Dr. Rob Dillon, Coordinator





Sunday, August 6, 2017

The Most Cryptic Freshwater Gastropod In The World


Through much of the 20th century, the #1 (and possibly only) expert in the biologically fascinating genus Fontigens was the legendary Mr. Leslie Hubricht (1908 – 2005).  Hubricht was trained as a repairman for adding machines and (later) for computers, but spent most of his life travelling around the United States in a van, digging through humus, rolling logs, and peering into holes [1].  He published over 150 scientific papers, primarily on land snails but also on the biota of caves.  Among these were 4 - 5 papers on spring or groundwater-dwelling hydrobiid snails, especially Fontigens [2].

So last month I shared an inspiring story about Lori Schroeder and her discovery of the tiny shells of a mysterious Fontigens species in deposits of storm water flotsam on the margins of several creeks at the Bernheim Forest in central Kentucky [3].  And I mentioned in passing that our good friend Bob Hershler, together with Leslie Hubricht and the cave biologist John Holsinger, had listed nine “recognized species” of Fontigens in their 1990 monograph [4].  Let me back up and expand that statement slightly.

Hershler and his colleagues actually listed ten species, nine of which they “recognized” and one of which was of “questionable status.”  That tenth species, mentioned in a single concluding paragraph on page 43, was Fontigens cryptica.

Leslie Hubricht described Fontigens cryptica in 1963 from under stones in a small spring along the Ohio River in southeast Indiana [5].  He seems to have had at least one living specimen in hand, because he described the animal as “translucent whitish, blind.”  But he immediately confessed, “verge unknown.”  Hershler reported in 1990 that he “was unable to find the snail during two recent visits to the type locality (and nearby localities), nor was it taken during an extensive survey of subterranean habitats in the region (Lewis 1983).”  Hence the uncertainty of its status.

Above I have scanned the 1.9 mm holotype figured by Hubricht in 1963 next to a photo of a 1.9 specimen collected last year by Lori Schroeder.

Notice also the reference to a "Lewis 1983" in the Hershler quote reproduced above.  My attention was called to the existence of this tenth, questionable-status Fontigens by none other than Dr. Julian J. Lewis himself, still very active in karst, cave, and groundwater research in Kentucky today.

By one of those strokes of fortune I have begun to take for granted in my long career, it materialized that in 2016 the Bernheim management engaged Lewis and Associates LLC to survey the subterranean fauna of its caves and springs, and that professional surveys of the entire property had been underway for several months prior to the date that Lori Schroeder first brought her Fontigens discovery to my attention.

So in April Lori offered me an electronic introduction to Dr. Julian (Jerry) Lewis, and we struck up a conversation.  And Jerry confirmed: 
“Bob Hershler and I looked for this species together at the type-locality at a spring in Clark County, Indiana and I've been there repeatedly with no luck.  The spring is high on a bluff overlooking the Ohio River and consists of a hole about the size of one's fist....not much habitat in which to search.  Subsequently I pulled shells of this species from a meter below the surface of the Blue River  -  from groundwater flowing through the hyporheic zone, in the company with a number of other non-cave subterranean species - using a Bou-Rouche sampling pumpwell. 
 I found the snails alive in the interstices of a gravels in a similar situation in a cave in Monroe County, Indiana (near Bloomington) using Karaman-Chappuis extraction. 
 So I suspect your snails are probably a groundwater species, likely living in the interstices of gravel and sand, and will require special sampling methods."
So no, Lewis and Associates LLC had not recovered any Fontigens whatsoever in their survey of the Bernheim property just recently concluded as of this spring [6].   Nor indeed was it Jerry’s expert opinion that we should expect to find any.  Jerry’s studies of the entire regional biota have led him to hypothesize the existence of a single subterranean zoogeographic province extending at least as far south as Mammoth Cave in central Kentucky and as far north as the Blue River drainage of Indiana.  But he has never seen a population of Fontigens cryptica in any cave stream he has explored, ever.  Gravel under a cave stream, yes.  But the little snail is no more an inhabitant of open flowing water under the ground than of open flowing water at the top.  Fontigens cryptica seems to be limited to a third, even more mysterious habitat: saturated interstitial spaces.

I concluded last month’s blog post with a series of three teaser questions: “From what dark recesses of central Kentucky knobland might Lori’s tiny little snails be emanating?  And what might be their identity?  And will Lori Schroeder surrender her quest?”  This month I have addressed questions #1 and #2.  Next month I will address #3.  And here’s your teaser.  No.


Notes

[1] He stood silently in the lobby outside AMU meetings in the 1970s and 1980s, wearing a stiff dark suit.  I wish I had gotten to know him.

[2]  Gerber, J. (2010)  Leslie Hubricht (1908 – 2005), His publications and new taxa.  American Malacological Bulletin 28:15-27.

[3] Lori Schroeder’s Tiny Snails [17July17]

[4] Hershler, R., J. R. Holsinger and L. Hubricht (1990)  A revision of the North American freshwater snail genus Fontigens (Prosobranchia: Hydrobiidae).  Smithsonian Contributions to Zoology 509: 1 – 49.

[5] Hubricht, L. (1963)  New species of Hydrobiidae.  Nautilus 76: 138 – 140.

[6] Only a single freshwater gastropod was listed among the 61 species documented by Lewis and Associates - Lymnaea humilis in a seep spring.