Monday, November 22, 2010
Unknown Valloniidae species
By Sunday I was feeling antsy to get outside. I was sure I was going to get up early and hit Plymouth Flats for migrating waterfowl, gulls, Snow Buntings, and possibly something juicy like a Lapland Longspur. However my flu still had the best of me and I slept in. Eventually by the afternoon I decided I'd take my chances and I'd make my older daughter come with me to do a little hiking around in Frances Slocum State Park.
We didn't stay long but I identified some places that I think will be great for snails come the springtime. Specifically I found some rocky outcrops that I didn't even realize were there when my only focus was on birding.
Checking a couple places I found what I thought was my only snail, a Stenotrema hirsutum (Hairy Slitmouth). I picked it up and put it in a little baggy I had. I also decided to grab a pinch of substrate by it to accompany it on the way home. Fast forward to when I got home and looked at the bag. I noticed a tiny little snail in the dirt.
This snail has a 1.7mm diameter, is umbilicate, obviously has ribs, and has about 3 1/2 whorls. It also has what I think is described as spiral striae (lirate?). The snail itself is mostly colorless but its tentacles are clear with black flecks throughout. I'm fairly sure it is in the family Valloniidae but I'm having trouble getting to species. So I'll talk out my thought process via this blog.
So first things first, I got it to the family basically just because I've had my nose in the books for the past couple months, thumbing through trying to get my bearings. I've paged through looking for other similar families but seem to come up empty.
That brings me to what it could be specifically. Top contenders in my mind seem to be Planogyra asteriscus, Vallonia costata, and Vallonia perspectiva.
Of those three, only one is listed in Land Snails of Limestone Communities and Update of Land Snail Distributions in Pennsylvania (Pearce): Vallonia costata. So it seems like the obvious answer-- after all, I'm a newbie and I doubt I'm finding state records at this level of my knowledge. The one problem is that this snail does not exhibit an expanded lip. Also, it is a little too small. So, perhaps, it is that this is an immature Vallonia costata who needs to grow and develop the telltale lip. But it does mention the spiral striae in Pilsbry.
Planogyra asteriscus measures 1.7 to 2mm and, according to the 1960 Burch key, its range is Maine, Massachusetts, New York, and Michigan. We're an hour away from New York state, so it's a possibility.
Vallonia perspectiva is 2mm or less and its range (again, according to the 1960 Burch key) is New Jersey to Alabama, west to Minnesota, Utah, and Arizona. So, again, it's a possibility, even if not on the state list. It doesn't have that expanded lip.
So that's that. Likely an immature Vallonia costata, maybe something else. I'm going to hold onto it in a petri dish terrarium and see if it grows any and I'll post on this blog any definitive answer.