Gastrocopta - Snaggletooth Snails from Group B2 smaller species (Family Vertiginidae)
These eight species of Snaggletooth snails given in the databases for Indiana are distinguished from others in its genus by their smaller size, less than 3 mm. The size and nature of the teeth are used to distinguish among these smaller Snaggletooth snails. Six of these species are listed from Indiana in NatureServe and Nekola and Cole (2010) - only Gastrocopta rupicola and G. sterkiana are not. For completeness, all are included here.
The key below, developed using a couple of sources, works in a pinch, but I do absolutely recommend using the complete key for Gastrocopta with good photos from Nekola and Cole (2010). The information at Hotopp et al. (2013) and Oesch et al. (2013) will also be helpful. See "References" for links.
Key to the Group B2 Species of Gastrocopta (explanation of teeth repeated below the key):
1a. Angulo-parietal lamella a simple peg-like tooth – (2)
1b. Angulo-parietal lamellae not peg-shaped – (3)
2a. Shell narrowly conical, with height more than 1½ times width; lower palatal lamella deeply entering aperture - G. pentodon
2b. Shell broadly conical, with height less than 1½ times width; lower palatal lamella not deeply entering aperture - G. tappaniana
3a. Angulo-parietal lamella a single large, folded sheet - G. contracta
3b. Angular and parietal lobes of angulo-parietal lamellae distinct - (4)
4a. Fresh shells whitish to pale horn yellow - (5)
4b. Fresh shells yellow-brown to brown-red - (7)
5a. Lobes of angulo-parietal lamella distinct, more or less parallel – (6)
5b. Angulo-parietal lobes intersecting, in form of a curved X-like structure - G. rupicola
6a. Basal and palatal lamellae absent; shell >2.4 mm tall - G. corticaria
6b. Basal and palatal lamellae present; shell <2.4 mm tall - G. holzingeri
7b. Alive or recently dead clean shells horn-yellow to light yellow-brown, translucent, aperture margin with thickened callus - G. rupicola
7a. Alive or recently dead clean shells deep tan to brown, opaque – (8)
8a. Angular lobe flaring upwards, triangular in shape, distinct from and crossing over the parietal lobe; lower palatal lamella inserted moderately deep, lying at a 45° angle to aperture axis; shell height usually >2.4 mm; thick callus plate present on aperture margin - G. sterkiana
8b. Angular lobe linear and fused to the middle of the parietal lobe; lower palatal lamella inserted deeply, lying parallel to aperture; shell height usually <2.4 mm; no callus - G. procera
Arrangement of teeth:
The pair of teeth on upper aperture are the angular and parietal. They may be in the bilobed form as shown here, or in other configurations.
The tooth on the left, up against the columella (the central shaft of the spiral) is the columellar tooth. It is variously shaped.
The remaining teeth are the basal and the palatal group.
Gastrocopta contracta (Say, 1822)
Bottleneck Snaggletooth
Gastrocopta contracta (Say, 1822)
Description: While a typical smaller snaggletooth, the angulo-parietal tooth is very large, fused as one, and folded - unique and easily seen. The shell is rather more conical. The apertural lip is thin but widely reflected and the aperture tends to triangular in shape. The columellar tooth (lamella) is roundish, large and laminate. The columellar tooth (lamella) is roundish, large and laminate Its height ~2-2.5 mm. (see Nekola and Coles 2010 for all the Gastrocopta)
Habitat: It can be found in a variety of open habitats including roadsides, along railroads, cedar glades as well mesic or xeric woods. It can co-occur with other snaggletooth snails.
Status: widespread in suitable habitat.
Bark Snaggletooth
Gastrocopta corticaria (Say, 1816)
Characters: Shell taller than wide; reflected lip; apertural teeth present if less than ~ 4 mm in height; pupilliform; Size: ~2.5 - 3 mm in height; thin and small reflected lip; aperture has few lamella, generally no more than 3 with the basal and palatal lamella absent; angulo and parietal lamella are small and may appear bilobed in lateral view, or partially fused. (see Nekola and Coles 2010 for all the Gastrocopta)
Habitat: These have been variously recorded as “bluffs with wooded hillsides along mesic valleys” and “wooded wetlands”, as well as “mature upland forests and glades”. They will be found under and in organic debris, crevices of rotting logs, and red cedar litter. May be found crawling on tree trunks.
Status: scattered across the state. Likely could be found in more counties
Gastrocopta holzingeri (Sterki, 1889)
Lambda Snaggletooth
Gastrocopta holzingeri (Sterki, 1889)
Characters: Shell taller than wide; reflected lip; apertural teeth present if less than ~ 4 mm in height; pupilliform; ~1.75 mm in height. Six teeth including a bilobed angulo-parietal tooth, basal and palatal teeth inserted away from lip. (see Nekola and Coles 2010 for all the Gastrocopta)
Habitat: Can be found in a variety of situations from wooded floodplains to upland forests to upland grasslands with permanent moisture (Leonard 1959).
Status: Only found in three counties, two in the southeast. Likely could be found in more counties.
Gastrocopta pentadon (Say, 1822)
Comb Snaggletooth
Gastrocopta pentadon (Say, 1822)
Characters: Shell taller than wide; reflected lip; apertural teeth present if less than ~ 4 mm in height; pupilliform; ~1.5 - 2 mm in height; the angulo-parietal looks stubby and narrow; can have 5-8 teeth.
Comparison: This species is similar to others including G. holzingeri and G. tappaniana, but can be distinguished from the former by the angulo-parietal tooth and from the latter by lower palatal lamella (see Nekola and Coles 2010 for all the Gastrocopta).
Habitat: The Comb Snaggletooth can be found in a variety of habitats, both wooded and grassland in and around litter. Nekola and Coles (2010) note a preference for leaf litter.
Status: scattered distribution across the state. Likely could be found in more counties.
Gastrocopta procera (Gould, 1840) with mm scale
Wing Snaggletooth
Gastrocopta procera (Gould, 1840)
Characters: Shell taller than wide; reflected lip; apertural teeth present if less than ~ 4 mm in height; pupilliform; ~2 - 3 mm in height; angulo-parietal lobes intersect to form a X-shape bi-lobed structure; light brown color; lip thin, lower palatal long, angled away from upper palatal lamella, and deep into shell. (see Nekola and Coles 2010 for all the Gastrocopta)
Habitat: The Wing Snaggletooth can be found in and around the organic debris and stones/rocks of forest litter; also more open habitats such as prairie and glades.
Status: Very parsely distributed in three counties across the state, two in the southeast. Likely could be found in more counties.
no image for G. sterkiana.
Neither of these species are noted for Indiana at NatureServe (2022) or in Nekola and Coles (2010). Questionable identifications? – but, you never know?
Tapered Snaggletooth
Gastrocopta rupicola (Say, 1821)
a Snaggletooth Snail
Gastrocopta sterkiana Pilsbry, 1917
Characters: Shell taller than wide; reflected lip; apertural teeth present if less than ~ 4 mm in height; pupilliform. Gastrocopta rupicola image at https://bit.ly/3aAnoQj. No image for Gastrocopta sterkiana.
Comparison: Gastrocopta rupicola when alive or recently dead has shells with a horn-yellow to light yellow-brown color, translucent, with a thickened callus on the aperture margin. Gastrocopta sterkiana, when alive or recently dead has shells with a deep tan to brown, opaque. In comparison to G. procera, G. sterkiana has a shell height usually < 2.4 mm with and angular lobe flaring upwards and triangular in shape.
Gastrocopta tappaniana (C. B. Adams, 1842) with mm scale
White Snaggletooth
Gastrocopta tappaniana (C. B. Adams, 1842)
Characters: Shell taller than wide; reflected lip; apertural teeth present if less than ~ 4 mm in height; pupilliform; ~1.5 - 2.5 mm in height. Angulo-parietal tooth fused; outer lip thin and slightly reflected; 6-9 apertural teeth; shell shape is ovate.
Comparison: This species may be confused with G. pentadon, but its shell is larger and more conical. As well, its lower palatal lamella does not enter the aperture as deeply as that of G. pentadon.
Habitat: The White Snaggletooth can be collected in and around leafy or woody detritus in moister areas of bottomland forests (floodplain, wooded wetlands, or prairies)
Status: scattered across the state. Likely could be found in more counties.
