Gastrodontidae

Family Gastrodontidae Tryon, 1866

Species in Canada
Aegopinella nitidula (Draparnaud, 1805) ◆
Glyphyalinia (Glyphyalinia) indentata (Say, 1823)
Glyphyalinia (Glyphyalops) rhoadsi (Pilsbry, 1899)
Mesomphix (Omphalina) cupreus (Rafinesque, 1831)
Mesomphix (Omphix) inornatus (Say, 1822)
Perpolita binneyana (Morse, 1864)
Perpolita electrina (Gould, 1841)
Striatura (Pseudohyalina) exigua (Stimpson, 1850)
Striatura (Pseudohyalina) pugetensis (Dall, 1895)
Striatura (Striatura) milium (Morse, 1859)
Striatura (Striaturops) ferrea Morse, 1864
Ventridens (Ventricallus) intertextus (A. Binney, 1841)
Ventridens (Ventricallus) ligera (Say, 1821)
Ventridens (Ventridens) suppressus (Say, 1829)
Zonitoides (Zonitoides) arboreus (Say, 1817)
Zonitoides (Zonitoides) nitidus (O. F. Müller, 1774)

Genus Aegopinella Lindholm, 1927

  • Polita Clessin 1882: 158; type species by original designation: Helix pura Alder, 1830; non Polita Held, 1837.
  • Aegopinella Lindholm 1927: 324; type species by original designation: Helix pura Alder, 1830.

There are nine species in the western Palaearctic and one species introduced to Canada. Until recently, this group was thought to belong to the family Oxychilidae, or before that, Zonitidae. Until Forcart (1957, 1959), species of this group were considered Retinella (e.g., Pilsbry 1946: 248).

Etymology. Aegopis (a genus of snail)+ Latin diminutive suffix -ella; feminine.

Genus Glyphyalinia E. von Martens, 1892

  • Glyphyalinia E. von Martens 1892 (1890–1901): 117; type species by subsequent designation (H. B. Baker 1928): Helix indentata Say, 1822.

Previously, this genus was included in the family Oxychilidae. In older literature, species of Glyphyalinia were placed in Retinella P. Fischer, 1877, a central and western European group of snails with superficially appearing shells.

Pilsbry (1946) placed group in the genus Retinella, following Baker (1930). The current classification follows Riedel (1980). and Schileyko (2003).

Etymology. Greek: glyph, carved, + Latin: hyalinus, glass. Feminine.

Subgenus Glyphyalinia E. von Martens, 1892

Subgenus Glyphyalops H. B. Baker, 1928

  • Glyphalops H. B. Baker 1928: 15, 19; type species by original designation: Vi­trea rhoadsi Pilsbry, 1899.

Etymology. Derived from Glyphyalina + Greek suffix -ops, having the appearance of.

Genus Mesomphix Rafinesque, 1819

  • Mesompix Rafinesque 1819: 425. Type species by subsequent designation (Herrmannsen 1847 in 1846–1852): Helix laevigata “Rafinesque” A. Férussac, 1832, non Linnaeus, 1767 (= Mesomphix vulgatus H. B. Baker, 1933).

Temperate eastern North America south to Central America; 14 species live in North America alone and two species in Canada.

Etymology. Greek, mesos, middle, + omphalos, umbilicus. Masculine.

Key to Species of Mesomphix in Canada

  • a Umbilicus very small, <1/12 of shell width. Upper surface of whorls smooth, glossy — M. inornatus
  • b Umbilicus larger, 1/5–1/6 of shell width. Upper surface of whorls with pebbly microsculpture, matte — M. cupreus

Subgenus Omphix Pilsbry, 1911

  • Omphix Pilsbry 1911: 479; type species: Mesomphix inornatus (Say, 1822).

An alternative classification treats Omphix as a full genus and further divides it into two subgenera (Schileyko 2003).

Etymology. Derived from Greek: omphalos, umbilicus.

Subgenus Omphalina Rafinesque, 1831

  • Omphalina Rafinesque 1831: 3; type species by monotypy: Om­phalina cuprea Rafinesque, 1831.

Etymology. Greek, omphalos, umbilicus, + Latin suffix -ina, likeness.

Genus Perpolita H. B. Baker, 1928

  • Perpolita H. B. Baker 1928: 15; type species by original designation: Helix hammonis of Baker (1928) = Helix electrina Gould, 1841.

This taxon is often treated as a subgenus of Nesovitrea C. M. Cooke, 1921, a group of similar appearing snails, but with some differing anatomical characters, from the Hawaiian Islands. Pilsbry (1946) followed the classification by Baker (1930), who placed these species in the genus Retinella, subgenus Perpolita.

Key to species of Perpolita in Canada

  • a  Shell dark yellowish to brown. Maximum shell width >4.5 mm —  N. electrina
  • b  Shell colourless or pale yellowish to pale greenish yellow. Maximum shell width <4 mm — N. binneyana

Genus Striatura Morse, 1864

  • Striatura Morse 1864: 17; type species by subsequent designation (H. B. Baker 1928: 33): Helix milium Morse, 1859.

There are nine species in North and Central America (south to Nicaragua), Hawaii, Japan, and Maritime Russia. Four species occur in Canada.

Etymology. Latin: stria, furrow. Feminine.

Subgenus Striatura Morse, 1864

Subgenus Pseudohyalina Morse, 1864

  • Pseudohyalinia Morse 1864: 15; type species by subsequent designation (Kobelt 1879 [1876–1881]: 223): Helix exigua Stimpson, 1850.
  • Pycnogyra Strebel & Pfeffer 1880: 20; type species by monotypy: Helix berendti L. Pfeiffer, 1861.

There are species in North and Central America, Hawaii (Baker 1941, Pilsbry 1948), and the eastern Palaearctic Striatura aperta (Pilsbry & Hirase, 1904) (Prozorova et al. 2006) and S. chishimana (Pilsbry & Hirase, 1904). Schileyko (2003) diverged from other authors in treating this taxon as a full genus. Pycnogyra is included as a synonym on the authority of Hausdorf (1998).

Etymology. Greek pseudes, false, + Hyalina, a former genus of land snails (Greek, hyalinos,glassy or transparent).

Subgenus Striaturops H. B. Baker, 1928

  • Striaturops H. B. Baker 1928: 33; type species by original designation: Striatura ferrea Morse, 1864.

Monotypic. Schileyko (2003) diverged from other authors in treating this taxon as a full genus.

Etymology. Striatura + Greek, ops, having the appearance of.

Key to species of Striatura in Canada

  • 1a Maximum shell width ≥ 2.5 mm (ca 3½ whorls). Sculpture without riblets, but microsculpture exceedingly fine so that the shell has a dull, waxy finish. Umbilicus smaller; maximum shell width ≈5.5× width of umbilicus — S. ferrea
  • 1b Maximum shell width ≤2.5 mm (ca 3½ whorls). Sculpture with closely to widely spaced riblets as well as finer spiral striae. Umbilicus larger; maximum shell width ≥2.5× width of umbilicus — 2
  • 2a Riblets high, cuticular, moderately to widely spaced (9–10 per mm), 30–40 riblets on the last whorl — 3
  • 2b Riblets low, closely spaced, many more riblets than above — S. milium
  • 3a Spiral threads on protoconch strong. British Columbia only — S. pugetensis
  • 3b Spiral threads on protoconch absent or weak. Eastern Canada —S. exigua

Genus Ventridens W.G. Binney & Bland, 1869

  • Ventridens W. G. Binney & Bland 1869: 292; type species by subsequent designation (Nevill 1878): Helix suppressa Say, 1829.

Temperate eastern North America with 21 species; three species in Canada. An alternative classification (e.g., Riedel 1980, Schileyko 2003) regards Ventridens, and its subgenus Ventricallus, as subgenera of Zonitoides.

Etymology. Latin: ventralis, ventral, + dens, tooth; masculine.

Subgenus Ventridens W. G. Binney & Bland, 1869

Subgenus Ventricallus Pilsbry, 1946

  • Ventricallus Pilsbry 1946: 458; type species by original designation: Helix ligera Say, 1821.

Often larger than Ventridens sensu stricto; aperture toothless or with an outer-basal lamina but without a columellar tooth or lamella at any stage of growth. There are nine species in eastern North America. An alternative classification places this taxon as a subgenus in Zonitoides (e.g., Riedel 1980, Schileyko 2003).

Etymology. Latin: ventriculo, the belly, underside, + callus, a callus.

Key to species of Ventridens in Canada

  • 1a Shell height/width = 0.6–0.7, spire quite flattened. Umbilicus ca 1/9 of shell width. Apertural with 1 or 2 denticles persisting in adults — V. suppressus
  • 1b Shell height/width = 0.7–0.8, spire generally rather raised; shell taller, conical-globose. Umbilicus tiny, ca 1/12 of shell width, to almost closed. No apertural denticles in adults — 2
  • 2a Apical surface of whorls with rather sharp colabral and spiral striae. Spiral striae more distinct, on apical and basal surfaces. Base dull—V. intertextus
  • 2b Apical surface of whorls with rather sharp colabral striae only. Spiral striae indistinct and on the base only. Base glossy — V. ligera

Genus Zonitoides Lehmann, 1862

  • Zonitoides Lehmann 1862: 111; type species by monotypy (ICZN 1955, Opinion 335): Helix nitida O. F. Müller, 1774.
  • Zonitellus Baker 1928: 37; type species by original designation: Helix arboreus Say, 1817.
  • Alienator Iredale 1937: 6. Type species by original designation: Helix lyndhurtensis Cox, 1868 = Helix arboreus Say, 1817.

Subgenus Zonitoides Lehmann, 1862

Key to species of Zonitoides in Canada

  • a Body nearly black; with a dull orangish spot, visible through the shell, behind the outer lip when animal retracted. Shell with microscopic spiral striae lacking — Z. nitidus
  • b Body paler-coloured, greyish, lighter on the sides of the foot, head and tentacles darker; without the orange spot, as above. Shell with exceedingly faint microscopic spiral striae present but scarcely visible even under >50× magnification — Z. arboreus