Rhodacmea Ridotto

Editor's Note.  This essay was subsequently published as: Dillon, R.T., Jr. (2019b)  Rhodacmea ridotto.  Pp 149-155 in Freshwater Gastropods of North America Volume 2, Essays on the Pulmonates.  FWGNA Press, Charleston.

The headline news at the AMS meeting in Pittsburgh late last month was the rediscovery of two populations of the rare limpet genus Rhodacmea, together with a reawakening of our collective consciousness regarding this peculiar element of the North American freshwater gastropod fauna. A formal report by Diarmaid O’Foighil and his collaborators in Michigan, Alabama, and Kentucky was published on May 31 in PLos One (1).

In recent years we have often taken note of the excellent research on ancylid limpets issuing from our good friends in Ann Arbor: Diarmaid, Taehwan Lee, Jack Burch, and (until recently) Andrea Walther. Faithful readers will remember the columns we posted in 2007 and 2010 regarding their work on Laevapex and Ferrissia, respectively (2). And just as was the case with those latter genera, the best way to put the new Rhodacmea results into perspective is to back up to the 1963 monograph of another worker with Ann Arbor roots, Paul Basch (3).

Rhodacmea is the most distinctive of the North American ancylids, bearing a shell Basch described as “strangely indented” and a “peculiar” radula with heavy inner cusps as well as the usual (more delicate) outer ones. Basch asserted, “The genus in North America undoubtedly represents a branch of the basic Ancylus stock, related to European Ancylus fluviatilis,” a hypothesis that modern molecular data seem to bear out. He recognized three species: R. filosa (tall, ribby and thin - Basch's figure above), R. eliator (tall, smooth and robust - Basch's figure below), and R. hinkleyi (with a lower apex, not important for our story here). The historic ranges reviewed by Basch centered all three species in big rivers of the Alabama and Tennessee systems, although eliator was originally described from the Green River of Kentucky.

But by 1963 Basch observed,

“The genus is undoubtedly approaching extinction as more and more fast-flowing, larger streams and rivers in the southeastern United States are rendered unsuitable as habitats by dams and pollution… I have collected in dozens of streams in these areas and have located living Rhodacmea only in the Cahaba River near Helena, Alabama.”

Modern records are indeed very scarce (4). The IUCN Red List declared R. filosa extinct in 2000.

Seen in that light, the biggest news from Pittsburgh may have been the rediscovery of viable populations of Rhodacmea in Choccolocco Creek (a Coosa tributary about 100 km east of the Cahaba) by our colleague Paul Johnson, and in the Green River by our colleague Ryan Evans. These are valuable biodiversity resources, and well worthy of conservation.

The glad tidings have been somewhat tarnished, however, by their scientific treatment at the hands of our colleagues in Ann Arbor, which (I fear) expose the rather shabby undergarments of the harlequin we conservation biologists too often seem to play. For both in their AMS presentation this past month, and in their recently published paper, O’Foighil and his colleagues assert that all three of their Rhodacmea populations “merit specific status” separately.

Of course, historically all the freshwater limpet species have been recognized entirely by shell morphological criteria. On that basis, Basch identified the Cahaba population as R. eliator. And Anthony’s (1855) type locality for R. eliator was the Green River of Kentucky. That is why, as I understand it, a directed search was undertaken there. And the formal morphometric study published by O’Foighil and colleagues returned no significant difference between the Cahaba and Green River eliator populations.

The level of CO1 sequence divergence between Cahaba and Green is also small, when compared to values these same researchers have obtained among conspecific populations of Ferrissia and Laevapex. Judging from the scale bar on their CO1 gene tree (click for larger) the O’Foighil group found perhaps 5-6% sequence divergence among all haplotypes sampled from all three Rhodacmea populations – Cahaba, Green, and Choccolocco. Compare this to the divergence shown among Laevapex fuscus haplotypes – easily in the 10 - 13% range. So given both negligible morphological difference and negligible sequence divergence (5) between the Cahaba and Green River Rhodacmea populations, how can our colleagues assert that they represent different species?

The reasoning offered by O’Foighil et al. to support their three-species hypothesis pirouettes about the Choccolocco population, individuals from which apparently bear sufficient ribs on their shells to support their identification as R. filosa. Our colleagues seem deeply invested in the proposition that this population cannot be conspecific with the previously-known Cahaba population, issuing press releases trumpeting their rediscovery of a unique species in Choccolocco Creek believed extinct for 60 years (6). So since Choccolocco must be a different species from Cahaba (at less than 1% sequence divergence!), the Green population (at 6% divergence) must represent a third.

They further reason that the Green River population must be the true eliator (since that is the type locality) and Cahaba must be a cryptic species Basch did not recognize. The old name cahawbensis seems conveniently available for rescue from synonymy.

But regarding the plasticity of shell characters in freshwater limpets, I can do no better than quote our Ann Arbor colleagues themselves (7): “Shell shape and sculptural features … are unreliable phylogenetic indicators, and they presumably (8) encompass a large ecophenotypic component.” I will also note that the morphometric analysis around which this entire commedia dell' arte turns included just N=2 bona fide individuals from Choccolocco, combined with N=6 museum specimens from a fourth (extinct) population of the author’s own choosing. And does crediting shell characters when they split Choccolocco and Cahaba, but discounting them when they lump Cahaba and Green, seem a trifle disingenuous to anybody else?

Perhaps there is some more profound reason that our colleagues have recognized three species of Rhodacmea, where they have seen only single species in Laevapex and Ferrissia, given similar evidence? A cynic would note that it is easier to get funding for three endangered species than one. But knowing our colleagues as I do, I feel sure that their motivation was the finest – to maximize the likelihood that these populations, by whatever names they may be called, will be conserved into the future. Their ends do not, however, justify their means.


Notes

(1) O'Foighil, D. O., J. Li, T. Lee, P. Johnson, R. Evans, & J. B. Burch (2011) Conservation genetics of a critically endangered limpet genus and rediscovery of an extinct species. PLoS One 6 (5): e20496. [html]

(2) Phylogenetic sporting and the genus Laevapex [20July07]
Two species of Ferrissia [8Dec10]

(3) Basch, P. F. (1963) A review of the recent freshwater limpet snails of North America (Mollusca: Pulmonata). Bulletin of the Museum of Comparative Zoology 129: 399 - 461.

(4) Although there are 1978 collections of R. filosa from Choccolocco Creek in the Florida Museum of Natural History.

(5) I will resist the temptation to preach my "gene trees are not species trees" sermon here. But sinners should prayerfully consider my post of [15July08].

(6) The news seems to have been picked up by Science Daily in early June, and spread to a variety of web-based outlets serving the conservation community, such as terradaily.com, redorbit.com, and batangastoday.com. The headlines in all cases are to the effect that a "Snail Long Thought Extinct Isn't." The Green River population is not mentioned in any of these secondary reports.

(7) Walther, A., T. Lee, J. B. Burch, and D. O'Foighil. 2006. E Pluribus Unum: A phylogenetic and phylogeographic reassessment of Laevapex (Pulmonata: Ancylidae), a North American genus of freshwater limpets. Molecular Phylogenetics and Evolution, 40: 512.

(8) Presumption is not necessary here. I reviewed our common garden experiments with ancylid limpets in my post entitled, “Just One Species of Ferrissia.” [10June09]

What Is A Species Tree?

Editor's Note.  This essay was subsequently published as: Dillon, R.T., Jr. (2019b)  What is a species tree?  Pp 199-206 in The Freshwater Gastropods of North America Volume 2, Essays on the Pulmonates.  FWGNA Press, Charleston.

Back in July of 2008 (1) we reviewed the relationship between gene trees and species trees, a subject that has become fashionable at the highest levels of evolutionary science. The phenomenon that leads to differences between the two types of evolutionary tree is usually called “lineage sorting” by phylogenetic systematists, who otherwise ignore it, hoping it will go away. But population geneticists, who tend to run their gene trees backward and call the phenomenon "coalescence," have pointed out that the differences in a set of gene trees can be used to date divergence events in a species tree. This may be the one thing that gene trees are actually good for.

But what is a "species tree?" Wayne Maddison, in his seminal 1997 paper on the subject (2), had in mind a phylogeny of bona fide biological species, "when reproductive communities are split." But reproductive isolation need not evolve between a pair of populations for lineage sorting to commence in their gene pools. The clock starts ticking on the gene trees as gene flow becomes disrupted for any reason between any pair of populations, reproductively isolated or not. So although the scientific community most actively involved in this area of research has always used the term "species tree" to describe the phylogeny they are comparing to their gene trees (3), the term "population tree" would clearly be much more accurate.

Genuine species trees turn out to be surprisingly difficult even to visualize, much less to work out. I did not appreciate the difficulty myself until I tried to draw one, or actually a set of them, for the paper Amy Wethington, Chuck Lydeard, and I recently published in BMC Evolutionary Biology (4).
Our new paper summarizes over ten years of research we've conducted on the evolution of reproductive isolation in Physa, including papers we've published comparing Charleston P. acuta, P. gyrina, P. pomilia, and P. carolinae (5). Brand new for 2011 we've added a second population of P. acuta, sampled from Philadelphia.

Here's an obvious attribute of the word "species" that I think we may all take too much for granted. The word "species" is relational, like the word "brother." It is not a point-character that can be measured on an OTU and cast simply on a phylogenetic tree. So when Amy, Chuck, and I undertook to add a second population of P. acuta to the species tree we had been building for years, we added a row to our triangular matrix. Between acuta, carolinae, pomilia and gyrina there are 3+2+1=6 sets of pairwise mate choice tests to be completed, and 6 corresponding sets of no-choice hybridization experiments. Adding the Philadelphia acuta population added 4 more sets of both, almost doubling our effort. A pain in the butt.

And here’s another bullet point we might profitably highlight before drawing our first species tree. The single, original population at the base of our hypothetical tree was (of course) reproductively compatible with itself. What evolves, as a species tree splits, is reproductive incompatibility. So (to borrow a term from cladism, which I hate) retention of reproductive compatibility is a "symplesiomorphy." I can still remember the day back in the early 1980s when an ANSP ichthyologist first called my attention to a paper by Donn Rosen rejecting the biological species concept because an ideologically pure classification cannot be based on symplesiomorphy (6). I'm still pissed off about that.

In any case, I should think that most of us, if we were to visualize a bona fide species tree, would begin with something like tree (c) at left for F1 fertility in Physa. No hybrids were recovered from any of the no-choice experiments testing gyrina against any of the other four populations, so gyrina is not shown in tree (c). At least some hybrids were born in the other 3+2+1 experiments, the ones between Charleston acuta-c and Philadelphia acuta-p proving perfectly fertile, the other 3+2 categories of hybrids not. So starting with hybrid fertility at the base of the tree, the situation may have been as simple as two separate mutations evolving at a single locus, from fertile to sterile. The actual phenomenon in Physa is almost certainly controlled by multiple loci, but our observations can be modeled very simply, as just the one.

The situation cannot be so simple for hybridization, however. Of course the Charleston acuta-c and the Philadelphia acuta-p will hybridize, and as we just noted, gyrina does not hybridize in our experimental conditions with any of the other species at all (7). Our Physa carolinae population freely hybridizes with either population of acuta, while P. pomilia partially hybridizes with either population of acuta, yielding mixtures of selfed and outcrossed F1 progeny. Our carolinae x pomilia no-choice experiments have not yielded any hybrids.

My best effort to depict this messy set of relationships is shown in tree (b) at right above. Our model suggests two loci, a "complete" locus J and a "partial" locus K, at which unique compatibility alleles segregate, locus J epistatic over locus K. See the text of our paper for the details. The bottom line is, however, that the simplest model I can conceive of for the evolution of barriers to hybridization in Physa is not especially simple.

Nor is the situation on the evolution of sexual incompatibility simple, at all. Although our mate choice tests did show prezygotic reproductive isolation between P. carolinae and Charleston acuta-c, no behavioral barriers seem to be in place to lower the frequency of copulation between carolinae and Philadelphia acuta-p. Those observations seem to require another two-locus model (tree d), again see our paper for the gory details.

Our paper has a very mild conclusion, given the years of sturm und drang through which we passed to arrive upon it. The three species trees shown above, with their minimum of five genes for reproductive isolation as postulated, do indeed match the CO1+16s mtDNA gene trees previously published by Wethington & Lydeard and Wethington et al (8). I was kind-of hoping that they would not, because our conclusions would have been cooler. But (try as I might) I cannot rearrange the three species trees shown above to make them any simpler, to not match the gene tree.

I'm sure this isn't the first time in the history of science that the relationship between gene trees and bona fide species trees has ever been tested, but I don't know of any other. And the match seems to be a good one, darn it. But I am not issuing a warrant to all you gene tree jocks out there to get cocky.


Notes

(1) Gene Trees and Species Trees [15July08]

(2) Maddison, W. 1997. Gene trees in species trees. Systematic Biology, 46, 523-536.

(3) For example see Hudson, R. R. (1992) Gene trees, species trees, and the segregation of ancestral alleles. Genetics 131: 509-512. Wakeley, J. (2008) Coalescent Theory, An Introduction. Roberts & Co., Greenwood Village, CO 326 pp. Degnan et al. (2009) Properties of consensus methods for inferring species trees from gene trees. Syst. Biol. 58: 35-54.

(4) Dillon, R. T., Jr., A. R. Wethington & C. Lydeard (2011) The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail Physa. BMC Evolutionary Biology 11:114.
Online clickable version [html]
Standard [pdf]

(5) Dillon, R.T., Jr., Robinson, J. & Wethington, A. 2007. Empirical estimates of reproductive isolation among the freshwater pulmonate snails Physa acuta, P. pomilia, and P. hendersoni. Malacologia, 49, 283-292. [pdf] Dillon, R. T., Jr., Earnhardt, C. & Smith, T. 2004. Reproductive isolation between Physa acuta and Physa gyrina in joint culture. American Malacological Bulletin, 19, 63-68. [pdf] Dillon, R. T., Jr. 2009. Empirical estimates of reproductive isolation among the Physa species of South Carolina (Pulmonata: Basommatophora). The Nautilus, 123, 276-281. [pdf] That last paper was featured in my blog post entitled "True Confessions: I described a new species" [7Apr10]

(6) Rosen, D. E. (1979) Fishes from the uplands and intermontane basins of Guatemala: revisionary studies and comparative geography. Bull. Amer. Mus. Nat. Hist. 162: 270-375.

(7) Although we recovered no hybrids from our no-choice experiments published in 2004, Tom Smith and I did discover a couple acuta x gyrina hybrids naturally occurring on the margins of the Delaware River at Washington Crossing. They showed up quite unexpectedly on allozyme gels. That's all I know, until God grants me another life, or a few more good students.

(8) Wethington AR, Lydeard C (2007) A molecular phylogeny of Physidae (Gastropoda: Basommatophora) based on mitochondrial DNA sequences. J Moll Stud 73: 241-257. [12Oct07]Wethington AR, Wise J, Dillon RT Jr (2009) Genetic and morphological characterization of the Physidae of South Carolina (Pulmonata: Basommatophora), with description of a new species. Nautilus 123: 282-292. [pdf]

Collecting Freshwater Snails by Kayak

About five or six years ago my family gave me a modest kayak as a Christmas present, and shortly thereafter I began carrying it with me on field trips. The first thing I learned was, "Paddle upstream."

The second thing I learned was, if at all possible, do not try to collect freshwater snails from a kayak. There is almost no space inside, and freedom of movement is very constrained. And even such an elementary operation as, “to pick up a submerged stick” without at least two fixed points against which to pick is a genuine education in basic physics.

But much of the freshwater habitat around Charleston is not really “wadeable.” And it is amazing how rarely the portions of large rivers that are readily accessible by motorized vehicle constitute especially productive freshwater snail habitat. And how often the spot just across the river, upstream 100 meters, looks absolutely perfect, at least staring at it from a boat ramp, with one's hands on one's hips. So I have found my kayak quite useful simply as a mode of transportation, to carry me somewhere better, so I can get out.

That being said, there are some habitat types that are indeed conveniently sampled by kayak. Swampy areas with soft and flocculent bottoms come to mind, and especially aquatic macrophytes, either the submergents like Elodea and Hydrilla, or floating emergents like water lilies, pondweeds, and Ludwigia (above). Mats of such vegetation can sometimes float over treacherous bottoms, and I can't think of any better method to sample the little pulmonates and hydrobiids they often shelter unless from a low, shallow-draft boat like a kayak.

The idea of tying a dipnet onto the stern of my kayak was pretty obvious. I took a triangular kick net off its pole because it fit under those big black cargo bands on the stern of my particular brand of kayak, but I suppose a D-shaped net head would have advantages as well.

When I brought my first net samples into my kayak, however, I discovered that there was really no place to sort through them except in my lap. And if I was holding my net with one hand and picking through its contents using forceps with the other, where would I perch the little vials I was trying to transfer my little pulmonates and hydrobiids into? And what to do with my paddle?

So I cut myself a 20” sorting table out of 1x10” board, and drilled a couple holes in it to hold 21x70 mm vials. On one edge of the board I attached a metal flange, which hooks under the lip of my kayak. And on the other corner I attached a metal bracket, which holds my paddle.

The paddle is actually supported both by the bracket on the corner of my sorting table and by a coat hanger I’ve bent into a hook and attached to the bow of my kayak (visible in the Ludwigia shot above - click for larger). Thus the weight of the paddle on the one edge of my table keeps the metal flange on the other edge firmly hooked under the kayak lip.

The picture below shows the sorting table in place, counter-weighted by the paddle (click for larger). I keep extra vials in an ice cube tray underneath my seat. I always wear forceps on a string around my neck, regardless of whether I am on land or sea. When I’m not sampling I slide the sorting table behind my seat, where it doubles as a backrest. (I took the factory-installed backrest out of the kayak several years ago.) The nice photo of spider lilies on the Catawba River at the top of this post shows the table in its stowed position.

That's really all the advice I've got, except for the usual, generic reminders about a life jacket, a hat, and sunscreen. Oh, and paddle upstream first. I'm serious about that.

Megapetitions II: Armistice Day?

Faithful readers should remember the yarn we spun back on 14July09 entitled, “Megapetitions of the Old West” (1). Who could forget riding sidekick with gunslingers from the Center for Biological Diversity through the badlands of endangered species politics, filing petitions to list hundreds of species in a single crank of our solar-powered fax machines, firing off lawsuits on the 366th day as 12-month deadlines came and went?

In our last episode, the CBD posse had filed a (2008) petition nominating “32 mollusk species from freshwater and terrestrial ecosystems of the northwestern United States” and a (2009) petition to list “42 species of Great Basin Springsnails” under the provisions of the endangered species act. So now almost two years later, how has that megapetitiony, lawsuity thing been working out?

Reference to the ecos.fws.gov website reveals that none of the 74 mollusk species petitioned by the CBD in 2008 or 2009 has advanced beyond “under review – no findings.” Only two species of freshwater snails have in fact been federally listed since 2005 – the two Alabama pleurocerids we featured in late 2009 (2). Indeed, no species of freshwater gastropod has been added to the formal list of candidates maintained by the US Fish and Wildlife Service since 2002 (3).

Undeterred, on April 20, 2010, the Center for Biological Diversity filed a single, massive, 1145 page “Petition To List 404 Aquatic, Riparian And Wetland Species From The Southeastern United States As Threatened Or Endangered Under The Endangered Species Act” (4). This stupendous ark-full of creatures great and small included 4 mammals, 3 birds, 28 herps, 48 fish, 55 insects, 92 crustaceans, 48 mussels and 44 freshwater gastropods from a twelve-state region. Among the gastropods, I have tallied 27 pleurocerids, 15 hydrobiids, 1 ancylid and 1 planorbid (5).

And exactly 12 months and one day later, on April 21, 2011, the CBD filed a notice of intent to sue the US Fish and Wildlife Service to have determinations made for these 404 species. “The Obama administration seems intent only on delay and inaction,” said Sheriff Noah Greenwald. “It’s dangerous foot-dragging — yet another result of an endangered species program that’s been broken for more than a decade and badly needs reform.”

Now pardners, I know just enough about the world of politics and public policy to know how little I know about politics and public policy. And I know even less about the New York Times. But last week a colleague sent me a link to a NYT article entitled, “U.S. Reaches a Settlement on Decisions about Endangered Species,” the timing of which does not seem to be a coincidence (6).

There is apparently at least one other organization very similar to the CBD in both its cause and its approach, styling itself “WildEarth Guardians.” The WEG is also a primarily western outfit focusing on endangered species protection, and in fact rode with the CBD posse in the successful campaign to list Pyrgulopsis roswellensis, Juternia kosteri and Assiminea pecos back in 2005.

So quoting now from the FWS press release (7), last week WildEarth Guardians signed an agreement formalizing a “listing work plan that will enable the agency to systematically, over a period of six years, review and address the needs of more than 250 species listed on the 2010 Candidate Notice of Review.” That would be good news for the 11 freshwater gastropods (entirely western hydrobiids) currently on that formal list of candidates (3).

But it does send 1,230 species more recently petitioned by organizations such as the Center for Biological Diversity to the back of the line. And the CBD was not pleased. According to the New York Times, similar negotiations between the FWS and the CBD “reached an impasse” sometime in April. Sheriff Greenwald was quoted as opining that the FWS failure to keep pace with petition candidates for the endangered species list was more of a reflection of a lack of political will than distractions posed by excess litigation.

Perhaps this is a variant of the old “good cop / bad cop” strategy that could more descriptively be termed, “crazy cop / cop who is merely unreasonable.” Does the spectacle of a genuinely insane Center for Biological Diversity - firing sixshooters into the air like Yosemite Sam - make negotiation with an organization that is simply shrill, such as WildEarth Gardians, politically possible? Even if that has not been the strategy here, it seems to have worked.

Notes

(1) Megapetitions of the Old West [14July09]

(2) We featured the listing of Leptoxis foremani and Pleurocera foremani in a series of four posts on the Mobile Basin: Two pleurocerids proposed for listing [14Aug09], Leptoxis lessons [15Sept09], Pleurocera puzzles [12Oct09], Goniobasis WTFs [13Nov09]

(3) The FWS reviews its formal list of candidate species annually. A PDF of the most recent (10Nov10) "Candidate Notice of Review" can be downloaded here [PDF]. See pp 69255-58 for the freshwater snails.

(4) Here's the page at The Center for Biological Diversity:
The Southeast Freshwater Extinction Crisis
There are links from that page to an interactive map and an "action timeline" of lawsuity stuff, as well as to the entire 1,145 page petition itself.

(5) If you can believe it, the CBD petition itself includes no tabulations of any sort for the 404 species proposed. The 1,100-page list is organized alphabetically by genus. I made my tally of the 44 freshwater gastropods covered by visiting the 12 state pages separately, using the interactive map. Here's a PDF table I created [CBD-southeast-endangered.pdf] freshly updated as of 7Oct11. Only 8 states are represented - no freshwater gastropods listed from VA, WV, SC, or LA.

(6) U.S. Reaches a Settlement on Decisions about Endangered Species [NYT 10May11]

(7) Fish and Wildlife Service Announces Work Plan to Restore Biological Priorities and Certainty to Endangered Species Listing Process [FWS 10May11]

Malacoterrorist Watch List!

Editor’s Note – This essay was subsequently published as: Dillon, R.T., Jr. (2019d) Malacoterrorist Watch List!  Pp 131 - 135 in The Freshwater Gastropods of North America Volume 4, Essays on Ecology and Biogeography.  FWGNA Press, Charleston.

I will open this essay with a confession, of sorts. On the afternoon of 6Mar11 I, Dr. Robert T. Dillon Jr., did in fact collect a small sample of freshwater gastropods from a filthy stream in the little town of Ojojona, south of Tegucigalpa. I recorded Stenophysa marmorata (5), Biomphalaria obstructa, and Uncancylus concentricus, not being terribly sure about those last two identifications. That's a disposable diaper floating about 2-3 feet in front of my right hand down there [click for panorama].

Strangely, none of the citizens of Ojojona seemed to show the slightest interest in what I was doing, squatting down in their little creek like that, even though a steady stream of pedestrians passed by on the bridge above me. In fact, one older gentleman came down the bank, unzipped, and pissed in the creek right behind me, without offering so much as a word of greeting.

Now I am quite familiar with certain regulations promulgated by US Customs and Border Protection regarding snails. Question 11c on the blue Customs Declaration Form which all arriving travelers must complete specifically inquires whether "I am (we are) bringing disease agents, cell cultures, or snails" into the United States. My answer last month was NO. By the date of my flight home, the sample I took from that little stream in the hills above Tegucigalpa had long been preserved in denatured ethanol and stowed in a white plastic bottle, deep in my day pack, in my checked luggage. That sample was no longer "snails." It had become "specimens for scientific research." That's my story, and I'm sticking to it. [Click the image below to see the full front of the form.]

Did I look guilty, approaching the Immigration desk in Atlanta? I handed the officer my passport, with blue customs declaration inside. He asked me just one or two very harmless questions, including my occupation, stamped my passport, and welcomed me home to the USA.

Did I transmit some sort of telltale body language as I waited to pick up my checked baggage? Did I glance around furtively as I rolled my luggage back through the corridor to where the US Customs Officer was sitting calmly on his stool, retrieving declaration forms? How did he know my name?

As I approached the Customs Officer he rose and asked if I were "Mr Dillon, the college professor from Charleston?" Yes, I admitted that I was. He then asked me pointedly, "Are you bringing any snails with you this afternoon?"  No, I replied, I was not. My Customs Declaration clearly stated that I was not. I had made no mention of snails to anybody, official or otherwise, not even a whisper. Yet somehow, it was to materialize, I had been profiled as a Malacoterrorist!

The officer placed my passport and customs declaration in a clear vinyl pouch and instructed me to roll my luggage through the doors to my right, reporting to the third desk on the left. There to greet me was a stern and stubby woman of Hispanic descent, who asked me to open all my bags and began to inspect them thoroughly, all the while asking, "Do you have any snails? Do you understand that you must have a permit to import snails? Do you understand that any and all snails you might be carrying must be declared?"

Eventually she dumped all the stuff out of my day pack, and briefly held the white plastic bottle in which my specimens for scientific research were preserved. But she didn't think to open the top and look inside. "Are you certain that you are not carrying any snails?" she inquired again. And again I insisted that no snails were in my possession. That's my story, and I'm sticking to it.

My entire detention didn't take much more than ten or fifteen minutes, after which I was released on my own recognizance, irritated (and perhaps a bit humiliated) but otherwise unscathed. And puzzling, as I dragged my recognizance through the airport to my connecting flight, as to how the Feds might so accurately have profiled me, without any overt clues, as a Person of Malacological Interest.

Some of my readership may remember the essay I published on 17Dec08 entitled, "Non-pests, Non-plants, and Non-sense at the USDA" (1). In that essay I described a series of misadventures and hijinks attending my efforts to obtain a USDA permit for the importation of living European planorbid gastropods into the United States. The process was painful and took several months to bear fruit, but ultimately I was granted a "letter of no jurisdiction" by the USDA to facilitate that particular shipment of snails. In retrospect, I feel fairly certain that this honest effort at good-faith citizenship in 2008 may have led to my detention in Atlanta last month. And am I to suffer this same indignity every time I apply to re-enter my own country for the rest of my life?

I like to think of the proper relationship between Science and The State as one of dialogue (2). As a scientist, I understand that my language, culture, and values are different from those of US Customs and Border Protection, US Immigration & Customs Enforcement, and our various federal agencies concerned with agriculture, public health, and natural resources. Nevertheless, a couple years ago I coauthored a paper with USDA colleagues on mollusks of quarantine importance in the United States (3). And just last week the US Fish & Wildlife agent on duty here in Charleston contacted me (yet again) to confirm the identity of some molluscan contraband she'd interdicted at the port (4). I get requests of this sort all the time, and I always try to help.

So why would you Gubmint Bozos go out of your way to piss me off? It seems to me that, of all 300 million citizens in this great country of ours, the one guy whose good word you should believe, if he checked NO on the snails box of his customs declaration, would be Dr. Robert T. Dillon, Jr. I'll bet I'm the only professional malacologist in the history of USDA-APHIS form PPQ-526 who has ever endured the hassle of importing live snails properly. And for my honest efforts, you send some officious woman to rifle through my dirty underwear in Atlanta International Airport? Well, it'll be a long time before this "dialogue" opens up again.


Notes
(1) Non-pests, Non-plants, and Non-sense at the USDA [17Dec08].

(2) Hit the "Science and Public Policy" label above and to the right to review a series of posts on this recurring theme.

(3) Cowie, R. H., R. T. Dillon, D. G. Robinson and J. W. Smith (2009) Alien non-marine snails and slugs of priority quarantine importance in the United States: A preliminary risk assessment. American Malacological Bulletin 27: 113-132. [PDF]

(4) Special Agent Rebecca Roca of the USFWS sent me several photos of the "bear paw clam" Hippopus hippopus back on April 12. I had one of those photos posted below, but she asked me to remove it (without explanation) on May 19.

(5) Note added November, 2011. In subsequent correspondence with other colleagues, I have discovered that there are (almost) no reliable photos of Physa (or Aplexa, or Stenophysa) marmorata available anywhere on the web. If you google images for marmorata, you will obtain pages and pages of photos of trash Physa acuta. So here, as a service to the community at large, is a photo of a bona fide Physa (Stenophysa) marmorata individual (13.5 mm) from Ojojona, Honduras.

Goodbye Goniobasis, Farewell Elimia

Editor's Note.  This essay was subsequently published as: Dillon, R.T., Jr. (2019c) Goodbye Goniobasis, Farewell Elimia.  Pp 19-22 in The Freshwater Gastropods of North America Volume 3, Essays on the Prosobranchs.  FWGNA Press, Charleston.

The systematic relationships among Pleurocera, Goniobasis, Elimia, and several other nominal genera of slender pleurocerids in eastern North America first rose to our attention in February of 2007 (1). Faithful readers may remember the post to this blog entitled “Goodrichian Taxon Shift,” in which I reported a survey of gene frequencies in a pleurocerid population inhabiting Indian Creek, a small river in the remote southwestern corner of Virginia. The shell morphology demonstrated by that particular population varied from the slender and carinate “Goniobasis acutocarinata” form in the headwaters to the smooth and more heavily shelled Goniobasis clavaeformis form in the main creek itself. And at the mouth, where Indian Creek emptied into the Powell River, the shell morphology of this single population of pleurocerids became so chunky as to appear to change genera, to “Pleurocera unciale.”

I returned to this subject in October of 2009 under the title “Pleurocera Puzzles” (2). In that second post I reported an extension of my Indian Creek study to include pleurocerid populations inhabiting three additional subdrainages: the Pistol/Little River near Maryville (TN), the Conasauga/Hiwassee River east of Etowah (TN), and the Coahulla/Oostanaula River in North Georgia. In all four cases, the populations of Pleurocera inhabiting downstream reaches were more genetically similar to the local “Goniobasis” populations immediately upstream than to other nominal Pleurocera populations. This would seem to confirm that the shell attributes by which Pleurocera and Goniobasis have historically been distinguished cannot stand.

Taxonomic controversies have simmered within the tiny, closely knit scientific community working on the North American Pleuroceridae since the birth of American malacology. In my blog post of November 2010, I reviewed the longstanding disagreements over the generic nomina Pleurocera, Lithasia, and Oxytrema, which continued through most of the 20th century (3). More visible recently has been the controversy regarding the generic nomina Goniobasis and Elimia, which I reviewed in a blog post way back in September of 2004 (4).

We’ve been beating each other up over whether to call these populations Pleurocera, Oxytrema, Goniobasis, Elimia, and God Knows What Else for almost 200 years, and there’s never been a nickel’s worth of biological difference in the lot of them (5). Let’s put all this behind us, shall we?

The research results I telegraphed to this group in October 2009 have just been published in the issue of Malacologia currently on the newsstands. In Appendix 1 of that paper I formally synonymize Goniobasis, Elimia, and eight more obscure genera under the genus Pleurocera (Rafinesque, 1818). A pdf download is available from link (6) below. See pp 276 - 77.

The FWGNA site has been completely updated to correct all primary instances of the generic nomen “Goniobasis” to the most recent taxonomy (7). I would invite my colleagues to do likewise with the generic nomen, “Elimia.” Let the peace of Pleurocera begin.

Notes

(1) Goodrichian Taxon Shift [20Feb07].

(2) Mobile Basin III: Pleurocera Puzzles [12Oct09]

(3) Joe Morrison and the Great Pleurocera Controversy [10Nov10]

(4) Goniobasis and Elimia [28Sept04]

(5) DAZO, B.C. (1965) The morphology and natural history of Pleurocera acuta and Goniobasis livescens (Gastropoda: Cerithiacea: Pleuroceridae). Malacologia 3:1-80. STRONG, E.E. (2005) A morphological reanalysis of Pleurocera acuta Rafinesque, 1831, and Elimia livescens (Menke, 1830) (Gastropoda: Cerithioidea: Pleuroceridae). Nautilus 119:119-132.

(6) 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]

(7) I did not change the file names, only the html text. Even so, the process took several days, and I’m still not sure I've caught every instance. If you find any stray “Goniobasis” in the text of the FWGNA site, let me know.

When Art and Science Collide

Editor’s Note – This essay was subsequently published as: Dillon, R.T., Jr. (2023c)  When Art and Science Collide.  Pp 335 – 338 in The Freshwater Gastropods of North America Volume 7, Collected in Turn One, and Other Essays.  FWGNA Project, Charleston, SC.

Last fall I received an unusual email from Mr. Mark Wentzel, a sculptor living in the Atlanta area, bearing the subject line “L. columella.” Mr. Wentzel explained that he was working on an art exhibition for the Rollins School of Public Health at Emory University, and inquired whether there might be “a source for ordering Lymnaea columella shells,” or if not, advice as to “a good method (or locality) of obtaining one. I was intrigued.

Connections between the Mollusca and the visual arts have a long and lavish history. Seashells, in particular, become decorative items almost untouched by the hand of man, save for a good cleaning. Entire coffee-table books have been dedicated to seashells as adornment in the primitive peoples, seashell motifs in the works of the renaissance masters, sailor’s valentines, X-ray photographs, and so forth. Upon entering the church of St. Sulpice in Paris, one finds the holy water contained in a massive pair of Tridacna valves, gifts from Venice to Francis I. How they got to Venice in the early 16th century, God knows.

Freshwater gastropods, however, are not decorative. One could certainly fashion the image of a freshwater snail into a logo and put it on a tee shirt. But I cannot (off the top of my head) think of any works of visual art, intended to stand alone, featuring our favorite creatures.

So I struck up an email correspondence with Mr. Wentzel to learn more about his project. Fishing for a connection to public health, I asked if his interest in L. columella might be somehow tied to the potential of lymnaeids to host fascioliasis. He replied that “Fascioliasis comes into play, but mostly as a metaphor.” More directly, the work he was contemplating “involves water, a Vietnam era Mk2 hand-grenade, a four-gallon Mason, lead drinking cups, and the unfamous (sic) L. columella, an indirect nod to Lucius Junius Moderatus Columella, the Roman author of De Re Rustica, including significant early contributions to the field of food preservation.”

Mr. Wentzel added, almost as an afterthought, “My choice of L. columella was no fluke.” Okay, that got me. I sent him a sample of L. columella in the next morning’s “snail mail.”

The exhibition opened in December, under the title “4 Fields: Science and Environmental Health from a Creative Point of View.” [Click the image above to read the flyer.] I have not been to Atlanta to view the works first hand, but my overall impression, judging from the brochure, is that it is complicated. The title was “borrowed from the concept of the four sub-fields of anthropology” which turn out to be (according to Wikipedia) physical anthropology, cultural anthropology, archaeology, and linguistics. The connection between anthropology, sculpture, and environmental health is obscure to me. As well as many other things.



The figure above shows Mark Wentzel's entire work [click for enlargement]. Our Lymnaea columella shells have been given rubbery little bodies and affixed to the tip of a Pasteur-style swan-necked flask at the far left. The hand grenade appears as a spigot for the 4-gallon mason. A close-up of the most exciting part of the piece is shown below.

The next paragraph is going to be boring and obvious, but bear with me. I’m getting ready to make a point.

Art and Science are two entirely different things. Mark Wentzel works in a world with its own unique language, culture, and set of values that are entirely different from, no better and no worse than, the world in which I live. This does not mean that artists and scientists cannot work together. Our worlds are not incompatible. But neither are our worlds compatible in any sense, either. They are just completely, utterly different.

Now scratch out the word "art" in the paragraph above, an insert the phrase, “law and public policy.” The paragraph will remain just as true. Science is no more compatible with public policy than it is with fine art.

Last month I got a (rather routine) email from a DNR biologist working on a revision of the South Carolina priority conservation invertebrate species. He wanted to know what freshwater gastropods in our state might be “of conservation concern.” So I pointed him to Table 1 on the Freshwater Gastropods of South Carolina website, where all 32 of our species are ranked by their abundances at many hundred sampling sites. My own (completely subjective) opinions regarding which of those species might warrant some conservation concern are to be found under "Recommendations" on that same site.

But in a larger sense, the concept of "conservation concern” in law is no more scientific than the concept of “beauty” in the fine arts. Neither can be measured, and hence science has nothing to say about either.

I was happy to send data to our DNR biologist, just as I was happy to send Mr. Wentzel some shells of L. columella. But I would never dream of pretending that science figures into my interactions with the latter world. Why do we continue to imagine that science can enter into the former?