Tuesday, October 25, 2011

Visualizing Pennsylvania Snails

Making a living on the web as I do, I find it inconvenient to have to look thru pdfs for data that is ripe for interactive visualization. So I took Pearce's Land Snails of Limestone Communites and Update of Land Snail Distributions in Pennsylvania and added in my own records to create an interactive map of the counties.

Don't know if it works in Internet Explorer, but it works in Chrome and Firefox. Seriously, it's 2011. There is no reason to use Internet Explorer. Let me get on my soapbox and say that Microsoft doesn't give a damn about user experience, web standards, or modern web practices. Use Chrome-- it's the best browser out there. Firefox is fine, too.

Here's the link:

Monday, October 17, 2011

Tricky Triodopsis

I've featured Triodopis species here before but I wanted to drop a quick not on identifying the congeners Tridopsis tridentata (Northern Three-tooth) and Triodopsis juxtidens (Atlantic Three-tooth). Later I'll update this article with some comparison photos but here is a mnemonic to keep in mind:

ATlantic is AT or Above,
Northern is southern.

What's being referred to here is which direction the distal edge of the palatal tooth points in relation to the upper palatal tooth-- the key to differentiation (morphologically).

You can read where I gleaned this identification information at the Carnegie site.

The real reason for this article is that I need a device for myself as I think I may be confusing the two. Often. The article says that 'ridge-and-valley' is mostly Atlantic but I've called most Northern. And, earlier today, I was at Frances Slocum and think I may have seen both in close proximity and couldn't remember for the life of me which was which. But maybe there weren't both. I have to be a little more intellectually vigilant sometimes. However, Slocum is just chock full o' Triodopsis so I don't pay that much attention. It's a 'hiding in plain sight' sort of thing.

I'll try to post pics soon to this article to illustrate the point.

UPDATE: No photos yet but I looked through shells I've collected heretofore and they are all indeed T. tridentata. I believe the shells I collected (and live individuals I saw) on the other side of Slocum are T. juxtidens (but I'm in Ithaca right now and don't have them on me) but that could mean both species are present in the park, albeit different sides of the lake. I don't see any appreciable difference in habitat so I find it fairly interesting.

Sunday, October 16, 2011

Two Cool Finds at Hickory Run State Park

I finally got a chance to run to Hickory State Park in Carbon County, PA over the weekend. During the course of a few hours I stopped in 4 locations along the drive to do some snailing. The first few stops had me thinking it was another common, Northeast Pennsylvania snailing day. Most prevalent were Euchemotrema fraternum (Upland Pillsnail). At each stop I must have counted 10 to 20, mostly juvenile (juveniles identified by proximity to adults). Also common were what I called Philomycus flexuolaris (I don't think they were Megapallifera mutabilis, I remember a lighter foot fringe).

Pallifera species

At the first stop my first exciting find was a Pallifera species slug. My last post (wow, way back in June...) was about Pallifera ohioensis (Redfoot Mantleslug). This slug is a different Pallifera. Now, I have to assume it's probably a Pallifera dorsalis (Pale Mantleslug) but I'm not so sure. Pilsbry speaks of a mid-dorsal line of dots, but this slug lacks that. The rest of the descriptions seems pretty close. The slug in my possession is at times gray-blue and others reddish-tan. It has whitish speckles on the mantle which become little cinnamon flecks as above the foot fringe. It measures 10mm so I assume it's immature.

Interestingly I was able to find a few other photos of slugs online with close to the same markings (here and here and here). The biggest difference with mine is the darker markings on its head and tail.

UPDATE: Here it is the next day and I found a similarly marked Pallifera sp. at Frances Slocum State Park crawling on an empty Neohelix albolabris shell. Under the microscope, though, this one exhibits a faint mid-dorsal line of spots but lacks the darker markings (still dark over eye stalks). This slug is only 7mm.

Helicodiscus parallelus

The last stop of my day was where all the action was. Along a single fallen tree I found: more Euchemotrema fraternum, Discus catskillensis, Ventridens ligera, and possibly Zonitoides arboreus (pretty much the same snails I see all the time in my own county). But I also found what I thought was an empty Helicodiscus parallelus. I threw it in one of my little tupperwares I collect in and went home. Today, while inspecting it under the microscope I thought it looked as if there could be an animal inside. Adding a leaf of lettuce and a spritz of water I left it to sit. Later I came back to it and, sure enough, it was crawling around. 

This little snail measures 3.25mm. The coolest thing about this is that it's a little blind snail. If you look closely at the photo you'll see that there seems to be no eyes at the top of the tentacles where you normally see them on other snails. I've found empties before in stream drift in Ithaca, but this is my first encounter with a live animal.

Land Snails of Limestone Communities and Update of Land Snail Distributions in Pennsylvania (Pearce)
Funny enough, although the snail has widespread records, it was missing from Carbon County. I added it in green in the above map.