Dr. Rob Dillon, Coordinator

Wednesday, July 3, 2019

Finding Fontigens cryptica

Faithful readers of this blog may remember a series of essays I posted back in 2017 about Lori Schroeder’s tiny snail, the obscure hydrobiid Fontigens cryptica [1].  The species was described in 1963 by Hubricht [2] from a spring in southern Indiana about the size of a man’s fist, and has not been seen at its type locality since, despite repeated efforts to recollect it.  The only subsequent live collections have been made by J. J. (Jerry) Lewis, extracted from subterranean stream gravels at a couple widely-scattered sites in Indiana.  Our buddy Jerry has suggested that F. cryptica may be obligately adapted to the interstitial spaces of aquifers.

Lori Schroeder's tiny snail
So back in 2008 Mrs. Lori Schroeder, a talented amateur malacologist living in central Kentucky, enlisted in a Bioblitz one-year survey of the land snail fauna of the nearby Bernheim Arboretum and Research Forest.  And in addition to her land snails, in 2013 she began to run across scattered, rare hydrobiid shells in dry forest litter sampled alongside several small Bernheim streams, which she and I were ultimately able to identify as those of Fontigens cryptica.  But despite long term, persistent, and heroic efforts on her part she had not, as of 2017, been able to discover a single living individual.  As I brought my series of essays to a close, I mentioned something about Lori’s plans for a Bou-Rouch groundwater sampler and promised to keep you all posted.

A Bou-Rouch sampler is basically a hand-powered piston pump with a short intake, modified to be driven into the ground [3].  Lori and her husband Jeff did all manner of impressive research on soil types, subterranean gravels and impervious layers in the Bernheim area, purchased the necessary hardware, assembled the machine, and by the 2018 season were hard at work pumping groundwater through lady’s trouser socks ($1.00/2pk from Dollar General).  They extended their search into neighboring, privately-held tracts, exploring new springs, old wells, and small caves.  And finished the 2018 field season in failure.  Lori did not give up hope, but she did need some sort of new idea.

Meanwhile her land snail survey continued.  And a couple months ago I got an excited email from her, reporting the discovery of another dry Fontigens shell in a previously unexplored valley recently added to the Bernheim management portfolio – the Cedar Grove Tract, about 15 km north of the Harrison and Wilson Creek areas where she had been concentrating her efforts.  And the Cedar Creek drainage boasts a spring that Lori characterized as “super nice” with “ice cold crystal clear water.” 
The super-nice spring
So, on Friday morning, 24May19, a Corps of Discovery comprised of Lori, Jeff, and Bernheim Director of Conservation Mr. Andrew Berry launched an expedition to the upper regions of the Cedar Grove Tract.  This was my benediction, verbatim: “find a decent-sized rock, or rocks, DIRECTLY at the spring head.  Right where the water comes out of the ground.  Pick up that rock and look attached UNDERNEATH it.  That’s where your Fontigens will be.”

And their efforts were crowned with success!  The photo above shows a rock ledge running to the right of the super-nice spring, as the photographer is standing in the spring run.  Under that ledge was a decent-sized rock, and attached to the underside of that decent-sized rock was one, single Fontigens cryptica.  The snail was translucent, whitish, and blind, as originally described by Hubricht in 1963.  Next time bring forceps.

The genus Fontigens is among the poorest-known of the North American hydrobioid gastropods.  They share their strange, multiply-lobed penial morphology only with the Old World genus Emmericia, which prompted Morrison [4] to assign the genus to the subfamily Emmericiinae in the old Hydrobiidae (s.l.), a judgement subsequently endorsed by Hershler [5].  Dwight Taylor [6] disagreed, proposing a new subfamily Fontigentinae to contain them, a judgement endorsed by Burch [7].  The new classification system recently proposed by Wilke and colleagues [8] split out a separate Emmericiidae while retaining Fontigens in the Hydrobiidae (s.s.) on the basis of DNA sequence data from a single individual Fontigens nickliniana sampled from Michigan in 2012.  To this day, the CO1 and 18S sequences from that single F. nickliniana remain the only Fontigens data deposited in GenBank. 
From left: Andrew Berry, Fontigens cryptica, Lori Schroeder
Clearly the genetics of one single little white snail found under a rock at a springhead in central Kentucky cannot be studied in isolation.  The significance of Lori Schroeder’s tiny snail can only be understood contextualized by at least a rudimentary understanding of the evolution of the North American Fontigens as a group.

So, I called our colleague Hsiu-Ping Liu at the University of Denver.  And it materialized that she was very much interested in the evolution of Fontigens, and that Bob Hershler had sent her a not-insubstantial collection of samples prior to his retirement last year.  And I myself am currently holding a nice collection of cave snail samples that our good friend Wil Orndorff sent me last year from the long term VA-DCR biotic survey of Virginia caves [9].  And together Hsiu-Ping and I worked up a small proposal to the Bernheim Board for a study on the evolution of Fontigens across the eastern USA.

Meanwhile Lori and Andrew have mounted several additional field trips to the Cedar Creek Spring and failed to find any additional snails.  We’ll keep you posted on progress along both fronts.

Let me leave you this month with three teasers, and a reading assignment:
  • If you were a state consultant looking for a broad strip of open land to connect Interstate 65 and Interstate 71 around greater metropolitan Louisville, where might you find it?
  • If you were a planner with Louisville Gas & Electric, looking for an open corridor through which to run a natural gas pipeline, where might you run it?
  • How much noise can one tiny white snail make?
Now study this press release:
  • New rare snail discovered on proposed pipeline, interstate connector routes [html] [pdf]
To be continued!


[1] These three essays were published earlier this year on pp 235 - 250 of my new book, The Freshwater Gastropods of North America, Volume III: Essays on the Prosobranchs [html].  To refresh your memory:
  • Lori Schroeder’s Tiny Snails [17July17]
  • The Most Cryptic Freshwater Gastropod in The World [6Aug17]
  • Not Finding Fontigens cryptica [6Sept17]
[2] Hubricht, L. (1963)  New species of Hydrobiidae.  Nautilus 76: 138 - 140.

[3] More about the Bou-Rouch method is available at the website of the Hypogean Crustacea Recording Scheme [html]

[4]  Morrison, J. P. E. (1949)  The Cave Snails of Eastern North America (abstract).  The American Malacological Union Bulletin 15: 13 – 15.

[5] 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.

[6] Taylor, D. W. (1966)  A remarkable snail fauna from Coahuila, Mexico.  Veliger 9: 152-228.

[7]  Burch originally proposed his classification for the North American freshwater gastropods in 1978 (Journal de Conchyliologie 115: 1-9). His "North American Freshwater Snails" was published as an EPA manual in 1982, as three volumes of Walkerana (1980, 1982, 1988), and as a stand-alone book in 1989.

[8] Wilke T., Haase M., Hershler R., Liu H-P., Misof B., Ponder W. (2013)  Pushing short DNA fragments to the limit: Phylogenetic relationships of “hydrobioid” gastropods (Caenogastropoda: Rissooidea).  Molecular Phylogenetics and Evolution 66: 715 – 736.  For a review, see:
  • The Classification of the Hydrobioids [18Aug16]
[9] We first met Wil Orndorff in my essay about an expedition for Holsingeria unthanksensis in southwest Virginia.  See pp 217 - 222 in The Freshwater Gastropods of North America, Volume III: Essays on the Prosobranchs [html].  Or:

Wednesday, June 19, 2019

The Freshwater Gastropods of The Ohio!

We are excited to announce the grand opening of a major new web resource, The Freshwater Gastropods of The Ohio, by Martin Kohl, Ryan Evans, Mark Pyron, Tom Watters, Kevin Cummings, Will Reeves, Jeff Bailey, Mike Whitman, and myself.  Check it out:

Here we report the results of a comprehensive freshwater gastropod survey conducted over all waters draining into the Ohio River above the mouth of the Tennessee/Cumberland, an area of some 144,000 square miles.  Roughly 37% of the 5,250 records the team gathered were from museums, 35% from natural resource agencies, and 26% from original field collections.  We identified 70 species and subspecies of freshwater gastropods inhabiting this vast study area, providing a dichotomous key, a photo gallery, range maps and ecological notes for each.

With the addition of the Ohio fauna to the faunas of the Atlantic and Tennessee drainages previously documented, the overall coverage of the Freshwater Gastropods of North America web resource has expanded from 89 to 113 species and subspecies, inhabiting all or part of 15 states.  The main FWGNA site now features an updated “Synthesis 3.0” in which every element of this diverse and far-flung fauna is ranked and classified into quartiles by incidence, using the Gaston system we pioneered back in 2013.

The entire site has been spruced up and polished to a fine sheen.  Even the bibliography has been updated, now featuring 268 entries.  Visit us again, for the first time!

Wednesday, May 22, 2019

20 Years of Progress in the Museums

The first FWGNA project was the “digitization” of museum collections.  The year was 1999, and at the dawn of the worldwide web, only two national collections of freshwater gastropods were searchable online: those of the Academy of Natural Sciences of Philadelphia (ANSP) and the Florida State Museum (FLMNH).  So the first NSF proposal a committee of nine of us wrote – Phase I of three projected phases – was to unify the freshwater gastropod holdings of 21 North American museums into a single, online database of approximately 200,000 records.  A Phase II field survey and a Phase III monographic review were set to follow [1].

That proposal was not funded.  But progress in the national museums continued, difficult though it was for me to understand at the time.  I revisited the subject of the online availability of freshwater gastropod collections ten years later, in April of 2009 [2].  And at that point, the number of national or regional mollusk collections searchable online had grown to ten.  To quote myself directly: “I’m impressed!”

Which of those ten might be the most useful for the FWGNA Project?  Research suggests that the world is inhabited by mollusks that are not freshwater snails.  And although Class = Gastropoda is a common search criterion in almost all malacological databases, Habitat or Environment = freshwater is surprisingly rare.  So my first idea was to compare the freshwater gastropod fractions of the ten museums by searching for “Family = Physidae.”  But as of 2009, several important museum databases were not even effectively searchable by family.  So as a crude estimate of the freshwater gastropod holdings of the ten databases available online as of 2009, I executed a simple search for “Campeloma.”

My results, published on this blog 15Apr2009, showed the University of Michigan Museum of Zoology (UMMZ) in the lead at Campeloma = 2,456 records, followed by the FLMNH Campeloma = 1,414, then ANSP = 890, and Harvard’s Museum of Comparative Zoology (MCZ) = 488.

Brand new, as of 2009, was the Global Biodiversity Information Facility (GBIF), hosted at Copenhagen [2].  Many of our colleagues felt as though the GBIF was the wave of the future.  And quite a few prominent North American museums were cooperating, including the USNM, ANSP, and FLMNH.  My query of the GBIF database (executed 26May09) returned Campeloma = 3,210.

So another ten years have passed.  And as impressive as C = 3,210 most certainly is, how does that statistic compare with the online freshwater gastropod records retrievable today?  Spoiler alert!  C = 11,874.

In February of 2010 a workshop was held at the National Evolutionary Synthesis Center in Durham, NC, ultimately yielding “A Strategic Plan for Establishing a Network Integrated Biocollections Alliance” [3].  And shortly thereafter, the NSF began accepting proposals to its new “Advancing Digitization of Biological Collections Program.”  The effect has been remarkable.

Initial projects were “thematic” around the various Kingdoms and Phyla of Biology, rather reminiscent of the chromosomally-based approach pioneered by the Human Genome project.  The “Thematic Collection Network” most directly relevant to our interests here was “Invert-E-Base,” kick-started in 2014 by a consortium that included our colleagues Rudiger Bieler of the Field Museum of Natural History in Chicago (FMNH), Diarmaid O’Foighil of the UMMZ, and Elizabeth Shea of the Delaware Museum of Natural History (DMNH) [4]. Ultimately Invert-E-Base grew to involve 18 US museums, universities and other institutions, including many with substantial freshwater gastropod holdings, such as the Carnegie Museum of Natural History (CMNH), the Illinois Natural History Survey (INHS), and the North Carolina Museum of Natural Sciences (NCSM).

Meanwhile, NSF also funded the “Advancing Digitization of Biodiversity Collections Program” (iDigBio) to serve as a hub for all the data being collected by the various thematic collection networks [5]. Additional contributions rolled in from all the other museums where digitization efforts had been proceeding independently, such as ANSP, USNM, FLMNH, MCZ, and so forth. 

Today the iDigBio database includes 4.3 million gastropod records held by scores of institutions worldwide, including The Canadian Museum, the British Museum, the Australian Museum, all over Europe – everywhere.  My search of the iDigBio database for Genus = Campeloma last week returned that eye-popping 11,874 figure quoted above.  And how about Family = Physidae AND Continent = North America?  Drum roll, please.  The iDigBio database boasts 31,417 records of the North American Physidae.

Here are the top-ten museums, ranked by their North American physid holdings, as I retrieved them through iDigBio last week.  The links are to their local online search facilities, if maintained, which tend to hold more current data. 
  1. UMMZ 5,492
  2. NMNH 5,417
  3. MCZ 3,619
  4. ANSP 3,415
  5. FMNH 2,726
  6. FLMNH 2,083
  7. INHS 1,717
  8. CMNH 1,051 (No local search)
  9. NCSM 824
  10. DMNH 653 (No local search)
Back in 2017 The American Malacological Society sponsored a symposium entitled, “The North American Mollusk Collections – A Status Report,” which subsequently yielded several excellent papers in the American Malacological Bulletin.  Here’s a tidbit I gleaned from the contribution by Sierwald and colleagues [6]:
“Of the 6.2 million cataloged lots (of mollusks), 4.5 million (73%) have undergone some form of data digitization (which includes all forms of digitization, e.g. ledger records entered, transcribed, or imported into word processor, spread sheet, or relational database formats). About 1.1 million (25%) of digitized records have been georeferenced, which represents 18% of all cataloged lots. Only 20 collections (less than 25%) claim to be fully Darwin Core compliant, however, 34 of the 66 collections with some form of digitization are searchable online through iDigBio, Arctos, or other portals, or directly through institutional websites.”
That's great, but there’s certainly still work to be done.  Prominent among those institutions not searchable online at present is the Ohio Museum of Biodiversity (OSUM) in Columbus, which boasts very significant freshwater gastropod holdings.  Our good buddy Tom Watters is gittin’ ‘er done, even as we speak.

I should conclude with a word of warning.  One of the many criticisms leveled at our FWGNA proposal way back in 1999 was simply the question of data quality.  How would we know that all those collections of freshwater snails we were proposing to digitize really were what their museum labels said they were?  Darn good question.

The reason that I have become such an avid customer of online databases over the last 20 years is that I am preparing to visit the actual collections themselves.  I print shopping lists, fasten them to an old-fashioned clipboard, and walk around the actual, physical collections, inspecting every lot personally.  Only after I have personally verified a record is it added to the FWGNA database.  One at a time.

The more powerful a tool, the more dangerous it becomes.  You  can hurt yourself with a saw, you can kill yourself with a chainsaw.  I feel sure that 100% of my readership is acutely aware that a simple Google search is simultaneously very powerful, and very dangerous, and all of us know how to use Google safely.  Exactly the same caveats pertain to the NCBI GenBank, and to the iDigBio database.  Like my Momma used to say, “You be careful with that thing now, you hear?”


[1] For more about the history of the FWGNA Project, see:
[2] My 2009 museum survey was a two-parter.  See:
  • Progress in the Museums [15Apr09]
  • Freshwater Gastropod Databases Go Global! [26May09]
[3] A Strategic Plan for Establishing a Network Integrated Biocollections Alliance:
NIBA Brochure [pdf]

[4] Sort-of obsolete, but nevertheless interesting:
  • Welcome to Invert-E-Base [html]
[5] Integrated Digitized Biocollections:
[6] Sierwald, P. R. Bieler, E.K. Shea and G. Rosenberg (2018) Mobilizing Mollusks: Status Update on Mollusk Collections in the U.S.A. and Canada.  American Malacological Bulletin 36(2):177-214. https://doi.org/10.4003/006.036.020

Friday, April 19, 2019

FWGNA Volumes 1 - 4 Now Available!

Extra, extra [1]!  Read all about it!  We are delighted to announce that the first formal publications of the Freshwater Gastropods of North America Project are now available for purchase from all the usual online outlets, as well from the publisher at a substantial discount.
Buy all four from the author's profile page
Volume 1, by Dillon, Ashton, Reeves, Smith, Stewart and Watson, reports the results of the largest-scale inventory of freshwater snails ever conducted in the United States. We have reviewed and synthesized macrobenthic collections taken by ten natural resource agencies, malacological holdings at eight museums, and our own original collections from hundreds of sites, covering all freshwater gastropod habitat in Atlantic drainage systems from Georgia to the New York line. For each of the 70 species and subspecies we provide:
  • A dichotomous key for identification.
  • Full-color figures.
  • Range maps at county scale.
  • Notes on habitat, ecology, life history, and reproductive biology.
  • Systematic and taxonomic updates to modern standards.
We propose a new, objective system of conservation status ranking [2], and a new species of pleurocerid snail is described in the appendix [3].

Volumes 2, 3, and 4 are collections of essays, originally appearing in the present blog 2003 – 2019, now edited and rearranged thematically.  Volume 2 collects 29 essays on the systematics and evolution of the freshwater pulmonates of North America, Volume 3 comprises 37 essays on the systematics and evolution of the prosobranchs, and Volume 4 collects 38 essays reviewing ecological and biogeographical themes.  These volumes are intended to support and augment the scientific results reported in Volume 1.

The retail prices for the four individual volumes are $39.95, $34.95, $35.45, and $35.45, respectively.  Although not unreasonable for 250-page glossy color paperbacks in this day and age, I don’t mind telling you that the method by which those retail prices were determined irritated me considerably.  The figures were essentially dictated by amazon.com as the lowest possible sticker-price that would yield $1.00 for the FWGNA [4].  All the rest of the sale either goes to my publisher (Bookbaby) or to Amazon for its marketing services.

So then immediately after the volumes hit the market a couple days ago, Amazon began advertising cut-rate prices.  For Volume 1 today, the amazon.com site is listing “10 used from $34.66” and “21 new from $32.61.”  I do not understand this phenomenon at all.

Here’s the bottom line.  I would encourage you all to cut out the online retailing giants, and purchase FWGNA Volumes 1 – 4 directly from the publisher’s website.  The FWGNA Project [5] will receive a substantially larger fraction of the sale. 

And as an inducement, I have arranged with Bookbaby to sell the entire four-volume set for the discount price of $99.95.  That’s a savings of $45.85 to you, and everybody wins, except Jeff Bezos.

Follow this simple three-step process:
  • Go to my Author Profile Page [here].
  • Add all four titles as listed at the bottom of that page to your shopping cart.
  • Apply the coupon code FWGNA4 to each volume.
The system should discount your package price from $145.80 to $99.95.

Perhaps unsurprisingly, each of the four volumes features a fairly extensive acknowledgement section.  But in addition to those lengthy lists of explicit appreciations, I do want to thank the entire readership of the FWGNA Blog for your support and help over the 20-year gestation of this project.  I have received quite a few helpful comments and suggestions from you all over the history of this forum, sometimes by direct email, other times anonymously commented.  I prefer the former, but appreciate have always appreciated all input, regardless of provenance.


[1] No, this is not an “Extra extra.”  As I understand it, an “Extra” was a second run of a daily newspaper, printed to update the readership on some breaking news.  And an “Extra extra” was a third printing.  So, blog posts aren’t printed.  And even if the present text should ultimately appear in print, which is, after all, one of the primary messages being conveyed in the blog post above, it cannot possibly be extra in any sense.  This is the first run of the blog for April of 2019.  I’m sorry, I just like the sound of “Extra, extra.”

[2] For more on the objective system of incidence ranking piloted by the FWGNA project, see:
[3] For more about my newly-described species of pleurocerid snail, see last month’s post:
  • Pleurocera shenandoa n.sp. [11Mar19]
[4] And no, this is not $1.00 profit.  The set-up costs for these books were a couple thousand dollars each.  There is no way that the FWGNA will ever make any actual profit [5], but profit has never been the point.

[5] And perhaps you remember, the FWGNA Project is a sole proprietorship of Rob Dillon.  So I admit that the distinction between the FWGNA and Rob Dillon is a fine one.  But important.  For more, see:

Monday, March 11, 2019

Pleurocera shenandoa n.sp.

Editor’s Note – This essay was subsequently published as: Dillon, R.T., Jr. (2019c) Pleurocera shenandoa n.sp.  Pp 101 - 108 in The Freshwater Gastropods of North America Volume 3, Essays on the Prosobranchs.  FWGNA Press, Charleston.

One of the recurring subthemes we have developed in this blog, over its 20 year history, has been the roll of serendipity in science.  The study of Pleurocera clavaeformis described in our posts of February 2007 and March 2011 [1] and the study of P. semicarinata reported in our post of July 2014 [2] were both designed to confirm cryptic phenotypic plasticity in populations of pleurocerid snails using genetic variance at allozyme-encoding loci.  The sets of populations involved in both of those studies were geographically widespread, which meant that I needed to sample some additional sets of well-characterized pleurocerid populations as controls to calibrate the expected levels of genetic divergence among my sets of experimental populations.

An element of serendipity was introduced into both studies when the genetics of the “well-characterized” control populations turned out to be as surprising as the experimental populations.  The additional research this necessitated, for P. simplex (reported in Sept – Nov 2016) [3] and P. canaliculata (reported in June 2013) [4] yielded additional insights into the evolutionary biology of an enigmatic group of organisms that becomes more fascinating to me every time I step in the creek.

So, there were actually two sorts of controls for the studies referenced above, calibration standards and mobility standards.  In the very first study of allozyme polymorphism I ever published [5], way back in 1980, I set Pleurocera simplex population WYTH as a mobility standard, defining the mobility of the most common allozyme band in that population as 100 SDEMM (standard Dillon electrophoretic mobility millimeters.)  And in every study of allozyme polymorphism in pleurocerid populations I have published since that date, a total of 13 in all, I have included a population linked somehow to my 1980 population WYTH, calibrating every allele at every locus by its mobility relative to that standard.
Figure 4 of Dillon [2]
So in both my 2013 study of cryptic phenotypic plasticity in Pleurocera canaliculata [4], and in my related 2014 study of P. semicarinata [2], my mobility standard was population SV.  This was the same population of P. semicarinata I called “PINE” in my 1980 paper, which I ran beside population WYTH thirty-five years previous, hence calibrating the mobilities of all allozyme bands in the 2013 and 2014 papers in units of SDEMM.

Now look at Figure 4 of my 2014 study, reproduced above.  “Standard” Virginia semicarinata population SV is more genetically similar to P. canaliculata than to any member of the (nominally conspecific) semicarinata/livescens/obovata cluster.  In fact, my P. semicarinata “standard” seems to be the most genetically divergent population in the entire study!

What is this semicarinata population from Virginia I called SV in 2014, which I called PINE in 1980?  And what made me think that it was Pleurocera semicarinata in the first place?

Let’s flip the calendar back another five years to 1975, when the young Rob Dillon was a sophomore at Virginia Tech, blissfully bumping around on the backroads of the upper New River drainage with boots, nets and buckets thrown in the back of a state pickup truck.  You may recall, from my essay of May 2014 [6], that my undergraduate research thesis was entitled “Factors in the distributional ecology of upper New River mollusks (Va/NC).”

Goodrich’s papers [7,8] were available in the university library in 1975, but this was before the publication of Burch’s EPA key [9], so I had no pictures.  Nor (of course) any access to reference collections.  So, I confess that I simply guessed.  Goodrich listed just two species of Goniobasis from the area, Goniobasis proxima as a trans-Appalachian inhabitant of the highlands of North Carolina and G. simplex in the Bluestone River of West Virginia, apparently captured over from the Tennessee drainage.  That suggested to me that my softwater species in the New River must be G. proxima, and my hardwater species must be G. simplex.

Even a college sophomore knew crappy science when he saw it, and he was not happy about that, at all.  I do remember thinking, 45 years ago, that there seemed to be at least TWO hardwater species of Goniobasis in the upper New River drainage in addition to the single softwater species but had no idea how to start solving the problem.

A method to start solving the problem presented itself in grad school at the University of Pennsylvania.  My advisor at the ANSP, Dr. George Davis, had a big grant to work out the systematics of unionid mussels with the brand-new technique of allozyme electrophoresis, and was generous enough to allow me to bring my samples of pleurocerids into his lab.  And absorbed onto the little paper wicks applied onto the butt ends of the first gels I ever ran was the proteinaceous goo of ground-up Goniobasis from the upper New River drainage.

Our gels clearly showed one species in the softwater and two species in the hard [5].  And by now I did have a research collection at my fingertips.  The softwater species was (indeed) Goniobasis proxima, upon which I focused my dissertation, and most of the rest of my career, and one of the two hardwater species was (indeed) Goniobasis simplex.  That other hardwater species seemed to match Goniobasis semicarinata.
Figure 2 of Dillon & Davis [5]
Of course, this was just shell-matching.  That is all that pleurocerid taxonomy had ever been, as of 1980.  And Goodrich [7] gave the range of Goniobasis semicarinata as “Tributaries of Ohio River, Scioto River to Big Blue River, Indiana; Licking River to Salt River in Kentucky,” saying nothing about Virginia at all.  I assumed at the time, and continued to assume for many years, that the range of G. semicarinata must extend from Ohio through West Virginia up some 200 km of Kanawha River drainage into the upper New River basin, unbeknownst to Goodrich.

The 1980 paper I published with George Davis ultimately involved two populations of G. simplex, six populations of G. proxima, and the four populations we identified as “Goniobasis semicarinata,” shown on the bottom row of our Figure 2 as reproduced above.  Image (k) depicts population “PINE” from Little Pine Run, a tributary of the New River in Pulaski County, which (renamed “SV”) was ultimately to serve as a mobility standard for my 2013 & 2014 studies of cryptic phenotypic plasticity in canaliculata [4] and semicarinata [2].  In addition to two other “semicarinata” populations from the New River drainage, we also included population “ROA” from Mill Creek in Montgomery County (image J), a tributary of the North Fork Roanoke River.

Yes, the Roanoke River is an Atlantic drainage.  And in subsequent years, as the FWGNA survey extended throughout all the Atlantic drainages from Georgia to the New York line, I discovered populations of what I called Goniobasis or Pleurocera semicarinata north down the length of the Great Valley of Virginia, in tributaries of the Roanoke, James, and Shenandoah Rivers as far north as Waynesboro, my home town [10].

This went on for many years.  And at no time, from my initial judgement call in 1980 to maybe perhaps 2010, had I ever studied at any length a bona fide, Midwestern population of semicarinata on the hoof.

In 2010 the FWGNA project began to devote an increasing amount of our attention to the freshwater gastropod fauna of Ohio River drainages.  This led to the population genetic surveys that ultimately disentangled the evolutionary relationships between what had historically been called Goniobasis semicarinata, G. livescens, Pleurocera canaliculata, P. acuta, and Lithasia obovata.  Perhaps the most striking result of those studies was the tremendous ecological adaptability of what we now call Pleurocera semicarinata – populations now known to inhabit the entire range of waterbodies in the Midwest, from the smallest creeks to the grandest rivers, including lake shores of both sand and rock.  In addition to this, or perhaps because of this, populations of bona fide P. semicarinata demonstrate tremendous plasticity of shell morphology.

That plasticity certainly extends to cover the shell morphology demonstrated by what I had been calling semicarinata in the Great Valley of Virginia.  But 30 years of field experience had impressed upon me that Virginia populations seem to be entirely restricted to small creeks.  They do not extend into larger rivers or lentic bodies of water of any sort, nor do they demonstrate anywhere near the range of shell phenotypic plasticity.  There also seemed to be body color differences – the Midwestern populations typically demonstrating a brighter orange coloration and the Virginia populations darker.  I’m not entirely convinced of this, but it is worth mentioning.

And in 2014 we extended the FWGNA survey into the Ohio drainages of West Virginia.  There really are no Pleurocera populations of any species inhabiting any tributaries of the Kanawha river through most of the state.  The Virginia populations I had been calling semicarinata appear to be isolated by over 200 km of uninhabited waters from the nearest bona fide semicarinata population in Ohio.

So all that, together with the genetic results shown in 2014 Figure 4 reproduced above, combined to force me into describing a new species, in the appendix of the first hardcopy volume of the FWGNA project, coming soon [11].  This new species, Pleurocera shenandoa, is locally quite common and widely distributed throughout a long-settled part of the world, where one might reasonably expect the biota to be well-known and well-characterized.

It is not.  Perhaps the primary theme of my 20 years of blog posts, and the entire set of four FWGNA volumes to be published soon, is that even here in the 21st century, in the home of the best science the world has ever known, we remain stunningly ignorant of even the most commonplace.  We spend billions of dollars shooting space probes to the moons of Jupiter, and not a nickel to understand the little brown snails in the creeks behind our own houses.  Shame on us all.


[1] Dillon, R. T. Jr. (2011)  Robust shell phenotype is a local response to stream size in the genus Pleurocera (Rafinesque 1818). Malacologia 53: 265-277. [PDF] See:
  • Goodrichian taxon shift [20Feb07]
  • Goodbye Goniobasis, Farewell Elimia [23Mar11]
[2] Dillon, R. T., Jr.  (2014) Cryptic phenotypic plasticity in populations of the North American freshwater gastropod, Pleurocera semicarinata.  Zoological Studies 53:31. [PDF] See:
  • Elimia livescens and Lithasia obovata are Pleurocera semicarinata [11July14]
[3] Dillon, R. T., Jr (Dillon, R. T. (2016) Two reproductively isolated populations cryptic under Pleurocera simplex (Say, 1825) inhabiting Pistol Creek in Maryville, Tennessee.  Ellipsaria 18(2): 15-16. [PDF]
  • The cryptic Pleurocera of Maryville [13Sept16]
Dillon, R. T. & J. D. Robinson (2016) The identity of the "fat simplex" population inhabiting Pistol Creek in Maryville, Tennessee.  Ellipsaria 18(2): 16-18. [PDF]
  • The fat simplex of Maryville matches type [14Oct16]
Dillon, R. T. (2016)  Match of Pleurocera gabbiana (Lea, 1862) to populations cryptic under P. simplex (Say, 1825).  Ellipsaria 18(3): 10 - 12.  [PDF]
  • One Goodrich missed: The skinny simplex of Maryville is Pleurocera gabbiana [14Nov16]
[4] Dillon, R. T., S. J. Jacquemin & M. Pyron (2013) Cryptic phenotypic plasticity in populations of the freshwater prosobranch snail, Pleurocera canaliculata.  Hydrobiologia 709: 117-127.  [PDF]  See:
  • Pleurocera acuta is Pleurocera canaliculata [3June13]
  • Pleurocera canaliculata and the process of scientific discovery [18June13]
[5] Dillon, R.T. and G.M. Davis (1980) The Goniobasis of southern Virginia and northwestern North Carolina: Genetic and shell morphometric relationships. Malacologia 20: 83-98. [PDF]

[6] Sweet, gauzy memories of my college days:
  • To identify a Physa, 1975 [6May14]
[7] Goodrich, C. (1940) The Pleuroceridae of the Ohio River system.  Occas. Pprs. Mus. Zool. Univ. Mich. 417: 1-21.

[8] Goodrich, C. (1942) The Pleuroceridae of the Atlantic Coastal Plain.  Occas. Pprs. Mus. Zool. Univ. Mich. 456: 1-6.

[9] 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 the agency in 1982.  It was also serially published in the journal Walkerana (1980, 1982, 1988) and finally as stand-alone volume in 1989 (Malacological Publications, Hamburg, MI).

[10] Sweet, gauzy memories of Waynesboro, VA.  Well, not so much:
  • The Clean Water Act at 40 [7Jan13]
[11] Dillon, R. T., Jr. (2019) Description of a new species of freshwater snail (Caenogastropoda: Pleuroceridae) from the Great Valley of Virginia.  Appendix 1 in Dillon, Ashton, Reeves, Smith, Stewart & Watson, The Freshwater Gastropods of North America, Volume I.  Atlantic Drainages, Georgia through Pennsylvania.  FWGNA Publishing, Charleston, SC.

Friday, February 15, 2019

Dates of Publication

Editor’s Note – This brief post is offered as an appendix to my essay of 6Feb19, “Ferrissia fragilis (Tryon 1863).”

Several of you have pointed out, in separate correspondence with me over the last week, that taxonomic priority is established not by date of oral presentation, but by date of publication.  This does not change the order of the three freshwater limpet descriptions I reviewed in my essay of 6Feb19, nor indeed anything in my essay at all.  But for the record, the precise, formal publication dates of the three limpet taxa I discussed in that essay were: 
  • Gundlachia californica Rowell, (31)May1863
  • Ancylus fragilis Tryon, 13July1863
  • Gundlachia meekiana Stimpson, (31)Dec1863
Our good buddy Dr. Harry Lee, from Jacksonville (FL), is quite the gifted scholar.  Yesterday morning he sent me a thoroughly-researched letter on the subject, together with supporting documentation, which I have made available from the links below: 
  • Letter from H. G. Lee, regarding the nomen Ferrissia fragilis [pdf]
  • Extract from Levinton et al. (2010) [pdf
And to be clear.  Just because I myself am not a priest, nor a scribe, nor a Pharisee does not mean that I don’t value the services they can provide.  Everybody appreciates a scribe now and then.  Thanks, Harry!

Wednesday, February 6, 2019

Ferrissia fragilis (Tryon, 1863)

At 9:30 on the starry but moonless night of April 16, 1863, seven armored gunboats under the command of Admiral David Porter, accompanied by three army transports and a steam ram, began a stealthy voyage down the Mississippi under the guns of Vicksburg.  Water-soaked bales of hay were stacked around their boilers and pilot houses, and coal barges lashed to their starboard flanks.  At 11:10 PM, all hell broke loose [1].

Wikimedia Commons
On the evening of April 20, four days later, the regular biweekly meeting of the California Academy of Natural Sciences convened at 622 Clay Street, San Francisco, seven members present, Dr. Trask in the chair.  Dr. Cooper communicated the description of a new mollusk, recently discovered by Rev. Joseph Rowell in the waters of the Feather River, Gundlachia californica [2].  Images of the little limpet, “length about sixteen one-hundredths of an English inch,” showed a shell apex distinctly different from the embryonic shell origin.  Philip Lutley Sclater, Esq., of London was elected a corresponding member, three species of reptiles from San Mateo added to the cabinet, and the Academy adjourned.

Shortly after 5:00 on the evening of May 2, 1863, the troops on the right flank of General Joseph Hooker’s army at Chancellorsville, VA, stacked their rifles and began to prepare their suppers.  They were amused to see large numbers of deer and rabbits break out of thickets to the west and come bounding toward them.  The men cheered and waved their caps at the startled forest creatures, until the next thing they saw froze the laughter in their throats.  Total casualties at the end of the battle were 3,500 killed and 19,000 wounded.

May 2, Just before dawn.  Wikimedia commons
A bit more than two weeks later, on the afternoon of May 26, 1863, The Academy of Natural Sciences of Philadelphia convened for its regular weekly meeting, 19 members present, Mr. Lea in the chair.  The agenda was lengthy: 9 papers presented and ordered to be published, including an ambitious contribution by T. B. Wilson & J. Cassin proposing a third kingdom of life, the Primalia.  Mr. George W. Tryon read a paper describing seven new species of freshwater gastropods, finishing with Ancylus fragilis [3].  The 4 millimeter limpet, apex elevated, acute and “curved backwards,” had been sent to him from California by Rev. J. Rowell.

On June 3, 1863, General Robert E. Lee began to concentrate his army of 75,000 at Culpeper, in preparation for an invasion northward.  And on the morning of June 8, Union General Alfred Pleasonton probed south across the Rappahannock with six brigades of cavalry, approximately 10,000 horsemen, to gauge Lee’s disposition.  Around noon Pleasonton encountered a roughly equal force of confederate cavalry under Gen. Jeb Stuart at Brandy Station.  Sabers, pistols, and carbines flashing in the sun, the largest cavalry engagement ever fought on American soil was underway.

Cavalry Charge Near Brandy Station, by Edwin Forbes.
Two weeks later, on the afternoon of June 17, the Boston Society of Natural History convened at Tremont Street, Prof. Wyman in the chair.  Mr. Stimpson read a paper on the genus Gundlachia, in which he counted five species, including G. californica, described just two months prior [4].  He went on to describe a sixth species, G. meekiana, collected from the vicinity of Washington DC, similar in all respects to G. californica, but with a less ovate aperture.  One additional paper was read, two communications received, six donations to the museum logged, and the Society adjourned.

Admittedly, the little brown pulmonate limpet that we today call Ferrissia fragilis is not the most striking element of the North American malacofauna.  It is, however, the fourth most common freshwater gastropod in the Eastern United States, behind Physa acuta, Campeloma decisum, and Menetus dilatatus [5].  Populations of Ferrissia fragilis are ubiquitous on aquatic vegetation and organic debris in every lake, pond, and riverine backwater nationwide, Canada to Mexico, sea to shining sea.  Including at the mouth of Pennypack Creek, in north Philadelphia.

Why do you suppose that these exceptionally abundant and wide-ranging little gastropods were completely overlooked by every American biologist working in every puddle of fresh water for half a century, and then simultaneously discovered by three completely separate societies of learned men, meeting in San Francisco, Philadelphia, and Boston, during a single eight-week period of 1863?  What might account for the sudden, passionate interest among young well-born gentlemen of the urban North in freshwater limpets?  I will leave that question to the speculation of my readership.

The Bartow County Yankee Killers [6]
I will, however, take a paragraph to remind you all of several previous essays touching upon Ferrissia fragilis [7].  You may recall, from my essays of 10June09 and 9Nov12, that the freshwater limpets were a particular research interest of Bryant Walker’s (1856 – 1936), and that the definitive monograph was contributed by Paul Basch in 1963 [8].  Both Walker and Basch recognized Ferrissia fragilis as a widespread and important element of the North American malacofauna, and listed californica (Rowell 1863) and meekiana (Stimpson 1863) as junior synonyms of fragilis (Tryon 1863).  And you may also remember my essay of 8Dec10 reviewing the excellent work of Andrea Walther and colleagues [9] synonymizing several additional well-known names under fragilis, including walkeri (Pilsbry & Ferris 1906) and mcneilli (Walker 1925).  So that today, the FWGNA Project recognizes just two species of Ferrissia: rivularis and fragilis.

Up until recently it has been quite easy to ignore the extraordinarily trivial and obscure detail that the meeting of the California Academy which heard the description of G. californica preceded the meeting of the ANSP which heard the description of A. fragilis by five weeks.  For some reason I cannot fathom, however, here in 2019 it has become less easy.

The issue of the American Malacological Bulletin freshly arrived on my desk last month included a research note announcing the “discovery of the freshwater limpet, Ferrissia californica (Rowell, 1863)” on the Island of Montserrat [10].  Tryon’s nomen “fragilis” does not appear in title, abstract, key words, or the first five paragraphs of its introduction.

Do systematic biologists of the 21st century feel some heightened sense of obligation to the Rev. Rowell, now asleep in Christ for 100 years?  Have our oaths to uphold the International Code of Zoological Nomenclature suddenly become more solemn?  Is the iron fist of the ICZN Commission grown more fearsome?

I do not know.  I am neither priest nor scribe nor Pharisee, I am a scientist.  The names I assign to populations of freshwater gastropods are hypotheses of evolutionary relationship – my best hypothesis, without compromise.  If I find that more than one name has been assigned to a population or group of populations, each of which conveys the same evolutionary hypothesis, I will select the name that, in my judgement, conveys my hypothesis to the broadest audience. 

That name, in the case of the 4 mm freshwater limpets with the eccentric shell apex, is Ferrissia fragilis (Tryon, 1863).  The letter of some legalistic code about which I was not consulted, administered by some commission I do not recall electing, does not enter into the calculation.

But let me hasten to make another point, and to make it as forcefully as I have made the previous one.  I would not presume to impose my selection of any scientific name on anyone else.  In fact, I earnestly hope that other scientists will develop other hypotheses about the evolutionary relationships of the populations I refer to Ferrissia fragilis.  Such a situation would be the mark of an active science.  And if it is the judgement of some other worker that Rowell’s nomen californica transmits information more effectively than Tryon’s fragilis, far be it from me to second-guess.

I have no problem with synonyms.  I do not think that taxonomic synonyms necessarily lead to scientific confusion, any more than I expect the college dean to become confused if I tell him to kiss my peachy-pink posterior or my rosy-red ass, on the way out the door.  Synonyms are pervasive in the English language, and we are richer for it.

Indeed, I think it will be a service to preserve both names.  So just this morning I have added Rowell’s “Ferrissia californica” directly under the header “Ferrissia fragilis” at the top of my FWGNA page.  And entered the nomen into the list of synonyms available from the website pull-down.  And written the present essay, wherein both names are connected.  In this fashion, the future generation of graduate students, perhaps na├»ve about the fragilis/californica situation, will be able to google-up and connect their disparate literatures.

And finally.  Difficult though it may be to understand [11], some non-negligible fraction of my colleagues have, from time to time, associated into committees to develop formal lists of accepted or approved names that we, “the community,” will be sanctioned to apply to the diverse biota of this, our great country.  I would suggest that all members of such committees re-read the first six paragraphs of the present essay.  And get a life, every one of you.


[1] This account of the action at Vicksburg, together with those of Chancellorsville and Brandy Station following, are extracted from Shelby Foote’s (1963) classic The Civil War, A Narrative.  Volume II, Fredricksburg to Meridian. Vintage Books, 988 pp.

[2] Rowell, J (1863) Description of a new Californian Mollusc.  Proceedings of the California Academy of Sciences Series 1, 3: 21 – 22.

[3] Tryon, G. W. (1863) Descriptions of new species of fresh water Mollusca, belonging to the families Amnicolidae, Valvatidea, and Limnaeidae; inhabiting California.  Proc. Acad. Natl. Sci. Phila. 15: 147 – 150.

[4] Stimpson, W. (1863) Malacozoological Notices No. 1, On the genus Gundlachia.  Proc. Boston Nat. Hist. Soc. 9: 249 -252.

[5] This result is from 18,974 records of 99 species in four regions: the Atlantic, the Ohio, East Tennessee, and (very preliminarily) The Cumberland.  Download the presentation here:
  • The freshwater gastropods of The Ohio: An interim report [27June17]
[6] From left, Daniel, John, and Pleasant Chitwood of Company A, 23rd Georgia Infantry.  Daniel and John were captured at Chancellorsville on May 2, 1863.  This image scanned from Miller, W J. & B. C. Pohanka (2006).   An Illustrated History of the Civil War.  Barnes & Noble.

[7] My previous essays on Ferrissia:
  • Just One Species of Ferrissia [10June09]
  • Two Species of Ferrissia [8Dec10]
  • Bryant Walker’s Sense of Fairness [9Nov12]
[8] Basch, P.F. (1963) A review of the recent freshwater limpet snails of North America (Mollusca: Pulmonata). Bull. Mus. Comp. Zool. Harvard Univ. 129: 399–461.

[9] Walther, A. C., J. B. Burch and D. O’Foighil (2010) Molecular phylogenetic revision of the freshwater limpet genus Ferrissia (Planorbidae:Ancylinae) in North America yields two species: Ferrissia (Ferrissia) rivularis and Ferrissia (Kincaidilla) fragilis. Malacologia 53: 25-45.

[10] Coote, T, K. A. Schmidt, R. E. Schmidt, & E. R. McMullin (2018) Discovery of the freshwater limpet, Ferrissia californica (Rowell, 1863) (Gastropoda: Planorbidae), from streams of Montserrat, West Indies, a new addition to the Caribbean fauna.  American Malacological Bulletin 36: 291 – 295.

[11] I myself probably do understand it, however.  I think committees form to standardize the names of the diverse elements of the American biota to facilitate governmental regulation.  And with governmental regulation comes governmental funding.  I don’t want to be cynical – I’m pretty sure my colleagues on such committees think that they are furthering the cause of conservation, and that whatever taxpayer’s dollars might be expended on their salaries are well-justified.  I used to think that, too.