Group B Key

Group B. Shell taller than wide; reflected lip; lip reflected to thick, one or more tooth, columnar to pupilliform

B1. > 3 mm – some Gastrocopta (in part), Pupillidae

B2. < 3 mm – Carychium, some Gastrocopta (in part), Vertigo

B1. Pupilliform, > 3 mm – some Gastrocopta (in part), Pupillidae

These are larger, among the “taller than wide” pupilliform land snails and are easily distinguished. The two Snaggletooth snails in this group are distinguished from the Snaggletooth snails in B2 by their larger size, nearer to or over 4 mm, and robust form. Approximate size range: 3-4 mm. The key below is modified from sources. Gastrocopta armifera (1st image or left), Gastrocopta similis (2nd image or center), Pupoides albilabris (3rd image or right)

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. Use either or both of the keys below to get to either group.

Simple key to Group B1 snails

​1. If the snail is slimmer, more “turreted”, no apertural teeth, then - Pupillidae (Pupillid snails)

  • ​1a. If more than 3.5 mm tall, very small parietal tooth, dark reddish-brown in color, and more columnar in shape than conical - Go to Pupillidae Page for Pupilla muscorum, the Widespread Column Snail.

  • 1b. ~4 mm tall, more conical than columnar, brown shell with a white apertural margin and no teeth – Go to Pupillidae Page for Pupoides albilabris, the White-lip Dagger Snail.

​2. If the snail is rounder, then - Gastrocopta (Snaggletooth snails)

  • ​2a. If the columellar tooth is more triangular and its lamina (layers) seem fewer (1st image or left) – Go to Group B1 Gastrocopta Page for Gastrocopta armifera, the Armed Snaggletooth Snail.

  • 2b. If the columellar tooth is larger, extends more vertically, and appears more layered, but may seem to bow out in the middle (2nd image or right) - Go to Group B1 Gastrocopta Page for Gastrocopta similis, the Great Lakes Snaggletooth Snail.

B2. < 3 mm – Carychium, some Gastrocopta (in part), Vertigo

The images below are Carychium (left), Gastrocopta (center), Vertigo (right).

Carychium (Thorn snails) have a shell that is more columnar/conical (fusiform) with one small tooth on the parietal wall - see left image below. Approximate size range: < 2 mm. Go to the Carychium (Thorn Snails) Page for information.

​The other snails are the less columnar/conical “taller than wide” pupilliform land snails and are not so easily distinguished. The overall best source for identification is Nekola and Coles (2010).

Key to these two pupillid-like groups modified from Dourson (2015)

1a. multiple teeth; in most cases, the apertural lip more openly reflected (like a horn); right side of aperture smooth - Go to Group B2 Gastrocopta Page for information.

1b. multiple teeth, apertural lip more narrowly reflected, right side of aperture with slight indentation in most cases - Go to Vertigo (“Vertigo snails)” Page for information.

​Key to these two pupillid-like groups modified from Nekola and Coles (2010)

​1a. At least one lamella in aperture – (2)
1b. No apertural lamella, less than 3 mm tall – Vertigo, in part - Go to Vertigo (“Vertigo snails)” Page for information.

​2a. Parietal lamella fused with angular forming a complex bilobed structure – Gastrocopta, in part - Go to Group B2 Gastrocopta Page for information.
2b. Parietal lamella a simple peg or plate (might be absent); angular lamellae (if present) not fused with parietal lamellae – (3)

​3a. Fresh shells white to clear – Gastrocopta, in part, - Go to Group B2 Gastrocopta Page for information.
3b. Fresh shells pale to deep reddish brown, < 3mm tall, shell apex tapered – Vertigo, in part - Go to Vertigo (“Vertigo snails)” Page for information.