Monday, October 18, 2010

Ventridens ligera : Globose Dome

Next on my list of identified Luzerne County land snails is Ventridens ligera, commonly known as the Globose Dome. These snails (or at least their shells) were under pretty much every log I lifted along the railroad tracks in West Wyoming near Airport Gravel and Sand.

Using Birch's 1962 key I came to the conclusion of Vitredens demissis (Perforate Dome). However, after reading more about the species on the Carnegie website I changed my mind. First, Vetridens demissis was completely left off his 2006 county distribution list. Second, in the account I learned that juveniles of Vitredens demissis have a basal lamina. After reading that I checked some of the juvenile shells I picked up and found no basal lamina leading me to rethink the identification. What I realized is that I still don't have a good grasp on what would constitute slightly depressed versus globose.

From there I believed it to be either Vitredens interdextus (Pyramid Dome) or Vitredens ligera. I was leaning towards Vitredens ligera, but not totally sure of myself after the misdiagnosis. So I shot an email off to Carnegie Mollusk Curator Tim Pearce to ask a few questions about Ventridens and identification in general.

He pointed out that Ventridens intertextus have a spiral striae (a fact I missed in the key) and that the juveniles have an angular periphery. So the identification was clinched in my mind as Ventridens ligera.


Range map from Land Snails of Limestone Communities and Update of Land Snail Distributions in Pennsylvania (Pearce) with my own county added to range (in orange). Formerly unknown to Luzerne County.

Identification notes:
Height: 10mm range
Width: 10mm range
Shell: Narrowly Perforate Heliciform
Lip: Thin, Unreflected
Apertural Teeth: None
Aperture: Ovate-lunate
Whorls: 6
Other: Pedal Groove

Location Found:
Along railroad tracks near Airport Gravel and Sand
West Woming, PA- Luzerne Co.
41.307306097168215, -75.85408061742783

1 comment:

  1. Have you found any pictures showing the spiral striae of Ventridens intertextus? Trying to ID one of my own (, and your post is very helpful, but would be nice to see an image. Mine does seem super glossy like yours, so maybe also V. ligera.