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].