Dr. Rob Dillon, Coordinator





Monday, June 7, 2021

The American Galba and The French Connection

I do not understand how the United States of America, the richest nation on earth, has fallen so far behind the rest of the world in organismal biology.  Our NASA and our NIH and all those bomb factories run by the DOE are all first-rate, I feel sure.  But when it comes to the biotic majesties of our purple mountains – all the living things that creep under our rocks and crawl through our waters and crowd each other for light from one of our shining seas to the other – we are clueless as Mercedes-full of Kardashians.  Adjusted by GDP, our malacology is shamed by that of Guatemala.

The French National Centre for Scientific Research (CNRS) is the largest basic science agency in Europe, with an annual budget of 3.3 billion euros.  Prominent among their 1,100 research laboratories is the Centre for Functional Ecology and Evolutionary Biology (CEFE) in Montpellier, where a faculty and staff of 282 conduct research on exactly the kinds of scientific questions that we here in America suck at.  Help us, France, you’re our only hope.

I first met Dr. Philippe Jarne of the CEFE at the Society for the Study of Evolution in Snowbird, Utah back in 1993.  But by that point we had already been corresponding for six years.  I still have in my filing cabinet an old-fashioned letter Philippe sent me in 1987, when he was doing his PhD research on the population genetics of Lymnaea peregra [1].  His research was top notch, is top notch, and always has been top notch – using a variety of freshwater pulmonates (e.g., Bulinus, Biomphalaria, Physa) to address questions about mating systems and sex allocation of great generality and importance.  It was Philippe who sent Amy Wethington and me our sample of Physa acuta from France back in 2000 [2].  And I sent him a sample of Lymnaea (Galba) cubensis from here in the Charleston area in 2009, a sample which ultimately played some small role in a paper he and the Montpellier research group published in 2011 [3].

Below is a photo that my daughter snapped at a lunch we enjoyed in Montpellier back in March of 2012, with (from my left) myself, Philippe Jarne, Patrice David, my lovely wife Shary and my French son-in-law Eric.

So on 8Apr15 Philippe emailed me to propose a new collaboration, to “estimate the selfing rate in as many species (of basommatophoran pulmonates) as possible” using a molecular method called RAD-SEQ [4].  Philippe, Tom Janicke, and their collaborators needed about 50 individuals per population from as diverse and as widespread a sample of pulmonates as possible worldwide, the idea being to correlate selfing rates with inbreeding depression.  I told him that I would be happy to help.  I logged many thousand miles on that project through the spring and summer of 2015, covering ten states, ultimately collecting N>50 individuals from 44 populations of 17 pulmonate species [5].  That research effort did not yield results.

I was disappointed by the failure of the Janicke/Jarne project, of course, and I confess, a little bit sore.  But thank heaven, at the opening of the initiative I was able to negotiate along a related line of research that ultimately did yield publishable results, which have now cast considerable light into one of the darker corners of North American freshwater malacology, those crappy little amphibious lymnaeids we here often called “Fossaria,” but which the rest of the world usually calls Galba [6].

In my enthusiastic reply of 8Apr15 I referenced Lymnaea (Galba) humilis, which I offered as a perfect example of North American ignorance regarding pulmonate self-fertilization.  Philippe then let it drop in his follow-up of 10Apr15 that “a PhD student under the supervision of S. Hurtrez here in Montpellier” (who turned out to be Pilar Alda) was even at that date working on “these small Lymnaea, including the infamous schirazensis.”  And so in an email of 13April15, I seized the opportunity to “brainstorm on a tangent.”

The Alda/Hurtrez project to which Philippe was referring was an extension of the 2011 research I mentioned five paragraphs above [3], focused on the Galba of medical and veterinary importance, primarily sampled from South and Central America and the Caribbean.  So I suggested an expansion through North America to include humilis and all the taxa that Hubendick [7] thought synonymous under humilis, but that Burch [8], following Baker [9], had considered separate.  In addition to collecting humilis/modicella from its type locality in New York, I volunteered to collect obrussa from its type locality in Philadelphia, parva from its type locality in Cincinnati, exigua from its type locality in Tennessee, and similar-looking crappy-little amphibious lymnaeid populations from a broad swath of additional muddy riverbanks across the eastern USA.  And on 5May15, Philippe, together with his colleagues Patrice David and Sylvie Hurtrez, agreed.

L. humilis on the margins of Lake Pymatuning, PA

The results of that research have just been published in the April issue of Molecular Phylogenetics and Evolution – a massive work involving 161 populations of Galba and almost as many coauthors [10].  But before I review our findings, I feel as though I should back up and introduce, or in some cases re-introduce, a cast of amphibious little crap-brown snails that has now grown worldwide in scope.  Most of the specific nomina that have been assigned to the lymnaeid subgenus Galba over the last 200 years will be unfamiliar to my North American readership.  Quite a few of those unfamiliar names will, however, become important in the essay I am planning to post next month.

Buccinum truncatulum was described by O.F. Müller in 1774 from Thangelstedt, a village in central Germany.  Populations of Muller’s crappy-little amphibious lymnaeid, which we now classify as Lymnaea (Galba) truncatula, are native to the muddy margins of ponds, rivers, and lakes across Northern Europe and Asia, reportedly extending over the Bering Land Bridge to Alaska, Yukon, and British Columbia.  The species also seems to have been introduced to South America, currently ranging from Chile through Brazil and Peru to Venezuela.  Lymnaea (Galba) truncatula serves as the intermediate host of the sheep liver fluke, Fasciola, and has been the focus of a great deal of research interest, for many years.  The first-marginal teeth on their radular ribbons bear three cusps.  Reproduction is primarily by self-fertilization [11].

The second crappy-little amphibious lymnaeid to reach description worldwide was our own Lymnaeus humilis, authored by Thomas Say (1822).  Populations of L. humilis inhabit the same sorts of marginal habitats as Old World L. truncatula, ranging throughout the United States and Canada.  I was first drawn into the bigtime world of international Galba research in early 2008, when Prof. Dr. Santiago (“Santi”) Mas-Coma of the University of Valencia contacted me about collecting some L. humilis from their type locality here in South Carolina.  Santi and his wife, Maria Dolores Bargues, together with many collaborators, had even by that early date published over 20 papers on fascioliasis and its gastropod vectors worldwide.

Thomas Say did, indeed, receive samples of crappy-little amphibious lymnaeids from the Charleston area in the early nineteenth century, and it does indeed seem likely that samples from Sullivan’s Island (at the mouth of Charleston Harbor) were before him when he described his Lymnaeus humilis.  But it turns out that all our crappy-little amphibious lymnaeids here in the Charleston area have bicuspid first lateral radular teeth, rather than tricuspid, and would today conventionally be identified as Lymnaea cubensis.  So since Say also mentioned “a variety of” his L. humilis at “Oswego” (Owego), New York, I suggested in an essay published on this blog in the summer of 2008 that Say’s humilis type locality be restricted to New York, where the crappy-little amphibious lymnaeid populations are tricuspid [12].

From Bargues et al [13]
Shortly after posting that 2008 essay I drove up to Owego, collected a topotypic batch of L. humilis, and packed them off to my buddy Santi Mas-Coma. The Valencia group then sequenced five DNA markers (CO1, 16S, 18S, ITS-1 and ITS-2) for eight of the snails I collected at that type locality, plus six cubensis individuals I collected from the Charleston area, and developed a manuscript [13], which was never published [14], which was even at that early date becoming a theme of my experience with European research groups.

But let’s back up a couple hundred years and get a fresh start at our historical narrative.  In 1825 Thomas Say redescribed the “Oswego” population as “Lymnaeus modicelles,” and added obrussa from Philadelphia and the subfossil galbana from New Jersey.  Baker [9] respelled that first nomen “modicella” and shifted it to subspecific status under humilis.

Five years later, way down south, Captain P. P. King [16] described Limnaea diaphana from collections made in the Straits of Magellan area, on the first voyage of The Beagle.  That little snail bears a shell indistinguishable from truncatula and humilis, according to Hubendick [7] and Paraense [17].  But the sequence data seem to suggest that L. diaphana is not a Galba, but rather an “archaic relict” stagnicoline [18].  So, let’s set King’s nomen aside.

The next name published in the worldwide literature of crappy-little amphibious lymnaeids was Lymnoeus viator, described by d’Orbigny in 1835 from two places simultaneously, Patagonia (exact locality unspecified) and Peru (Lima), subsequently restricted to the Negro River at Viedma, Argentina by Paraense [19].  Very similar biologically to all the other lymnaeid populations we have reviewed in this essay, the nominal range of L. viator (as conventionally understood) ranges across the bottom of South America from Chile through Argentina to Uruguay. This seems to be the oldest name [20] attached to any population of the subgenus Galba bearing bicuspid first marginal teeth on the radula.  Populations of L. viator can also serve as the hosts of Fasciola which, in some parts of the New World at least, can infect humans as well as livestock.

Shortly thereafter Pfeiffer (1839) described Limnaea cubensis from Cuba, exact locality unspecified.  Populations of this nominal species are conventionally considered to range across the entirety of South and Central America and the Caribbean, overlapping with L. viator in the south, extending into the southern United States, as touched upon five paragraphs above.  Lymnaea (Galba) cubensis is the most important intermediate host of Fasciola in the New World.  Reproduction seems almost exclusively by self-fertilization [11].  The essay I wrote reviewing Charleston-area lymnaeid populations back in 2008 featured a history of L. cubensis, both natural and otherwise, figuring shell and bicuspid radula [12], if you’re hungry for more.

So welcome back to the USA.  In 1841 our old buddy Isaac Lea [21] described Lymnaea parva from Ohio (Cincinnati), L. rustica from Ohio (Poland), L. exigua from Tennessee (unspecified) and L. bulimoides from Oregon (unspecified).  The first three bear three cusps on their first marginal radular teeth and are indistinguishable from humilis in all respects.  But Lea’s nomen bulimoides seems to be the oldest name homegrown here in the USA for crappy little amphibious lymnaeids that have turned out to bear bicuspid first laterals.
From Fig 3 of Correa et al [3]

The dawn of the 20th century saw an explosion of taxonomic activity in the American Lymnaeidae, with Pilsbry, Dall, Baker and Walker adding dozens of nomina, including perpolita, cockerelli, sonomaensis, dalli, cyclostoma, peninsulae, hendersoni, alberta, perplexa, and vancouverensis.  Baker’s (1911) review listed 30 species and subspecies of crappy-little amphibious lymnaeids from North and Middle America,  which he accumulated into Shrank’s (1803) large and inclusive genus Galba [9].  In 1928 Baker [22] split the littlest Galbas into Fossaria (Westerlund 1885), which he divided into tricuspid and bicuspid subgenera, the system essentially adopted by Burch [8].

Back to the Old World one last time, we cannot overlook, as many subsequent authorities most certainly have, Limnaeus schirazensis, described by Küster in 1862 from Shiraz, Iran.  The “infamous” schirazensis, as Philippe termed it, was resurrected in 2011 by Maria Bargues, Santi Mas-Coma, and their coauthors [23] on the basis of DNA sequence distinctions at 18S, ITS-1, ITS-2, 16S and CO1.  Our good friends in Valencia identified schirazensis populations inhabiting eight countries: Iran, Egypt, Spain, Mexico, Venezuela, Ecuador, Peru, and The Dominican Republic, the last five presumably resulting from artificial introduction.

Lymnaea schirazensis populations seem to reproduce almost exclusively by self-fertilization [11].  In habitat, the Valencia group noted that they seem to demonstrate an unusual preference for the land-side of amphibious over the water-side of amphibious.  The situation with the first marginal radular teeth also seems peculiar, “usually bicuspid” but with a “faint tendency” to appear tricuspid in some populations.  And most importantly, from a human standpoint, populations of L. schirazensis are apparently entirely refractory to Fasciola infection.  The Valencia group concluded by suggesting that confusion between refractory schirazensis and susceptible populations of truncatula, cubensis, and viator might have “distorted” data on the incidence of fascioliasis worldwide.

While Küster’s nomen schirazensis was being merely forgotten, Limnaea pictonica, described from Tierra Del Fuego by Rochebraune & Mabille in 1885, was being really most sincerely forgotten [24].  But continuing on to the present day is Jousseaume’s Limnaea cousini, proposed in 1887 to describe a population of crappy-little amphibious lymnaeids in Quito, Ecuador.  Populations of Lymnaea (Galba) cousini bear shells with an unusually-large body whorl and are not generally considered “cryptic” underneath the other crappy-little amphibious lymnaeid populations of South America.  They are also unusual in that they seem to reproduce primarily by outcrossing.  Their radular ribbons demonstrate tricuspid first laterals.  For morphology see Paraense [25], for genetics ask our friends in Valencia [26].

Detail from Baker [8] Plate VII

There were also a bunch of 20th-century nomina proposed by Pilsbry and colleagues for South American populations of crappy-little amphibious lymnaeids that I am simply not going to mention, synonymized by Hubendick [7], rest in peace, all of them.  Two more recently-described South American taxa, neotropica [27] from Lima, Peru and meridensis [26] from Merida State, Venezuela will however play minor rolls in our review next month.

In 1951 Bengt Hubendick, bless his heart, tried to impose some modern order upon this classical mess, lowering hundreds of lymnaeid nomina into synonymy worldwide [7].  In addition to the Holarctic truncatula he recognized humilis, cubensis, and bulimoides from North and Middle America, plus viator, pictonica and cousini from South America, for a total worldwide fauna of seven species of crappy-little amphibious lymnaeids that anybody today might assign to Galba.  And it was Hubendick’s clean, simple model that the FWGNA project adopted in [28Dec06].

Alas, Hubendick’s signal contribution to our understanding of the worldwide Lymnaeidae has been widely ignored.  Burch [8] advocated a seven-species, ten-subspecies, two-subgenus model for North American “Fossaria” based on the work of F. C. Baker [9, 22], and it has been under the Baker/Burch model that most of the USA has labored for 40 years.

Until now, with the help of our French brethren across the seas.  “Le bonheur de l'Amérique est intimement lié au bonheur de toute l'humanité [28].”  Tune in next time.


Notes:

[1] More recently many of our colleagues in Europe have begun referring to Lymnaea peregra as “Radix balthica.”  That the malacofauna of Europe is better known than ours here in North America does not imply that their taxonomy is more stable.  Just exactly the opposite.

[2] Dillon, R. T., A. R. Wethington, J. M. Rhett and T. P. Smith.  (2002)  Populations of the European freshwater pulmonate Physa acuta are not reproductively isolated from American Physa heterostropha or Physa integra.  Invertebrate Biology 121: 226-234.  [PDF]  For more, see:

  • To Identify a Physa, 2000 [6Dec18]

[3] Correa, A.C., J.S. Escobar, O. Noya, L.E. Velasquez, C. Gonzalez-Ramirez, S. Hurtrez-Bousses & J-P. Pointier (2011)  Morphological and molecular characterization of Neotropic Lymnaeidae (Gastropoda: Lymnaeoidea), vectors of fasciolosis.  Infection, Genetics and Evolution 11: 1978-1988.  For a review, see:

  • The Lymnaeidae 2012: Fossarine Football [7Aug12

[4] Rubin, B.E.R., R.H. Ree, and C.S. Moreau (2012)  Inferring phylogenies from RAD sequence data.  Plos One 7(4): e33394. 

[5] Not including Physa acuta!  No audience better than you, the faithful readership of my footnotes, are equipped to appreciate what a challenge it was to collect N>50 individuals from 44 populations of pulmonate snails across 10 American states, representing 17 species, not to include Physa acuta.  And to understand my frustration when that effort yielded nothing, not even an oral presentation, not even an acknowledgment.  So you want to be a scientist, kid? 

[6] The FWGNA Project has adopted the “Hubendick compromise” model for the classification of the Lymnaeidae, recognizing Galba as a subgenus of the worldwide genus Lymnaea [7].  In the series of essays that follows we will often, however, refer to the nomen Galba as though it were a genus, following the usage of the authors whose work we are reviewing.  See:

  • The Legacy of Frank Collins Baker [20Nov06]
  • The Classification of the Lymnaeidae [28Dec06]

[7] Hubendick, B. (1951)  Recent Lymnaeidae.  Their variation, morphology, taxonomy, nomenclature and distribution.  Kungliga Svenska Vetenskapsakademiens Handlingar Fjarde Serien 3: 1 - 223.

[8] 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).

[9] Baker, F. C. (1911) The Lymnaeidae of North and Middle America, Recent and Fossil. Special Publication, no. 3. Chicago: Chicago Academy of Natural Sciences.

[10] Alda, Pilar, M. Lounnas, A.Vázquez, R. Ayaqui, M. Calvopiña, M. Celi-Erazo, R.T. Dillon Jr., L. González Ramírez,  E. Loker, J. Muzzio-Aroca, A. Nárvaez, O. Noya, A. Pereira, L. Robles, R. Rodríguez-Hidalgo, N. Uribe, P. David, P. Jarne, J-P. Pointier, & S. Hurtrez-Boussès (2021) Systematics and geographical distribution of Galba species, a group of cryptic and world-wide freshwater snails.  Molecular Phylogenetics and Evolution 157: 107035. [pdf] [html]

[11] I am currently drafting a separate essay on the subject of asexual reproduction in crappy-little amphibious lymnaeids of the subgenus Galba, to be posted in the near future.  For now, here are the key references:  Trouvé, S. et al. (2000) Microsatellites in the hermaphroditic snail, Lymnaea truncatula, intermediate host of the liver fluke, Fasciola hepatica. Molecular Ecology 9(10): 1662–1664.  Trouvé, S. et al. (2003)  Evolutionary implications of a high selfing rate in the freshwater snail Lymnaea truncatula.  Evolution 57: 2303 – 2314.  Meunier C. et al. (2004)  Field and experimental evidence of preferential selfing in the freshwater mollusc Lymnaea truncatula (Gastropoda, Pulmonata).  Heredity 9: 316 – 322.  Lounnas, M. et al. (2017) Isolation, characterization and population-genetic analysis of microsatellite loci in the freshwater snail Galba cubensis (Lymnaeidae). J. Molluscan Stud. 83: 63–68.  Lounnas, M. et al. (2018) Population structure and genetic diversity in the invasive freshwater snail Galba schirazensis (Lymnaeidae). Can. J. Zool. 96: 425–435.

[12] For a detailed review of the cubensis/humilis situation here in the Charleston area, with notes on morphology and natural history, see:

  • Malacological Mysteries I: The type locality of Lymnaea humilis [25June08]

[13] Bargues, M.D., P. Artigas, R.T. Dillon, Jr., and S. Mas-Coma (unpubl) Fascioliasis in North America: Multigenic characterization of a major vector and evaluation of the usefulness of rDNA and mtDNA markers for lymnaeids.

[14] Here’s a quote from a Mas-Coma email of 26may11: “You cannot imagine the problems originated by your sending of L. cubensis from Sullivan island to the French Jean- Pierre Pointier!!! He did publish his results before we did! […] They even used our sequences of L. humilis taken from GenBank even if we did not yet publish them. And of course they never mention that these sequences are ours, but write the article in a manner [15] that the reader believes that these sequences were made by them!!”

[15] To be fair.  Correa, Hurtrez-Boussès, Pointier and the Montpellier group did cite the GenBank accession numbers for our humilis sequences from Owego, which if one refers to GenBank, are attributed to Bargues/Mas-Coma.  It is my impression that this is a general problem with the GenBank system – secondary researchers mining and publishing research based on sequences which the primary authors may not have as yet published.

[16] King, P.P. (1830) Description of the Cirripeda, Conchifera and Mollusca in a collection formed by the Officers of the HMS Adventure and Beagle employed between the years 1826 and 1830 in surveying the southern coasts of South America, including the Straits of Magalhaens and the Coast of Tierra del Fuego Zoological Journal 5, Article 47: 332- 349.

[17] Paraense WL 1984. Lymnaea diaphana: a study of topotypic specimens (Pulmonata: Lymnaeidae). Mem Inst Oswaldo Cruz 79: 75-81.

[18] Bargues, M.D., R. L.M. Sierra, P. Artigas, and S. Mas-Coma (2012)  DNA multigene sequencing of topotypic specimens of the fascioliasis vector Lymnaea diaphana and phylogenetic analysis of the genus Pectinidens (Gastropoda).  Mem Inst Oswaldo Cruz 107: 111 – 124.

[19] Paraense, W.L. (1976)  Lymnaea viatrix: a study of topotypic specimens.  Rev. Brasil. Biol. 36: 419 - 428.

[20] Paraense suggested that d’Orbigny’s 1835 nomen be respelled as “viatrix” to agree in gender with the feminine “Lymnaea.”  In March of 2019 I asked our good friend Harry Lee for a ruling on this usage.  Harry replied that d’Orbigny’s specific epithet is not an adjective, rather “it is clear from the Latin (and French; see d'Orbigny, 1837: 340) that ‘viator’ is an appositive (an unambiguous noun; like viatrix) and should not be declined to agree with the gender of any combining generic epithet.”  Harry concluded that Paraense’s respelling is an “unjustified emendation in the language of the Code, and an unavailable name under its provisions. By coincidence, I think the same relationship holds for Lymnaea and Lymnoeus!”

[21] Lea, Isaac (1841) On fresh water and land shells.  Proceedings of the American Philosophical Society 2: 30 – 34.  Proc. Amer. Philos. Soc. II, 30 – 34.

[22] Baker, F.C. (1928)  The Fresh Water Mollusca of Wisconsin, Part I, Gastropoda.  Bulletin 70 of the Wisconsin Geological and Natural History Survey.  507 pp.

[23] Bargues, M.D., P. Artigas, M. Khoubbane, R. Flores, P. Glöer, R. Rojas-Garcia, K. Ashrafi, G. Falkner, and S. Mas-Coma (2011)  Lymnaea schirazensis, an overlooked snail distorting fascioliasis data: Genotype, phenotype, ecology, worldwide spread, susceptibility, applicability.  Plos One 6 (9): e24567.

[24] Lymnaea pictonica (Rochebraune & Mabille 1885) may be a synonym of L. diaphana.  See Bargues et al. (2012) from note [18].

[25] Paraense W.L. 1995. Lymnaea cousini Jousseaume, 1887, from Ecuador (Gastropoda: Lymnaeidae). Mem Inst Oswaldo Cruz 90: 605-609.

[26] Bargues, M.D., Artigas, P., Khoubbane, M., Mas-Coma, S., 2011. DNA sequence characterisation and phylogeography of Lymnaea cousini and related species, vectors of fascioliasis in northern Andean countries, with description of L. meridensis n. sp. (Gastropoda: Lymnaeidae). Parasites & Vectors. 4 (132).

[27] Bargues, M.D., Artigas, P., Mera y Sierra, R., Pointier, J.-P., Mas-Coma, S., 2007. Characterisation of Lymnaea cubensis, L. viatrix and L. neotropica n. sp., the main vectors of Fasciola hepatica in Latin America, by analysis of their ribosomal and mitochondrial DNA. Ann. Tropical Med. Parasitology 101:621–641.

[28] Usually translated as, “The good fortune of America is closely tied to the good fortune of all humanity.”  From a letter written home by the Marquis de Lafayette, as he sailed toward blockaded Charleston in 1777.

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