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Group F. Wider than tall; reflected lip, imperforate
This is a messy group of Polygyrid snails of slightly modified forms. Some species will end up being obvious, others not so much.
F1. Heliciform, reflected lip, imperforate, globose to subglobose, toothed - Mesodon (in part), Neohelix (in part)
F2. Heliciform, reflected lip, imperforate, globose to subglobose, toothless - Mesodon (in part), Neohelix, Patera (in part), Webbhelix multilineata
F3. Heliciform, reflected lip, imperforate, subglobose to depressed, toothed - Patera (in part), Xolotrema
F1. Heliciform, reflected lip, imperforate, globose to subglobose, toothed - Mesodon (in part), Neohelix (in part)
These are all large robust Mesodons - all with a significant parietal tooth but with variation in the height of the spire.
Mesodon elevatus (Proud Globe Snail) – imperforate; higher spire and more globose; whorls more tightly coiled than other Mesodons; aperture may be flat or slightly concave at the basal lip; pronounced parietal tooth; 20-26 mm.
Go to Group F Mesodon snails.
Mesodon zaletus (Toothed Globe) – imperforate; largest of those with a single parietal tooth (on the body whorl); superficially similar to M. elevatus but whorls not so tight and not to round; 24-27 mm.
Go to Group F Mesodon snails.
see image of Neohelix dentifera
Neohelix dentifera (Big-tooth Whitelip Snail) – imperforate, subglobose to slightly depressed; single parietal tooth, widely reflected lip, 20-28 mm.
Go to Neohelix snails Page.
F2. Heliciform, reflected lip, imperforate, globose to subglobose, toothless - Mesodon (in part), Neohelix (in part), Patera (in part), Webbhelix multilineata
Neohelix albolabris (Eastern Whitelip Snail) – very large subglobose shell.
Go to Neohelix snails Page.
Neohelix alleni (Western Whitelip Snail) - subglobose shell, parietal callus thin.
Go to Neohelix snails Page.
see image of Mesodon mitchellianus
Mesodon mitchellianus (Sealed Globelet Snail) – not so tightly coiled, normally reflected, small, rounded shell, thin round.
Go to Group F Mesodon snails.
see image of Mesodon normalis
Mesodon normalis (Grand Globe Snail) – heliciform, lip reflected, shell with 5.5-6 whorls, imperforate, no teeth, 21-34 mm diameter
Go to Group F Mesodon snails.
see image of Patera pennsylvanica
Patera pennsylvanica (Proud Globelet Snail) – more tightly coiled, slightly reflected, top edge of aperture points abruptly downward.
Go to Patera Snails Page.
see image of Webbhelix multilineata
Webbhelix multilineata (Striped Whitelip Snail) – reddish-orange color bands, roundish globose, narrowly reflected.
Go to Webbhelix Page.
F3. Heliciform, reflected lip, imperforate, subglobose to depressed, toothed - Patera (in part), Xolotrema
These are sometimes easily confused in the field. Both have species that are subglobose to depressed and while Xolotrema has a palatal tooth, it is sometimes weak. Use this simple key to distinguish the two genera.
1a. Basal tooth (mostly weaker); parietal tooth slightly curved; palatal tooth lacking or a small bulge. Image below left (or 1st). – Go to Patera Snails Page.
1b. Basal tooth prominent; parietal tooth longer and curved; palatal tooth varies from smaller to stronger, may be recessed. Image below right (or 2nd) - Go to Xolotrema Page.
Patera
Xolotrema
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