General Recognition of Spot snails and Tentative Key to Species
Characters: tiny snails (~1 - 1.5 mm in diameter); subglobose to depressed; simple lip; widely umbilicate; radial striae; about 4 whorls; thin, unreflected lip
Comparison: a hand lens or better is needed to distinguish the features in the key: teeth, riblets, and striae. Oesch et al. (2013) has great images of the surface sculpture. Also see Punctum in Hotopp et al. (2013)
Habitat: in general - woodland habitats among leaf litter and woody debris, especially if substrate is well‐decayed, under rocks and such.
Status: widely scattered, likely under collected, basically status not known.
Key to Punctum based on Burch (1962) and Oesch et al. (2013) and excluding Punctum pygmaeum.
1a. Shell aperture without teeth or lamina – go to 2
1b. Shell aperture with a broad lamina – Punctum smithi
2a. Shell with major riblets low and relatively closely spaced with 1–3 minor ridges lightly crossed by spiral striae, not forming distinct microscopic squares – go to 3
2b. Shell with major riblets high and widely spaced with 3-7 minor ridges crossed by spiral striae forming distinct microscopic squares. – Punctum vitreum
3a. Shell somewhat depressed; umbilicus narrower – Puctum minutissimum
3b. Shell more depressed; umbilicus wider – Punctum blandianum