority of members of a family possess a particular character state does not necessarily mean that state is ancestral for that family). Secondly, the characters that supported monophyly of Gastrodontoidea were reductions of the stimulator in the male genitalia (among other things, the stimulator is the part of the genitalia that produces the love darts in those snails that have them ) and of the venation of the lung. Not only are reductions or losses always somewhat suspicious as supporting characters—if it is easier to lose a character than to gain it, they will probably be prone to homoplasy—but each one of these characters was both homoplastic with other non-gastrodontoid limacoids, and had been reversed in some supposed gastrodontoids. Hausdorf’s Gastrodontoidea was not monophyletic in the molecular analysis of Wade et al. (2006) (but pretty much no relationships within the extended Limacoidea were well-supported in that analysis), nor did it appear in the morphological tree of Barker (2001) (which, however, did not include support levels for any of its results).

Most ‘gastrodontoids’ seem to be rather small (often only a few millimetres in diameter). Many limacoids have small shells compared to their bodies, and are unable to fully retract into them (Bouchet & Abdou 2001). The Microcystinae, a subfamily of the Euconulidae (though Hyman et al., 2007, suggested they may be closer to the Trochomorphidae), are ovoviviparous—that is, they incubate their eggs internally until they hatch out and are released as live young*.

*Is there a better way of putting this? I just realised that the phrase “live young” is a bit unfortunate—after all, it’s not as if eggs are dead.

Euconulus fulvus (Euconulidae), from here.

Gastrodontidae and Oxychilidae possess a cartilaginous love-dart, but other families are dart-less. Gastrodontidae also possess an internal duct between the male and female parts of the reproductive system (remember, all pulmonates are hermaphrodites), and are apparently able to fertilise themselves. Indeed, Barker (2001) lists gastrodontids among families of snail for which some individuals lack the male penis, so they are only able to fertilise themselves or be fertilised by others, not fertilise others. I find this intriguing, as explanations for the ways and means of hermaphroditism often seem to proceed on the assumption that, because of the different required reproductive commitments, ’tis preferable to fertilise than be fertilised (love-darts, for instance, are thought to have evolved to prevent one partner from fertilising the other, then taking off before it is able to be fertilised itself). Penislessness in gastrodontids would seem to go against that assumption, so why would it develop? Is it that, what receptive-only individuals lose in the ability to produce more offspring, they gain in having more control themselves over how those offspring are provided for?

Systematics of Limacoidei
<==Limacoidei [Limacacea, Limaxina, Zonitinia]BR17
    |--GastrodontoideaBR17
    |    |--PristilomatidaeBR17
    |    |--OxychilidaeBR17
    |    `--GastrodontidaeSS10
    |--TrochomorphoideaBR17
    |    |--ChronidaeBR17
    |    |--TrochomorphidaeSS10
    |    |--Staffordia Godwin-Austen 1907 [Staffordiidae, Staffordiinae, Staffordioidea]BR05
    |    |    `--*S. daflaensis (Godwin-Austen 1883) [=Macrochlamys daflaensis]BR17
    |    |--Dyakiidae [Dyakioidea]BR17
    |    |    |--Dyakia Godwin-Austen 1891 [Dyakiinae, Dyakiini, Dyakinae]BR05
    |    |    |    `--*D. hugonis (Pfeiffer 1863) [=Helix hugonis]BR17
    |    |    |--Sasakina Rensch 1930 [=Sasakia Rensch 1930 non Moore 1896; Sasakinae, Sasakininae]BR05
    |    |    |    `--*S. oxyconus (Martens 1896) [=Trochonanina oxyconus, *Sasakia oxyconus]BR17
    |    |    `--Pseudoplecta Laidlaw 1932 [Pseudoplectinae]BR05
    |    |         `--*P. bijuga (Stoliczka 1873) [=Rotula bijuga]BR17
    |    `--EuconulidaeBR17
    |         |  i. s.: AfroguppyaFGN07
    |         |         Conibycus Thiele 1928S88
    |         |         Microcystina calcarata Hedley 1891S88
    |         |         Dryachloa Thompson & Lee 1980BP90
    |         |           `--D. daucaBP90
    |         |         Guppya Mörch 1867BP90
    |         |           |--G. gundlachiBP90
    |         |           |--G. sterkiiH68
    |         |           `--G. vacansG79
    |         |         Turrisitala Iredale 1933SS10
    |         |           `--*T. normalis Iredale 1933 [incl. Helix turriculata Cox 1868, T. wildiana Iredale 1937]SS10
    |         |         Queridomus Iredale 1937SS10
    |         |           `--*Q. grenvillei (Brazier 1876) [=Helix (Conulus) grenvillei]SS10
    |         |--EuconulinaeBR17
    |         `--Microcystinae [Microcysti, Microcystidae]BR17
    |              |  i. s.: Innesoconcha Iredale 1944SS10
    |              |           |--*I. catletti (Brazier 1872) (see below for synonymy)SS10
    |              |           `--I. princeps Iredale 1944SS10
    |              |         Melloconcha Iredale 1944 [incl. Tribocystis Iredale 1944]SS10
    |              |           |--*M. delecta Iredale 1944SS10
    |              |           |--M. flavescens (Iredale 1944)SS10
    |              |           `--M. rosacea (Iredale 1944) [incl. Tribocystis alma Iredale 1944]SS10
    |              |         Allenoconcha Preston 1913SS10
    |              |           `--*A. basispiralis Preston 1913 (see below for synonymy)SS10
    |              |         Fanulena Iredale 1945 (see below for synonymy)SS10
    |              |           `--*F. insculpta (Pfeiffer 1846) (see below for synonymy)SS10
    |              |         Greenwoodoconcha Preston 1913SS10
    |              |           `--*G. nux (Sykes 1900) (see below for synonymy)SS10
    |              |         Mathewsoconcha Preston 1913 [incl. Belloconcha Preston 1913]SS10
    |              |           `--M. suteri (Sykes 1900) (see below for synonymy)SS10
    |              |         Quintalia Preston 1913SS10
    |              |           `--*Q. stoddartii (Gray 1834) [=Carocolla stoddartii]SS10
    |              |         Roybellia Preston 1913SS10
    |              |           `--*R. platysoma (Sykes 1900) [=Trochononanina platystoma; incl. R. depressa Preston 1913]SS10
    |              |--LiardetiiniBR05
    |              |--Microcystis Beck 1837 non Kutzing 1833 (ICBN) [Microcystini]BR05
    |              |    `--*M. pellicula (Férussac 1821) [=Helicolimax pellicula]BR17
    |              `--Philonesia Sykes 1900 [Philonesiae, Philonesiini]BR05
    |                   `--*P. baldwini (Ancey 1889) [=Microcystis baldwini]BR17
    `--+--ParmacelloideaH00
       `--+--Limacoidea [Aceratophora, Limaxinia]H00
          |    |  i. s.: Grandipatula Cossmann 1889 [Grandipatulidae, Grandipatulinae]BR05
          |    |           |--*G. (Grandipatula) hemisphaerica (Michaud 1837) [=Helix hemisphaerica]BR17
          |    |           `--G. (Sphaerozonites) oppenheimi (Pfeffer 1929)TTE93
          |    |         Palaeoxestina Wenz 1919 [Palaeoxestinidae, Palaeoxestininae]BR05
          |    |           `--*P. occlusa (Edwards 1852) [=Helix occlusa]BR17
          |    |         RhysotaBR17
          |    |--VitrinidaeH00
          |    `--+--Boettgerilla Simroth 1910BR05 [BoettgerillidaeH00]
          |       |    `--*B. compressa Simroth 1910BR17
          |       `--+--AgriolimacidaeH00
          |          `--Limacidae [Limacidia, Limacina, Limaxia]H00
          |               |  i. s.: Malacolimax tenellus (Müller 1774)HM07
          |               |         Lehmannia Heynemann 1862SS10
          |               |           |--*L. marginata (Müller 1774) [=Limax marginata]SS10
          |               |           |--L. nyctelia (Bourguignat 1861) [=Limax nyctelius; incl. Li. legrandi Tate 1881]RAS75
          |               |           |--L. poirieriR66
          |               |           `--L. valentiana (Férussac 1823)SS10
          |               |         Limacus Lehmann 1864SS10
          |               |           `--L. flavus (Linnaeus 1758)SS10 (see below for synonymy)
          |               |--LimacinaeBR05
          |               `--Eumilax Boettger 1881 [Eumilacinae]BR05
          |                    `--*E. brandti (Martens 1880) [=Limax brandti]BR17
          `--+--Zonitidae [Ceratophora, Zonitacea, Zonitoidea]H00
             |    |--ThomeonaninaPB27
             |    |--KerkophorusPB27
             |    |--MicrokerkusPB27
             |    |--Suterella Iredale 1915P61
             |    |    `--*S. novarae (Pfeiffer 1862) [=Helix novarae]P61
             |    |--Vitrinizonites Binney 1879BP90
             |    |    `--V. latissimusBP90
             |    |--Pilsbryna Baker 1926BP90
             |    |    |--P. aureaBP90
             |    |    `--P. castaneaBP90
             |    |--ZonitesBR05
             |    |--Nesovitrea Cooke 1921BP90
             |    |    |--N. binneyanaBP90
             |    |    |--N. electrinaBP90
             |    |    `--N. hammonisV09
             |    |--Mesomphix Rafinesque 1819BP90
             |    |    |--M. capnodes (see below for synonymy)H65
             |    |    |--M. cupreusBP90
             |    |    |    |--M. c. cupreusBP90
             |    |    |    `--M. c. politusBP90
             |    |    |--M. friabilisH68
             |    |    |--M. inornatusH68
             |    |    |--M. pilsbryiR65
             |    |    |--M. ruidusH68
             |    |    `--M. vulgatusH68
             |    |--RetinellaBP90
             |    |    |--R. burringtoniG59
             |    |    |--R. dallianaR64
             |    |    |--R. electrinaD63
             |    |    |--R. indentataG59
             |    |    |--R. nitensJ63
             |    |    `--R. rhoadsiG59
             |    |--VentridensTMT96
             |    |--ParavitreaBP90
             |    |--Striatura Morse 1864BP90
             |    |    |--S. exiguaBP90
             |    |    |--S. ferreaBP90
             |    |    |--S. meridionalisB63
             |    |    `--S. milliumPF15
             |    |         |--S. m. milliumPF15
             |    |         `--S. m. meridionalisPF15
             |    `--GlyphyaliniaBP90
             `--HelicarionoideaH00

*Allenoconcha basispiralis Preston 1913 [incl. A. belli Preston 1913, A. congener Preston 1913, A. mathewsi Preston 1913, A. monspittensis Preston 1913, A. perdepressa Preston 1913, A. royana Preston 1913]SS10

Fanulena Iredale 1945 [incl. Dolapex Iredale 1945, Lutilodix Iredale 1945, Parcolena Iredale 1945]SS10

*Fanulena insculpta (Pfeiffer 1846) [=Helix insculpta; incl. H. basiodon Morelet 1866, Fanulena nepeanensis Iredale 1945]SS10

*Greenwoodoconcha nux (Sykes 1900) [=Microcystis nux; incl. M. castaneocincta Sykes 1900, Greenwoodoconcha castaneocincta serica Iredale 1945, G. tomi Preston 1913]SS10

*Innesoconcha catletti (Brazier 1872) [=Helix (Microcystis) catletti; incl. Microcystis catletti major Hedley 1891, Innesoconcha catletti subconica Iredale 1944]SS10

Limacus flavus (Linnaeus 1758)SS10 [=Limax flavusSS10, Lehmannia (Limacus) flavaRAS75; incl. Limax bicolor Selenka 1865SS10, *Limacus breckworthianus Lehmann 1864SS10, Limacella concavaG40, Limax megalodontes Quoy & Gaimard 1824SS10, Limax olivaceus Gould 1852SS10]

Mathewsoconcha suteri (Sykes 1900) [incl. M. albocincta Preston 1913, *M. belli Preston 1913, Belloconcha compacta Preston 1913, B. norfolkensis Preston 1913]SS10

Mesomphix capnodes [incl. M. cupreus miktus Pilsbry 1946, M. cupreus ozarkensis (Pilsbry & Ferriss 1946]H65

*Type species of generic name indicated

References

Barker, G. M. 2001. The Biology of Terrestrial Molluscs. CABI.

Bouchet, P., & A. Abdou. 2001. Recent extinct land snails (Euconulidae) from the Gambier Islands with remarkable apertural barriers. Pacific Science 55 (2): 121–127.

[BR05] Bouchet, P., & J.-P. Rocroi. 2005. Classification and nomenclator of gastropod families. Malacologia 47 (1–2): 1–397.

[BR17] Bouchet, P., J.-P. Rocroi, B. Hausdorf, A. Kaim, Y. Kano, A. Nützel, P. Parkhaev, M. Schrödl & E. E. Strong. 2017. Revised classification, nomenclator and typification of gastropod and monoplacophoran families. Malacologia 61 (1–2): 1–526.

[B63] Branson, B. A. 1963. Notes on snail distribution and leech feeding habits in Oklahoma. Nautilus 76 (4): 148–149.

[BP90] Burch, J. B., & T. A. Pearce. 1990. Terrestrial Gastropoda. In: Dindal, D. L. (ed.) Soil Biology Guide pp. 201–309. John Wiley & Sones: New York.

[D63] Dimelow, E. J. 1963. Mollusks from hardwoods of the Chigneto Isthmus. Nautilus 77 (1): 21–23.

[FGN07] Fontaine, B., O. Gargominy & E. Neubert. 2007. Land snail diversity of the savanna/forest mosaic in Lopé National Park, Gabon. Malacologia 49 (2): 313–338.

[G79] Gibbons, J. S. 1879. Notes on the habits and distribution, &c., of certain W. Indian Pulmonifera. Journal of Conchology 2: 129–134.

[G40] Gray, J. E. 1840. A Manual of the Land and Fresh-water Shells of the British Islands, with figures of each of the kinds. By William Turton, M.D. A new edition, thoroughly revised and much enlarged. Longman, Orme, Brown, Green, and Longmans: London.

[G59] Grimm, W. 1959. Land snails of Carroll County, Maryland. Nautilus 72 (4): 122–127.

Hausdorf, B. 1998. Phylogeny of the Limacoidea sensu lato (Gastropoda: Stylommatophora). Journal of Molluscan Studies 64 (1): 35–66.

[H00] Hausdorf, B. 2000. Biogeography of the Limacoidea sensu lato (Gastropoda: Stylommatophora): vicariance events and long-distance dispersal. Journal of Biogeography 27: 379–390.

[HM07] Honek, A., & Z. Martinkova. 2007. A field method for quantifying the grazing activity of slugs, with particular reference to Arion lusitanicus (Mollusca). Malacologia 49 (2): 273–281.

[H65] Hubricht, L. 1965. Notes on Zonitidae. Nautilus 78 (4): 133–135.

[H68] Hubricht, L. 1968. The land snails of Mammoth Cave National Park, Kentucky. Nautilus 82 (1): 24–28.

Hyman, I. T., S. Y. W. Ho & L. S. Jermiin. 2007. Molecular phylogeny of Australian Helicarionidae, Euconulidae and related groups (Gastropoda: Pulmonata: Stylommatophora) based on mitochondrial DNA. Molecular Phylogenetics and Evolution 45; 792–812.

[J63] Jánossy, D. 1963. Letztinterglaziale Vertebraten-Fauna aus der Kálmán Lambrecht-Höhle (Bükk-Gebirge, nordost-Ungarn) I. Acta Zoologica Academiae Scientiarum Hungaricae 9 (3–4): 293–331.

[PB27] Pilsbry, H. A., & J. Bequaert. 1927. The aquatic mollusks of the Belgian Congo, with a geographical and ecological account of Congo malacology. Bulletin of the American Museum of Natural History 53 (2): 69–602, pls 10–77.

[PF15] Pilsbry, H. A., & J. H. Ferriss. 1915. Mollusca of the southwestern states, VII: the Dragoon, Mule, Santa Rita, Baboquivari, and Tucson Ranges, Arizona. Proceedings of the Academy of Natural Sciences of Philadelphia 67 (2): 363–418, pls 8–15.

[P61] Powell, A. W. B. 1961. Shells of New Zealand: An illustrated handbook 4th ed. Whitcombe and Tombs Limited: Christchurch.

[RAS75] Regteren Altena, C. O. van, & B. J. Smith. 1975. Notes on introduced slugs of the families Limacidae and Milacidae in Australia, with two new records. J. Malac. Soc. Aust. 3 (2): 63–80.

[R64] Ross, L. T. 1964. The land mollusks of Siesta Key, Sarasota County, Florida. Nautilus 78 (2): 50–52.

[R65] Ross, L. T. 1965. Two new land mollusk records from Florida. Nautilus 79 (2): 70–71.

[R66] Ross, L. T. 1966. Lehmannia in Massachusetts. Nautilus 80 (2): 71–72.

[S88] Solem, A. 1988. Non-camaenid land snails of the Kimberley and Northern Territory, Australia. I. Systematics, affinities and ranges. Invertebrate Taxonomy 4: 455–604.

[SS10] Stanisic, J., M. Shea, D. Potter & O. Griffiths. 2010. Australian Land Snails vol. 1. A. field guide to eastern Australian species. Bioculture Press: Mauritius.

[TMT96] Tillier, S., M. Masselot & A. Tillier. 1996. Phylogenetic relationships of the pulmonate gastropods from rRNA sequences, and tempo and age of the stylommatophoran radiation. In: Taylor, J. D. (ed.) Origin and Evolutionary Radiation of the Mollusca pp. 267–284. Oxford University Press: Oxford.

[TTE93] Tracey, S., J. A. Todd & D. H. Erwin. 1993. Mollusca: Gastropoda. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 131–167. Chapman & Hall: London.

[V09] Verdcourt, B. (ed.) 2009. Additions to the wild fauna and flora of the Royal Botanic Gardens, Kew. XXVI. Miscellaneous records. Kew Bulletin 64 (1): 183–194.

Wade, C. M., P. B. Mordan & F. Naggs. 2006. Evolutionary relationships among the pulmonate land snails and slugs (Pulmonata, Stylommatophora). Biological Journal of the Linnean Society 87 (4): 593–610.

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