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 1959 Chevy station wagon [1], 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 [2]

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 [3].

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 [4].  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 [5].  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 [6].  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 [7], Holsingeria unthanksensis [8].

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 [9].  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 [10].  In 1979, the Commonwealth of Virginia joined a growing list of states [11] with special laws on the books directed toward cave protection.  No other state in the union, however, could boast at that 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 the team initiated 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 had 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 [12].  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 [13], 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 [14].  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 [15].  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] My mother named that car "Red Wing," after one of her favorite ballads.  She loved to sing that song!  The whole Dillon family did.

[2] 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.

 

[3] 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.”

 

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

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

[5] 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.

 

[6] 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.

 

[7] 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.

 

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

 

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

• My Buddy Bob [6July22].

[10] 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.

 

[11] 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.

 

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

 

[13] 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.

 

[14] 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]

[15] 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]

Nevada Desert Worldview Collision

Editor’s Note – Last month we explored the relationship between the worldviews of Art, Science, and Public Policy.  This month we push onward into the worldviews of Business and Commerce, about which I know even less, as we shall see.

Sometimes, I identify snails for money.  I hasten to add that I am always happy to do so for free, if your specimens (or jpeg images thereof) are accompanied by good data, especially if the request is courteous. But sometimes I receive requests from environmental consultancies, who have themselves been contracted to collect the specimens in question, and they expect to pay me as a subcontractor.  Fine, I’ll take your money.  I charge $25 per sample.

Pyrgulopsis kolobensis, Nevada

So in the spring of 2020 I received my first inquiry from an officer of an environmental consulting operation in Colorado whom I will identify as Ms. Nickle-Chaser, or N-C for short.  She wrote a single line over a forward from a mutual colleague recommending me to identify “springsnails in Northern Nevada,” simply adding, “Would you be able to help?” 

I replied in the affirmative.  And there followed the usual back-and-forth about contracts, work authorizations, chains-of-custody and so forth.  I am an utter foreigner in the world of business and commerce – I understand that the motivation is money but cannot imagine how anybody could be so motivated.  I am able to cooperate in such situations as a dog commanded to sit and shake.

Nor, in retrospect, did Ms. N-C understand the language of science and technology in which I addressed her.  Here is a quote from quite early in our negotiations, 29Apr20: 

"I usually work with samples preserved in 70% ethanol, although higher concentrations are better.  The USPO pitches a fit about shipments containing ethanol, however, as do some of the private carriers, sometimes.  So a trick is to put the snails in a little unbreakable vial full of ethanol, and then stuff cotton down in the vial, and then pour off any excess ethanol.  So you can reassure the clerk that your shipment does not contain any liquids.  Just wet cotton, right?"

So, a few weeks later I got an email heads-up from N-C that a 15” x 12” x 15” box weighing 19 pounds was on its way from Denver to Charleston, by UPS next-day air.  And she noted, “Ice will be partially melted I expect.”  Nineteen pounds flown across the country by overnight express?  Good grief, I thought to myself – how much must that cost?  Surely whatever I charge for the identification of a few samples of snails will be dwarfed by the cost of their shipping, yes?

 

And indeed, six samples did arrive quite promptly the following evening.  Each was contained in a wide mouth 500 ml Nalgene bottle of (what smelled like) denatured ethanol, packed in ice, packed in a cooler, double-bagged, packed in a box, elaborately taped, dripping a puddle on my front porch.

 

I was disappointed not to find any locality data for the six samples – just number codes written on the bottles.  Looking back at our early correspondence, I probably should have emphasized the importance of such data with greater urgency.  I do save data on the distribution of all freshwater gastropods collected across the entirety of North America into the FWGNA database.  My excel spreadsheet has 13 columns, including not just state, county, latitude and longitude, but also collector and date of collection, and those data are just as important as the sample specimens themselves, and indeed the latter worthless without the former.

Central Eureka County, Nevada

So I requested locality data in my email confirming receipt, and Ms. N-C replied with lat/long coordinates the next day – six tiny green cracks in the arid Cortez Mountains of Eureka County, Nevada.  And I went to work.

 

The samples turned out to be quite various.  One contained a beetle and a pebble.  Two were unpicked bulk samples, one of which ultimately proved to include snails, and the other of which did not.  And three were clean samples of snails.  These were my results for the four samples that contained snails, as I ultimately reported them on 8June20:

• Three of your samples contained Pyrgulopsis kolobensis, one of the more widespread springsnails of the Great Basin, ranging eastward into Utah.
• One of your samples contained Pyrgulopsis gibba [1], also widespread, ranging west into California.
• Two of your samples also contained common pulmonate gastropods, Lymnaea cubensis and Physa acuta.

And I concluded, “Attached you will find an excel spreadsheet with my detailed results, and an invoice, in the amount of $125.” [2]

 

This information apparently satisfied my customer, and my customer’s client as well.  For in the spring of 2021 I received a second inquiry from N-C, which I was again happy to answer in the affirmative.  And negotiations were exchanged, very nearly identical to those we had exchanged in 2020.  N-C had originally expected to send me “several samples in the June or July timeframe,” but her field trip was slightly delayed.  Here is the message I received 24July21: 

"Hi there. I just wanted to let you know that we are going to begin spring sampling for snails starting tomorrow and will be shipping them toward you hopefully on the 29th but may ship it out on the 30th. We will try to overnight that and get it to you rapidly.  Thanks."

The next morning I sent Ms. N-C a reassuring reply, to the effect that I am retired, and in no hurry whatsoever.  And in boldface I asked her this question: “Why are you planning to send your samples to Charleston by overnight express?  Why not good, old-fashioned US Snail-mail?”  And I signed it, “What is your hurry? Rob”

 

At 10:30 Friday morning 30July21, a three-foot cooler appeared on my doorstep, containing 10 double-bagged 500 ml Nalgene bottles of what smelled like denatured ethanol packed in ice.  Good God, that thing must have weighed 40 pounds.  I acknowledged receipt immediately, reminding her about the necessity of locality data, for which (one would think) there might have been room in each of the 500 ml bottles, somewhere.  And in her reply of 11:46 AM, N-C answered the question I had asked her five days earlier as follows: 

“Years doing water quality monitoring taught me the best way to send samples.  Those suckers are worth thousands of dollars, when you factor in time spent planning, surveying, shipping, etc.  It would be a bummer to have to go back out and resample on our dime.”

And she did follow up with the locality data.  And at that point, there was no reason to argue with her about the 40-pound overnight shipment.  I suppose I might have reviewed some of the differences between a sample of water and a sample of preserved freshwater gastropods, and explored the consequences those differences might suggest in shipping methodology.  But her frame of reference was monetary, not scientific.  She was speaking a language that I did not understand, and I understood that.

 

So again, I went to work.  All ten of the 2021 samples also turned out to have been collected from Eureka County, Nevada, but from wetter environments than the 2020 samples.  Most of these were from ponded springs in pastureland, impacted by cattle.  Only two samples contained hydrobiids (P. kolobensis) but all ten contained pulmonates, with six species represented [3], most interestingly Lymnaea (Galba) bulimoides [4].  I sent Ms. N-C a spreadsheet, a formal report, and an invoice for $250 on 5Aug21, and received payment on 17Sept21.

Lymnaea (Galba) bulimoides, Nevada

And my satisfied customer contacted me again in the springs of 2022 and 2023, and very similar business transactions occurred.  Big coolers appeared on my doorstep by overnight express, filled with ice and Nalgene bottles but not locality data.  The 2022 shipment, ten samples collected from the vicinity of the town of Beatty in Nye County, Nevada, were almost entirely of Physa acuta, with a sprinkling of L. humilis.  For some reason it especially irritated me to see hundreds of dollars spent shipping trash snails across the country by overnight express.  But on the other hand, I was beginning to accumulate a nice collection of free coolers.

 

At this point I feel called to set aside the orderly unfolding of my narrative, and confess a personal shortcoming.  Not only are the language, values, and culture of the World of Business foreign to me, I am unsympathetic to them.  I have spent my entire career with my right foot firmly planted in the World of Science, and my left toe delicately touching the World of Public Policy [5].  In both of those worlds, Pyrgulopsis and Physa are entirely different things.

 

As a scientist, I know that Bob Hershler kicked the five (mostly eastern) species of Pyrgulopsis listed in the (1980) Burch cannon [6] up to 54 (western) species in 1994 [7], and that by the end of his career, Bob was recognizing 126, mostly on the basis of negligible DNA sequence divergence and penial characters of dubious biological significance [8].  My left toe tells me, however, that the Nevada Division of Natural Heritage lists 76 nominal species of Pyrgulopsis within its vastly trapezoidal borders, the great majority of which are ranked “G1 = critically imperiled globally.”

 

So, if Ms. N-C were to discover a population of 3 mm prosobranch snails in a Nevada spring, I might be able to understand some special care in their shipment to an expert across the country.  But if she were to find a population of “those suckers” bearing thin, sinistral shells in the ditch behind a McDonald’s restaurant licking the special sauce off the back of a Big Mac wrapper, she could just send me a jpeg, am I right?  But please, in any and all cases, regardless of what those suckers look like, is it too much to ask for locality data?

Charleston.  August 31, 2024

We were headed for a worldview collision.  On 17July24 I received what had (by that point) become my annual greeting from Ms. N-C, reporting that she had a “very small project in Nevada that needs a snail ID on perhaps 3 samples,” and asking if I would be able to assist.  And I replied that I would be happy to help as usual.

 

And on 31Aug24 a hefty 1.5’ x 2’ x 2’ box arrived with a thump on my doorstep, overnight air from Nevada.  It weighed in excess of 13 pounds.  Inside the box (1) I found four layers of plastic bags (2): damp, wet, soaked, and dripping puddles on my wife’s dining room table.  And inside the fourth bag was (3) a little red cooler exorbitantly taped with three layers of a deceptively-strong clear packing tape that defeated every knife in my kitchen.  And sloshing about within that cooler was (4) a single 500 ml Nalgene bottle of alcohol.  And inside that bottle of alcohol, I found (5) one, single little shell.

 

Not a snail, mind you, a shell.  A single lymnaeid shell of 5.5 mm standard length, translucent in its pristine emptiness.  It had belonged to an individual Lymnaea (Galba) cubensis/viator, which if not a trash snail exactly, let me simply say that whole government agencies have been charged to eradicate.  Thirteen pounds of packing material for an empty shell that could not weigh more than 80 mg.

Lymnaea (Galba) cubensis/viator

 

And where is my GDMF locality data?!?? Vainly I pawed through 13 pounds of dripping debris on my wife’s dining room table for any collection information – where was this specimen collected, when and by whom?  All I found was elaborate chain-of-custody paperwork marked simply “Nevada.”

 

I suppose, in retrospect, I should have laughed.  But in fact, I lost my temper entirely.  I was overwhelmed by the absurdity of the situation in the World which I call home.  Having never had a phone number for N-C, I went to my desktop computer to fire off an email, acknowledging receipt.  And I characterized her packing job as “stupid, just plain stupid,” which (I now realize) was over the top.  I continued that I had “no idea whose money she was wasting,” but that I would “no longer be a part of it.”  And I concluded [9], “Here’s the identification of your crappy little shell (Lymnaea cubensis/viator).  But you can keep your crappy $25!”

 

Looking back on that email, with over a year to cool down now, I owe an apology to Ms. Nickle-Chaser.  She was just trying to run a business, and her subcontractor went nuts on her.  The contracts I signed simply said “snails,” and in the world of business, a snail is a snail, even if it’s just a shell.  I feel sure that N-C had adequately budgeted for the elaborate shipping of that empty shell in whatever contract she had signed with whatever strip mall developer or strip mine digger had engaged her services, and that a couple hundred bucks meant nothing to her, much less to them.  I was butting in on a business decision made by Ms. N-C, just as I butt in on that artistic decision made by Ms. Julia Galloway last month.

The world of business and commerce is not compatible with the world of science or the worldview of public policy.  There is no relationship between playing baseball, playing banjo, and playing Hamlet.  But those worldviews are not incompatible either.  Just very simply, and very profoundly different. 

 

I speak the language of science fluently; I can speak a dialect of pidgin-policy; I am profoundly deaf to business. And so, I apologize to Ms. Nickle-Chaser.  But I cannot promise her it won’t happen again, if she ever attempts to reconnect with me, which she has not.

 

Notes

 

[1] For figures of the shell and penial morphology of Pyrgulopsis gibba, together with a brief review of the systematics and evolution of western Pyrgulopsis in general, see:

• Just 125 species of Pyrgulopsis in the American West [7Sept22]

[2] I did not bill for the clean beetle/pebble sample.  But did bill $25 for the snailless bulk sample I had to pick.

 

[3] Lymnaea humilis (8 sites), L. bulimoides (4), Physa acuta (4), L elodes (2), L stagnalis (1), Aplexa elongata (1).

 

[4] In 2021 I was still identifying bulimoides (erroneously) as a subspecies (“techella”) of Lymnaea (Galba) cubensis.  For a review of my laborious untangling of the confusion between bulimoides and cubensis/viator, see:

• What is Lymnaea bulimoides? [13Feb24]
• Oregon, bulimoides, or bust [13Feb25]
• The phantom lymnaeid of the Pacific Northwest [11Mar25]
• Lymnaea (Galba) bulimoides and the NCBI GenDump, with lecture notes on the scientific method [8Apr25]

[5] Well actually, I spent most of my career a sojourner through a third world entirely, that of Education.  And left little mark in that strange land

[6] This is a difficult work to cite.  J. B. Burch's North American Freshwater Snails was published in three different ways.  It was initially commissioned as an identification manual by the US EPA and published by that agency in 1982.  It was also serially published in the journal Walkerana (1980, 1982, 1988) and finally as a stand-alone volume in 1989 (Malacological Publications, Hamburg, MI).

[7] Hershler, R. (1994) A review of the North American freshwater snail genus Pyrgulopsis (Hydrobiidae).  Smithsonian Contributions to Zoology 554: 1 - 115.

 

[8] For more about the career of Dr. Robert Hershler, and his model of the evolutionary relationships among populations of the hydrobiid genus Pyrgulopsis, see:

• My Buddy, Bob [6July22]
• Just 125 species of Pyrgulopsis in the American West [7Sept22]

[9] But added as a PS, “Thanks for the cooler.”

Potamopyrgus, water hardness, and the Gatorade hypothesis

Volume 28(1) of Freshwater Mollusk Biology and Conservation hit the newsstands a couple weeks ago with the unwelcome news that populations of the invasive New Zealand mudsnail, Potamopyrgus antipodarum, have been discovered in two small tributaries of the Monongahela River in Allegheny County, Pennsylvania [1].  These are the first records of Potamopyrgus in the Ohio drainage.

For as many seasons as I have been watching Invasive Species Baseball from the grandstands, the Commonwealth of Pennsylvania has been a perennial contender for the MVA (Most Vigilant Agency) award.  The Pennsylvania Natural Heritage Program iMapInvasives web-based system is peerless, or almost so [2], anywhere in The East.  And in addition to maintaining the state’s elaborate citizen-friendly tool for online reporting, Ms. Amy Jewitt and her iMapInvasives staff post email alerts, publish a newsletter and a blog, sponsor workshops and webinars, and recently even produced a 44-minute, documentary-style film.

Rarely does a month go by that I don’t hear from Amy.  And I’ve also developed longstanding correspondence relationships with Steven Means of the PADEP and Sean Hartzell of the Pennsylvania Fish and Boat Commission (PFBC), who anchors the scientific side of the enterprise [3]. And more often than not, the subject line of all this correspondence with all these colleagues features the abbreviation “NZMS,” New Zealand mudsnail.

Peters Creek, Allegheny Co, PA

So, when one of my clerks dumped the morning mailbag onto the sorting table in my office back on June 26, 2023, I was not surprised to find a cordial message from my good buddy Sean.  And attached to his message was the usual quota of jpeg images of Potamopyrgus, including the one reproduced above.

But although the news that Sean relayed in his 26June23 message was not surprising, I don’t suppose, it was anything but routine.  Three days previous, a PFBC colleague, Mr. Mike Depew, had collected the gastropod sample depicted on those jpegs from a pair of small direct tributaries of the Monongahela River just upstream from Pittsburgh – Peters Creek and Turtle Creek.  Rats.  The first records of Potamopyrgus in an interior drainage of the Eastern United States [4].

My loyal readership will be quite familiar with Potamopyrgus from many previous posts on this blog; occasional visitors are invited to hit the “Invasive species” label at right for a review.  The first Atlantic drainage NZMS population was reported in a mid-Pennsylvania tributary of the Susquehanna River back in 2013 [19Nov13], with reports from Maryland [13June18] and New Jersey [9July18] following rapidly.

In their newly-published note [1], Sean, Mike, and three additional PFBC colleagues have done an excellent job reviewing the ten-year history of this recent Eastern U.S. range expansion, contributing a very nice map of the current distribution of Potamopyrgus across The Keystone State.  Quoting the authors, “both Peters Creek and Turtle Creek contain sections managed as stocked trout fisheries with public fishing access.”  They suggest that this most recent range expansion likely comes “via angling gear from previously invaded sites.”  We concur.

But returning to June of 2023.  In his original message to me, Sean called my attention to the pitting on the shells of the little snails in his jpegs (clearly visible in the figure at the top of this essay), which he “hadn’t seen in Potamopyrgus antipodarum before.”  I agreed that such pitting is unusual, and we swapped a couple additional emails on the topic.  Quoting myself:

The short answer to your question about shell pitting would be, “soft water.”  Presumably Peter’s Creek and Turtle Creek have lower concentrations of calcium, right?  So anywhere the outer proteinaceous periostracum of the shell gets nicked a little bit, the calcium carbonate core of the shell is exposed to dissolution, forming a pit.

That said.  If you’d like to re-write the paragraph above, and scratch out “soft water,” and substitute “Low pH” or “low alkalinity” or “low carbonate” or “Low buffering capacity” or maybe even overall “low conductivity,” it would all be just as true [5].

My 26June23 hypothesis, however, turned out to be unsupportable.  Even as I was offering it, Sean and his PADEP colleague Matthew Shank were embarking on an extensive, statewide study on the relationship between water chemistry and Potamopyrgus invasion that would find the hardness of Peters and Turtle Creeks perfectly suitable.

The Hartzell & Shank paper, published online "early view" last fall and February in hard copy [6], correlated NZMS presence/absence at 443 sites in Pennsylvania to 57 water chemical parameters, including (of course) all those hardness-related variables I had suggested in 2023.  They plotted their 71 present observations (red) and 372 absent observations (blue) on the simplified geological map of Pennsylvania reproduced below.  The relationship between successful Potamopyrgus invasion and the presence of limestone and dolomite in the drainage is striking, am I right?

From Hartzell & Shank [6]

And indeed, the Hartzell & Shank map does show a pair of red “present” dots in the west corresponding to Peters Creek and Turtle Creek [7], indicating limestone in their drainages as well.  Quoting Sean from our more recent (14Apr25) correspondence:

“Although the area has been (mostly historically) impacted by mining, the pH and conductivity samples we had on file for those streams were not reflective of soft water. Additionally, the statewide water chemistry suitability analyses that my colleague Matthew Shank and I worked on more recently . . . suggests that the two respective HUC12s that the snails were found in contain various highly suitable chemical parameters for this species.”

So what, then, might have been the cause of the shell pitting in the original 2023 samples of Potamopyrgus from Peters and Turtle Creeks?  Again, quoting my good buddy Sean, from our 14Apr25 correspondence:

“When Mike (Depew) sampled these streams (both on the same date) and upon finding the P. antipodarum, he realized he neglected to pack any containers to bring snails back to the lab and so upon improvising, he placed them in half-empty Gatorade bottles that he had on hand. As a result, the snails were submerged in Gatorade for about 24 hours before they were transferred to distilled water. From my understanding, Gatorade is quite acidic (a quick Google search indicates a pH of 2.9 to 3.6 depending on the exact flavor purchased) and so this is likely the cause of the pitting observed in the snails.”

Flavor not being among the 57 parameters analyzed by Hartzell & Shank, however, I fear that we shall never have a conclusive answer to this particular mystery.

 

Notes

 

[1] Hartzell, S.M., M.A. Depew, D. Byington, L. Hartman, and R. Pletcher (2025) Collections of the invasive New Zealand mudsnail, Potamopyrgus antipodarum (J.E. Gray, 1843) in the Ohio River basin.  Freshwater Mollusk Biology and Conservation 28: 22 – 25.

[2] To be fair, both New York and Maine also participate in NatureServe's iMapInvasives Network.  But I don't know any of those dedicated folks way up there.  

 

[3] Recent publications from our good friend Sean:

• Hartzell, S.M. and N. Macelko. 2022. Range expansion of the invasive New Zealand Mudsnail (Potamopyrgus antipodarum) in the Susquehanna and Delaware River Basins of Pennsylvania.  Journal of the Pennsylvania Academy of Science 96: 36 - 45.
• Hartzell, S.M. and J.R. Frederick. 2023. First records of the invasive New Zealand mudsnail (Potamopyrgus antipodarum) in the Potomac River Basin.  Northeastern Naturalist 30 (1): N13 - N16.

[4] The USGS Nonindigenous Aquatic Species database does show quite a few records in Wisconsin tributaries of the Rock River, which I think of as being midwestern.

 

[5] I reviewed the subject of environmental calcium as a factor in freshwater gastropod distribution at great length in Chapter 8 of my book, pp 326 - 338:

• Dillon, R.T., Jr. (2000) The Ecology of Freshwater Molluscs.  Cambridge University Press.  509 pp.

[6] Hartzell, S.M. and M.K. Shank. 2025.  Chemical variables predicting colonization risk of the invasive New Zealand mudsnail (Potamopyrgus antipodarum) in Pennsylvania's flowing waters.  Hydrobiologia 852: 645 - 658. https://doi.org/10.1007/s10750-024-05711-2.

 

[7] At the earlier date of the publication of their water quality paper, Hartzell & Shank listed their observations of Potamopyrgus in drainages of The Ohio as “Hartzell et al. unpublished data.”

Three New Fontigens From Virginia

Editor's Note - This essay was previously published as: Dillon, R. T., Jr. (2023b) Three new Fontigens from Virginia.  pp 225 - 232 in The Freshwater Gastropods of North America Volume 6, Yankees at The Gap, and Other Essays.  FWGNA Project, Charleston, SC.

The most faithful and attentive subset of my readership might perhaps remember an essay I posted a year ago this past August [9Aug22], wherein I reviewed the four-year journey that ultimately led to the confirmation of a Fontigens cryptica population inhabiting interstitial spaces in the karstland of central Kentucky [1].  Here is a detail that I cannot imagine any of you could possibly remember, no matter how attentive you have been.  About halfway through that essay I mentioned that two of the Fontigens samples Hsiu-Ping Liu sequenced for our big mtDNA gene tree were contributed by “our good friends Wil Orndorff and Tom Malabad of the VaDCR."

Lane Cave (F. hershleri)

Now let me highlight a blessing of the sort I have found gratifyingly common throughout my 40-year professional career, of which I should be more thankful, but which I fear I have often taken for granted.  Completely independent of the Fontigens cryptica research project that Lori Schroeder and I kept on a slow burner in Kentucky from 2017 – 2021, in November of 2018 I received a cordial email from my old friend Wil Orndorff [2], with the subject line “Some Virginia cave and spring snail collections that need you.”  And after a bit of negotiation, a big box containing 61 tiny plastic vials arrived with a thump on my front porch.  The even-tinier gastropod samples enclosed in those 61 tiny vials had been collected by VaDCR Natural Heritage from caves and cave springs all over the Old Dominion, 1998 – 2018.  Holy crap, I replied to Wil.  N=61 is not “some.”

A bit daunted, perhaps, but undeterred, I went to work sorting and identifying Wil’s very large sample of very tiny snails, a process that stretched four months, into March of 2019.  Of the 61 samples, 30 contained only land snails, and 11 contained only freshwater gastropods typical of above-ground habitats: pleurocerids, physids, and so forth.  That left a (still remarkable) 20 samples of hydrobioid cave snails on my lab bench.

Of all 7,999,999,999 people alive in this world today who have not pulled a fire alarm at the Academy of Natural Sciences of Philadelphia in the middle of the night [3], I flatter myself that I have developed the keenest eye for Fontigens.  Those 20 samples included 11 of F. orolibas, 3 of F. bottimeri, 2 of F. morrisoni, 2 Holsingeria, and 2 samples of hydrobioid cave snails unlike any I had ever seen before.

From the Sugar Run Cave System of Giles County, Virginia, (draining west into the New -> Ohio) I found a single sample of 14 individual Fontigens bearing strikingly ovoid shells – much more convex in their outline than any I had ever seen, bearing a depressed apex.  And from Lane Cave in Scott County, Virginia, (draining south into the Clinch -> Tennessee) I found a singleton hydrobioid snail that looked more like an Amnicola or a Lyogyrus than a Fontigens.  I left those two lots unidentified in the spreadsheet I sent to Wil on 1Mar19.  And here is how I closed my email: “After I die, if I’m reincarnated [4] as the second Bob Hershler, I’ll take another look at these.  Not before.”

So two months later, Lori Schroeder and Andrew Berry discovered one single putative F. cryptica living under a rock at a springhead in the Bernheim Forest of central Kentucky [3July2019].  And fight it though I most certainly had for years, I found myself in the Fontigens business.  I contacted Hsiu-Ping Liu out in Denver and prevailed over her to join Lori, Andrew and me in a grant proposal, then set out on that Fontigens-themed tour of the Great Valley of Virginia I described in my essay of last August [9Aug22], upon my return promptly posting my large sample of tiny snails off to Hsiu-Ping for sequencing.

And included among all those control samples of F. nickliniana and F. orolibas and F. morrisoni and F. bottimeri were, quoting now from my email to Hsiu-Ping of 17July19 …

…two extra samples at the bottom of my spreadsheet, labelled “xtr1” and “xtr2.”  I think I told you that Wil Orndorff and our colleagues at the Va-DCR sent me a big shipment of cave snails last fall, from all over Virginia.  Included in that shipment were two samples I absolutely could not identify, one from Sugar Run Cave in Giles County, the other from Lane Cave in Scott County.  Obviously, these are very low priority.  But if, in the (increasingly unlikely) event we had a bit of money left over… my colleagues and I would be most gratified.

The first results came back from Hsiu-Ping in late August of 2019 – an early version of that gene tree I shared with you all on [9Aug22].  And we were immediately impressed by the tremendous interpopulation CO1 sequence divergence within our control species which, you will recall, ended up being the headline of the paper we ultimately published in 2021 [1].  But the intraspecific variance did not swamp out the sequence variation among species, which ranged from a bit less than 9% up to a bit more than 20%.  And the mean sequence divergence between three snails sampled from the Sugar Run Cave System and their nearest genetic neighbor (F. morrisoni) was 9.0%, and that between our singleton from Lane Cave and its nearest neighbor (one of the F. nickliniana populations) was 13.2%, strongly supporting the specific status of both those “xtr” populations.

Sugar Run Cave (F. benfieldi)

Again, I must emphasize.  I would never dream of looking for new species on a gene tree.  But I brought a hypothesis with me to the analysis that Hsiu-Ping so ably executed in August of 2019, arising from my understanding of the biology of the organisms I was studying.  I predicted that the Lane Cave and Sugar Run populations might represent heretofore undiscovered species of Fontigens.  And testing that hypothesis with a gene tree, I found that it was supported.

And so, I surrendered to the inevitability that I myself would be duty-bound to describe a couple new species of Fontigens in this life, rather than the next.  So, on 29Aug19 I wrote to Wil & Tom:

“Do you have any plans to return to either Lane Cave or Sugar Run Cave any time soon?  We really need more snails.  If you could find a decent sample size (I would love N = 30) I myself would be game to dissect them and describe them formally.  I’m not Bob Hershler, so need a bunch of extras, so I can screw up.  Species descriptions are not my forte, but it needs to be done, and I don’t know anybody else who could do it.”

The answer turned out to be an enthusiastic yes.  It materialized that over the previous nine months, Wil and Tom had continued to stomp all over the Commonwealth, lowering themselves upside down into every hole large enough to lose a basketball, scouring the inner recesses of the Old Dominion for Fontigens.  Although they had not revisited either Lane Cave or the Sugar Run Cave System by that point, they had already collected 12 fresh samples, which they were pleased to send me in September of 2019.  And in February of 2020, yet another fresh batch of 10 Fontigens samples arrived on my doorstep, this one including N = 3 from Lane Cave, N = 18 from the Sugar Run Cave System, and N = 39 from a new sampling location, Dulaney’s Cave, which turned out to be the most interesting of all.

At this point, a boxed essay on the environments from which these populations were sampled might be helpful.  Lane Cave is developed in Cambrian Marysville Limestone atop a bluff running parallel to Copper Creek of the Clinch River drainage, a tributary of the Tennessee.  The cave is a not-insubstantial 0.8 km long and about 60 m deep.  The stream running through it seems to be fed by multiple, small surface sinks at the top of the bluff, and apparently resurges at a spring tributary to Copper Creek.

The Sugar Run Cave system, 170 km northeast, is much larger and more complicated. Developed 200 m deep in Ordovician limestone on the northeast flank of Sugar Run Mountain, the system includes at least 45 km of passages, multiple streams and multiple entrances, the relationships among which are poorly understood.  The sample that Tom & Wil sent me in February labeled “Dulaneys Cave” came from waters connected to subterranean Sugar Run through some unknown passage, all of which ultimately drains into Walker Creek of the New (-> Ohio) River system.

Dulaney's Cave, elongate (F. davisi)

And when I dumped that little plastic vial labeled “Dulaneys” into a dish under my dissecting scope, my eyes were met by quite the unexpected sight.

Yes, I counted N = 31 of those strange Fontigens bearing the unique ovoid shells I had previously seen in the Sugar Run samples.  But plopped right in the middle of those 31 were N = 8 individuals of what looked like yet another species of Fontigens – a third one – I had never seen before.  These bore shells that were larger, and darker, and elongate/pupoid in overall outline.  Good grief!

So I started my dissections.  And of course, after each dissection I saved all the tissues for sequencing.  And in March of 2020 I pitched Hsiu-Ping on the possibility of a second project, beyond the Fontigens cryptica project to which we were already obligated, describing three new Fontigens species from Virginia.

Well, by that point pretty much all the college campuses nationwide were in the grip of the Coronavirus panic.  But Hsiu-Ping, bless her heart, moved her lab into the basement of her private home, and with perhaps even less distraction than she might have otherwise suffered in an ordinary spring semester, was happy to collaborate. 

And in so in May of 2020 I sent Hsiu-Ping two fresh samples of the Lane Cave unknown, three from Sugar Run, and three from Dulaney Cave.  I told her that the Dulaney sample looked like two different shell phenotypes to me, elongate and ovoid, although I didn’t tell her which tubes held which phenotype.  And by that point I was aware of the anatomical similarity between the Dulaney/Sugar Run snails and Fontigens orolibas.  So I also sent her a fresh control sample of F. orolibas from nearby Tawney’s Cave [5] as well.

Baysian Tree abbreviated from [6]

The CO1 gene tree above is an abridged version of the tree Hsiu-Ping sent me in March of 2021, showing just one individual per population.  The full-featured model, which you can see in the Appendix of Volume 5 [6], was based on N = 47 individual Fontigens, including 3 individuals from Lane Cave, 6 from Sugar Run, 2 Dulaneys-elongate, 1 Dulaneys-ovoid, and 2 from the control orolibas at Tawney’s Cave.  Most of the data (shown in black) were borrowed from the F. cryptica study of Liu et al [1] published in 2021.  The sequences in blue are new.

Marked in red are the minimum sequence divergences between each of our three putatively new species and its nearest neighbor, all greater than the minimum intraspecific distance we set in our 2021 paper.

The bottom line was just published last month as an appendix to FWGNA Volume 5, by Dillon, Malabad, Orndorff and Liu [6].  The two new Fontigens species from the Sugar Run / Dulaney system are both members of the orolibas group, bearing a tripartite penis with one tubular and one bulbous accessory gland.  The bodies and eyespots of both species are unpigmented.  I was pleased to name the population bearing ovoid shells for Dr. Ernest F. (Fred) Benfield, my undergraduate mentor at Virginia Tech [7], and the population bearing elongate shells for Dr. George M. Davis, my graduate mentor at the ANSP [8].

The Lane Cave Fontigens is a member of the nickliniana group, its tripartite penis bearing two tubular glands.  Its body and eye spots are pigmented.  These observations, together with the fact that our collections arrived in a mixture with juvenile above-ground-dwelling Pleurocera simplex (Say), suggest to us that the Lane Cave Fontigens might be capable of living in surface waters.  This new species I was gratified to name in honor of my buddy, Bob [3].

 

Notes:

[1] Liu, H-P., L. Schroeder, A. Berry, and R.T. Dillon, Jr. (2021) High levels of mitochondrial DNA sequence divergence among isolated populations of Fontigens (Truncatelloidea: Emmericiidae) in eastern USA. Journal of Molluscan Studies 87. [pdf] [html]

[2] You might remember Wil as the leader of that expedition I undertook into Unthanks Cave way back in 2007, as described in:

• Cave Snail Adventure [12Aug07]

[3] For a review of the professional contributions of Dr. Robert Hershler, together with a well-curated anecdote or two more personal in their nature, see:

• My Buddy Bob [6July22]

[4] To be very clear, I am a Presbyterian.  If I find myself reincarnated as anything – be it cow, bug, malacologist or Methodist – I shall be most disappointed.

[5] Two of our previous [1] orolibas populations (including the topotypes) came from Atlantic drainages, and the third was from a Tennessee drainage.  So since the Sugar Run Cave system drains toward the New River, we felt as though a fourth orolibas control (Tawney’s Cave) was necessary.

[6] 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. [pdf]  Order your copies today!

• FWGNA Volumes 5, 6, and 7 Now Available! [6Dec23]

[7] Fred Benfield made cameo appearances in my essay of 6Apr23 (Growing Up With Periwinkles) and in my essay of [6May14], (To Identify a Physa, 1975).  Look at footnote #16 of the 2014 essay for a sample of Fred's memorable advice.

[8] George Davis costarred with Steve Ahlstedt in my essay of 5Apr22 (The Ham, the Cheese, and Lithasia jayana) and made cameo appearances in [28Mar22], [11Mar19], and [16July10].