Wednesday, February 10, 2016

Five minutes under a rock

Curiosity is a funny thing and I hope I never lose it.  While walking through a field, I stopped to photograph a lichen growing on exposed dolostone rock.  Although locally common, statewide it is a very uncommon lichen called Psora pseudorussellii.  Pictured below, it is a squamulose lichen attractively colored with red apothecia (red discs which are the fruiting bodies of the fungus).  

Psora pseudorussellii

After photographing the lichen, I noticed a smaller rock nearby, a little bigger than a football.  Like a dog to a fire hydrant, I am attracted to rocks I think I can lift.  I can't seem to shake the curious question of "what is under that, and every rock"?   And of course, there is always the chance of finding something I haven't seen before, so why not take a look.

The rock.  A piece of Peebles dolostone.
So I took about five minutes to quickly look and see what animals I could find (at least visible to the naked eye).  Almost immediately, two critters disappeared into the cracks of the ground before I could get a picture.  One was a common exotic earthworm called Lumbricus rubellus.  Everyone has seen this worm before, and it is not too hard to identify if you can recognize its faint red wine color.  The second was a sowbug or wood louse (sowbugs can't roll into a ball like pilbugs, Armadillidium sp., but look similar) called Trachelipus rathkei.  T. rathkei is a fast, 2-tailed sowbug and also an exotic species.  Both of these are expected under rocks at the "Edge".

But a few animals stuck around long enough to photograph, or proof of the animals existence was there.  A female wood roach, Parcoblatta sp., stood still long enough for a pic.  A few leafhoppers showed up after I lifted the rock.  These little hoppers from the genus Erythroneura jumped into the soil under the rock, but I think were in the grasses beside the rock and not underneath.  All pictured below.

  Parcoblatta sp. of wood roach commonly found under rocks and logs on the preserve.

Erythroneura sp. leafhopper showing very attractive pattern.  Many leafhoppers are just as showy as the prettiest my opinion.

Another Erythroneura  leafhopper, barely a millimeter in size
What got my attention in those few minutes of looking under that rock were the amount of micro-snails (<5mm) and/or snail shells on the rock or in the dirt underneath.  I quickly counted the species I could identify, and collected a couple of shells I knew would require a scope for identification.

If you look closely you might find snail shells under the rock
Most shells will blend in well with the soil or rock, so you need to search carefully.  Here a Catinella vermeta blends in.
Many small land snails can be found under rocks and woody debris on the ground as well as grass thatch where it meets the soil.  This particular rock had 14 individual snail shells found within this short search time.  None of them larger than 4 millimeters.  Luckily, land snails are easily identifiable by using their shell, so if the animal is dead, you can still identify it to species.  They were: the white-lipped dagger, Pupoides albilabris, 2, the armed snaggletooth, Gastrocopta armifera, 4, the minute gem, Hawaiia miniscula, 3, the suboval ambersnail, Catinella vermeta, 2, the wild hive, Euconulus chersinus, 2 and 1 small unknown Gastrocopta.  

2 snail shells.  The one on the right shows the "teeth" of the shell opening giving reason to the common name armed snaggletooth snail.
Armed snaggletooth, Gastrocopta armifera shell
 I wanted to take a closer look at the small unknown Gastrocopta. I was hoping it was the rare species Gastrocopta rogersensis, which was newly described in 2001 in Iowa, only to be found a couple years later here at the Edge by one of it's author's Jeff Nekola.  The range of this species is hundreds of miles west of the Edge, making his find a disjunct anomaly like so many other species found on this preserve.  Since his discovery of this overlooked land snail, I have found them in 2 other prairies on the preserve.  But it would be nice to extend its range within the preserve.

White-lipped dagger, Pupoides albilabris shell hiding in the mud.
Once back in the lab, and the few collected snails were placed "mouth up" under the dissecting scope, I could easily see "tooth" features in the opening of the shells.  My curiosity driving me to wonder what was under that rock has led me to an exciting find (at least to a small circle of maloco-phile folks).  I believe the mystery snail is Roger's snaggletooth (Gastrocopta rogersensis), the newly described species mentioned above.  This adds a fourth location of this snail on the preserve.

Here you can see the size difference in three of the shells. Gastrocopta rogersensis (>2mm), Hawaiia miniscula (2mm) and Pupoides albilabris (4mm).  So 4mm is a big snail under this rock.
These were just the larger animals I could see in a five minutes.  Just imagine how many creatures there really are if you could count the micro inhabitants under this rock.  I need to remember this when I am out looking under rocks and logs.  I should be a little more deliberate when putting a rock back in its place.  And maybe, hiding under the next piece of debris, an un-described species will be found, unknowingly waiting to be discovered.  Just curious.

Posted by:  Mark Zloba