An endemic radiation, no matter how small

Wanted: Collaborator.  Cranky old malacologist in the twilight of his dubious career seeks bright young evolutionary scientist with working laboratory and good molecular skills.  Collaboration to explore a previously unappreciated endemic radiation of hydrobioid freshwater gastropods, with potential to yield insights into the tectonic history of North America.  Apply within.

I was born a child of the American Family Road Trip.  My earliest memories of the wide world around me came from the rear-facing jump seat of a red-and-white 1959 Chevy station wagon, riding south up old US-11 toward Grandma’s house.  And vividly I remember billboards advertising the show caves – Grand Caverns, Skyline Caverns, Endless Caverns, and the crown jewel, Luray.  Hear Rocks Sing? Wonderful.

The Great Valley, with Show Caves [1]

We travelled up and down The Great Valley of Virginia.  Dad liked to hit the road before the crack of dawn, so we’d begin our day in the Shenandoah drainage, all those pretty little rivers under all those picturesque little bridges flowing north down to the Potomac.  But soon we’d crest a low rise and enter the James River drainage – the “Beautiful James,” Dad called it – running east toward Richmond.  Another 30 – 40 minutes up US-11 we’d crest another almost-imperceptible rise and enter the Roanoke Drainage, flowing SE toward North Carolina.  Then up a long grade to the New River Valley – a high plateau, actually – flowing mysteriously west toward the Ohio.  And then finally, imperceptibly, we’d enter the headwaters of the Tennessee River, flowing south.  That’s five very different river systems, each with distinctive biotic elements, flowing to all five points of the compass, draining from The Great Valley of Virginia.

And although the geology over which we traveled was complicated, the predominant bedrock has been, for quite a few years now, Paleozoic limestone.  And the hills are honeycombed with caves.  For every big show cave my family visited, there are a thousand caves that tourists cannot [2].

Indeed, my childhood friends and I were familiar with one closed-off cave at the City of Waynesboro’s Coyner Springs Park, where the Dillon family cooked out many a hot summer’s evening.  And I probably wasn’t much more than six years old when I first held in my tiny hand an even tinier hydrobioid snail of the genus Fontigens.  Those little snails covered the watercress like pepper in Coyner Springs run, the city’s water supply, where all the kids invited to everybody’s birthday party splashed barefoot through the ice-cold, crystal-clear waters.

Tom Malabad at Big Entrance Crawl Cave, Scott Co.

I couldn’t identify those bazillions of teensy little black snails, any more than I could identify any of the other familiar freshwater gastropods of my youth.  My readership of long tenure will be well-acquainted with my childhood frustrations in that regard, and how such frustrations ultimately framed my entire professional career [3].  In fact, I still couldn’t identify the population of hydrobioid gastropods grazing across the water cress at Coyner Springs Park as late as 1979, when I carried a ball jar full of them to my fellow graduate student Bob Hershler, laboring at the bench beside me at the Academy of Natural Sciences in Philadelphia.

Bob scratched that particular itch in 1990, with his admirable “Revision of the North American Freshwater Snail Genus Fontigens,” published together with legendary cave biologist John Holsinger and legendary malacologist Leslie Hubricht [4].  In addition to my childhood playmate Fontigens nickliniana, Bob and his team recognized four other species in The Great Valley, the widespread F. orolibas and three with more restricted ranges: F. bottimeri, F. morrisoni, and F. tartarea [5].  Bob listed a sixth species, Fontigens turritella, from just over the mountains in adjacent West Virginia.

Although all six of those species can be found in subterranean waters, the first four were described from above-ground springs, F. tartarea and F. turritella apparently the only obligate cave-dwellers.  And by 1989, Bob had described a seventh obligate cave-dwelling hydrobioid from The Great Valley very closely related to Fontigens [6], Holsingeria unthanksensis [7].

From Hershler [4,7]

Bob Hershler ranked among the best malacologists of our generation, and I was pleased to watch from the sidelines as he worked his way through the North American hydrobioids, not just the Fontigens of the Great Valley, but all of the hydrobioid snails all across this great wide continent 1985 - 2017.  But then, he disappeared [8].  And the snails did not.

At this point I must beg your indulgence for a flashback, to the era of the Second Great Environmental Awakening [9].  In 1979, the Commonwealth of Virginia joined a growing list of states [10] with special laws on the books directed toward cave protection.  No other state in the union, however, could boast at the time, nor can boast today, of a dedicated Karst Protection Program, staffed by biologists specifically charged with the inventory and protection of subterranean fauna associated with caves, karst and other groundwater environments, including springs.  My good buddy Wil Orndorff was hired as Karst Protection Coordinator for the Commonwealth of Virginia in 2001.

Will Orndorff

I first met Wil on the “Cave Snail Adventure” I described in the columns of this blog back in 2007 [22Aug07], leading a hunt for Holsingeria in Unthanks Cave, way down in the SW tip of the state.  Back in those days, the emphasis of Wil’s program was on karst groundwater protection, primarily funded by an EPA Clean Water Act grant.  They subsequently went through what Wil describes as “very lean years” during which time their funding was primarily from studies of the White Nose Syndrome of bats.  But the funding situation improved in 2013, at which point they began a systematic inventory of the biota of Virginia caves and karst environments in earnest.  Tom Malabad joined the full-time karst team staff in 2016.

So in November of 2018, about a year after Bob Hershler retired, I was pleasantly surprised to receive an email from Wil, with Tom on the CC line.  The subject line read, “Some Virginia cave and spring snail collections that need you.”

The tale of those N = 61 Virginia-collections-that-needed-me was told in my essay of [9Jan24], posted on this blog just a bit over two years ago.  The collection dates on the meticulously-documented labels they bore were almost entirely 2013 – 2018 [11].  My loyal readership might remember that, setting aside the subset containing only land snails and the subset containing only freshwater gastropods typical of above-ground habitats, I was left with a still-remarkable 20 samples of tiny hydrobioid snails on my bench.

Tom Malabad

That first batch of 20 included 11 populations of F. orolibas, 3 of F. bottimeri, 2 of F. morrisoni [12], 2 of Holsingeria, and two populations of Fontigens bearing shells unlike anything I had ever seen before.  So I got back in touch with Wil and Tom, and they sent me a second batch of 16 samples in September of 2019, and a third batch of 10 samples in February of 2020.  And in that February batch, I found what looked like a third undescribed species of Fontigens.  Oh, for Heaven’s sake.

I hate describing new species, and simply do not have the wherewithal to do so.  I have been retired for ten years now, working off plywood benches laid across milk crates in my son’s old bedroom.  It is irresponsible in this day and age to describe new species without genetic data to confirm, and that chapter in the book of my long and checkered career has long turned.

 

But by the Blessings of Divine Providence, completely independent of all the Fontigens my buddies Wil and Tom were sending me from the Great Valley of Virginia, I was also involved at that time in a separate project on Fontigens cryptica in Kentucky [13].  And my Kentucky collaborators and I had found some funding.  And I had interested our good friend Hsiu-Ping Liu out in Colorado to do the genetic work.  And we were able to piggy-back the Virginia Fontigens work on the Kentucky Fontigens funding.

 

The upshot of all this churn was that in late 2023 the team of Dillon, Malabad, Orndorff and Liu described three new cave-dwelling Fontigens from The Great Valley of Virginia: Fontigens hershleri, F. benfieldi, and F. davisi [14].  That brought the total number of teensy-little phreatic hydrobioid species under the rolling hills and gentle mountains that disappeared into the blue haze behind my dad’s 1959 Chevy Station Wagon up to 7 + 3 = 10.

From Dillon et al. 2023 [13]

One would think that would be enough, am I right?  Surely those 61 + 16 +10 = 87 samples that Wil and Tom had sent me by early 2020 would pretty much scour all the tiny little ghostly-white gastropods out of all the caves, springs and seeps in the entire Commonwealth of Virginia, yes?  And perhaps our good buddies might turn their attention to the 99.99999% of the waters of the Old Dominion a bit easier to sample?  One would be wrong.  Stay tuned.

 

Notes:

 

[1] Key to the Show Caves of The Great Valley: (A) Crystal, (B) Dixie, (C) Endless, (D) Gap, (E) Grand, (F) Luray, (G) Natural Bridge, (H) Shenandoah, (I) Skyline.

 

[2] Here’s a verbatim quote from Wil Orndorff: “Conservatively, as of today approximately 3,500 known caves in Virginia meet the international definition of a minimum length of 5 meters, with 368 of them designated as significant under the Virginia Cave Protection Act.”

 

[3] For more on the frustrations of my nerdy youth, see:

• The Clean Water Act at 40 [7Jan13]
• To Identify a Physa, 1971 [8Apr14]

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

 

[5] As of 1990, Hershler et al considered F. tartarea restricted to West Virginia.  A population of the species was not discovered in a Virginia cave until 1994.

 

[6] Technically Bob assigned Holsingeria to the Lithoglyphinae (later Lithoglyphidae) on the basis of penial morphology.  But it’s a Fontigens.  Just look at it, for heaven sake, and use your biological intuition.

 

[7] Hershler, R. H. (1989) Holsingeria unthanksensis, a new genus and species of aquatic cavesnail from eastern North America. Malac. Rev. 21: 93-100.

 

[8] For an appreciation of the career of Dr. Robert Hershler, see:

• My Buddy Bob [6July22].

[9] I would date the “First Great Environmental Awakening” from the creation of Yellowstone National Park in 1872 to approximately 1916, the creation of the National Park Service.

 

[10] Off the top of his head, Wil could think of eight states with cave protection laws: Virginia, West Virginia, Kentucky, Tennessee, Georgia, Arkansas, Missouri, and Pennsylvania.

 

[11] One collection date was 1987, one was 2008.

 

[12] One of those morrisoni was misidentified.  The correct identification was F. tartarea.  I didn’t catch my error until earlier this year, in fresh samples collected by the team 2020 -2025.  More about which next month.

 

[13] The story of the rediscovery of Fontigens cryptica was a fascinating one, which I serialized over a stretch of five years:

• Lori Schroeder’s tiny snails [17July17]
• The most cryptic freshwater gastropod in the world [6Aug17]
• Not finding Fontigens cryptica [6Sept17]
• Finding Fontigens cryptica [3July19]
• Startled by Fontigens, sort-of, I suppose [9Aug22]

[14] Dillon, R.T., Jr., T.E. Malabad, W.D. Orndorff & H-P. Liu (2023) Three new Fontigens (Caenogastropoda: Fontigentidae) from caves in the Appalachian Ridge and Valley Province, Virginia. Pp. 283 - 306 in Dillon, R.T., Jr. et al. The Freshwater Gastropods of North America Volume V: Ohio, Cumberland, and Tennessee River Systems. FWGNA Press, Charleston.  For a review, see:

• Three New Fontigens from Virginia [9Jan24]