Ravenswood Media

Antroselates spiralis
© Stephanie Clark

Elusive Snail Species

by Stephanie Clark

I work on the taxonomy and systematics of land and freshwater mollusks, especially those found in the US and Australia. One of the groups I specialize in, are the freshwater and estuarine snails of the family Hydrobiidae (Pebblesnails). This family is very diverse and found around the world, they tend to have very narrow ranges often restricted to a single springs or streams. The family is particularly diverse in the US with over 300 named species and it is estimated that at least that number remain to be discovered and named. Several species are adapted to life in caves, including the caves of Kentucky, Indiana, Illinois and Missouri. The largest of the cave snails found in the US is Antroselates spiralis (Shaggy Cavesnail) which is known from central Kentucky and southern Indiana. It is globally rare and indicative of high water quality.

Stephanie Clark
Left to right: David McGowan,
Stephanie Clark, and Allen Pursell
© Ken Redeker
Last August, there was an opportunity to undertake a small expedition to find this elusive species in some of the springs flowing into the Blue River of southern Indiana. My friend Dave from Ravenswood Media introduced me to Cassie Hauswald and Allen Pursell of The Nature Conservancy. Cassie is the aquatic biologist for the Blue River Office and specializes in malacology. In the early morning we set off to examine three springs and a cave near Corydon, Indiana.

The first location we tried was Firetail Spring, a very small spring that flows into the Blue River. After  30 minutes of examining the undersides of rocks in the head of the spring two specimens were discovered. The presence of this species is a good sign for the water quality of Blue River.

The populations of A. spiralis are known from two different drainages separated by about 100 km. My suspicion is that the Indiana populations may actually represent a separate but closely related undescribed species from the one in central Kentucky. One of the characters that distinguish this species from other related hydrobiids (pebblesnails) is that the shell has small raised spiral ridges. One examination of the two specimens found these spiral ridges did not appear to be present. Now there are several possible explanations for this apparent difference, not the least of which is population variation. Needless to say this is a very interesting preliminary finding and hopefully later this year additional samples can be obtained to study the shell, reproductive anatomy and DNA of these fascinating animals and hopefully resolve the taxonomic questions.

Merlin Tuttle
David McGowan and Cassie Hauswald
© Ken Rederker
Merlin Tuttle
© Al Rasho