Dr. Rob Dillon, Coordinator

Monday, April 5, 2021

Bill and Ruth and Jack and Virginia, and Campeloma

Bill Clench was already well into the mascot phase of his career when I first met him at the 1976 AMU meeting in Columbus, Ohio.  Colleagues, students, and friends ushered him front-row-center for the annual society photo, Joe Morrison [1] and Leslie Hubricht [2] trailing in his wake.  I found Dr. Clench to be a warm and outgoing gentleman, still alert at age 78.  Please Lord, take me home before anybody calls me “alert.”

William J. Clench was born in New York in 1897 and grew up in the Boston area, collecting bugs, snails and shells around the Fenway, the Blue Hills and the local beaches [3].  Charles W. Johnson, the noted marine malacologist at the Boston Society of Natural History, was an early influence.  Clench graduated from Michigan State University in 1921, earned his MS at Harvard in 1923, then moved on to the University of Michigan to work on his doctorate [4], where Bryant Walker, quoting Tucker Abbott’s remembrance [5], “lit the malacological fires within Bill and was largely responsible for his first love, the freshwater mollusks.”

American Malacological Union 1976 [6]

From Michigan Clench accepted the mollusk curatorship at Harvard’s Museum of Comparative Zoology, where he served for 40 years, 1926 – 1966, mentoring many students who would become quite influential themselves.  Clench’s most famous student was R. Tucker Abbott, who succeeded Henry Pilsbry as curator at the ANSP and editor of The Nautilus, but we should not fail to mention the unionid guys Dick Johnson and Sam Fuller, or Arthur Clarke, whose landmark work on the Canadian freshwater molluscan fauna [7] sits handy by my desk, here 40 years after its publication.

Clench’s bibliography lists 420 scientific papers, covering the breadth of malacology: marine, terrestrial, freshwater and fossil, focused on North America but ultimately worldwide [8].  Most of his better papers were coauthored by Ruth Turner, another former student, with whom Clench’s life was “entwined,” to borrow Dick Johnson’s carefully-chosen verb.  We have previously featured on this blog the 1956 Clench and Turner monograph on the freshwater mollusks of Florida/Georgia Gulf drainages [9], which was an important contribution.

Clench’s malacology was early-modern, rooted in the old typology but with a growing appreciation of genetic variation within and among populations.  Looking down from my 2021 freshwater-gastropod-centric perspective, his greatest contribution was his two-part series on the North American Viviparidae, published in 1962 [10] and (with Sam Fuller) in 1965 [11].

The taxonomic history of the North American Viviparidae is identical to the taxonomic history of the North American Pleuroceridae, minus one order of magnitude coming into the 20th century, and two going out [12].  Digging through the musty tomes on the shelves and the dusty shells in the cabinets of the MCZ in the early 1960s, Clench was able to uncover 49 Latin nomina assigned to the genus Campeloma, Isaac Lea [14] tying C.S. Rafinesque for the lead with six each.  Of those 49 nomina, 35 he discarded for cause or synonymized, little rationale given or expected, at the close of the era when such good works were still possible.  Clench did not preface his work with an exhaustive study of shell morphological variation, as did my hero Calvin Goodrich for the North American pleurocerids in the 1940s [15].  But I don’t think he missed any viviparid nomina either, as Goodrich simply skipped hundreds of pleurocerids.  I think Clench got them all.  Thank you, Bill.

Alas, Clench did not explain why he spared the 14 specific Campeloma nomina that survived his 1962 monograph, any more than he explained why he cut the other 35.  That burden was shouldered 20 years later by Dr. John B. Burch [16], with an obscure contribution from Dr. Virginia A. Vail.

From the Burch/Vail key [16]

The “Family Viviparidae” header in Burch’s dichotomous key, way back on page 227, carries an asterisk.  And at the bottom of page 227 is printed, “*From Burch & Vail (1982).”  But no work by Burch & Vail is listed among the references, nor was one ever published subsequently, to my knowledge [17].

Burch’s bibliography does, however, list six papers published by Virginia Vail at that point in her career, all solo, and they are good ones.  She was an excellent scientist, about whom I have been able to discover little.  She was born in Schenectady, NY, in 1945, earned her B.A. at Hartwick College (NY) and her M.S. and Ph.D. at Florida State University, graduating in 1975 [18].  From thence Vail went directly to the Tall Timbers Research Station north of Tallahassee, where she spent the rest of her career.

In 1977 and 1978 Virginia Vail published a two-part series comparing the reproductive anatomy and life history of Campeloma, Lioplax, and Viviparus in Florida.  Her first paper [19] was anatomical, featuring very nice drawings of male and female reproductive systems for all three taxa, and her second paper [20] ecological, detailing seasonal reproductive cycles.  The viviparids are quite conservative anatomically; Virginia was able to document only negligible difference in the plumbing of the three genera [21].  But here 40 years later, we still await a finer contribution to the comparative biology of the North American Viviparidae.

Virginia Vail identified the Campeloma population she selected for her study as C. geniculum (Conrad).  Interestingly, that particular population, inhabiting the Chipola River about 60 miles NW of Tallahassee, seems to have been entirely sexual, males and females (apparently) in roughly equal proportion.  She made only passing reference to asexual reproduction in her 1977-78 papers, noting that Mattox [23] had documented parthenogenesis in Campeloma rufum [24] as early as 1937.

Vail [19] figs. 5 & 10 [25]

The next year, Vail described Campeloma parthenum from Lake Talquin, an impoundment of the Ochlockonee River west of Tallahassee.  She distinguished that population both by its apparent absence of males and by the contour of the outer lip of the shell [26].  But she seems to have been struggling with species concepts, even as she was describing new ones.  Here is the title and abstract of the talk she gave at the August 1979 meeting of the American Malacological Union in Corpus Christie, TX:


A poor understanding of environmentally induced shell variation, anatomical characteristics and the animal’s biology makes species identification difficult.  The occurrence of both dioecious and parthenogenetic populations (races? species?) and their peculiar geographic distributions further complicate the problem.  Observations on southeastern populations are offered to illustrate the problem and suggest solutions.”

I could not have said that better myself.  Fascinatingly, this was neither the title nor the abstract ultimately published in the Bulletin of the American Malacological Union for 1979, page 67.  The version that saw print was much more tamely entitled, “The Species Problem in Campeloma,” and featured a relatively measured critique of reliance on shell character, noting “the fact that reproduction can occur either parthenogenetically or sexually.”  As of the publication of her 1979 abstract, Virginia Vail was only counting two Campeloma species in Florida and Georgia combined, C. geniculum and “C. limum (includes C. floridense).”

I seem to remember [27], here 40 years later, that the solution Virginia Vail suggested on that August morning at La Quinta Royale Hotel in Corpus Christie, TX, recognized just those two species, a heavily-shelled C. geniculum (sexual) and more lightly-shelled C. limum (parthenogenetic).  That was certainly the direction Fred Thompson was tending by the 1990s with his “Identification Manual for The Freshwater Snails of Florida [30].”  Thompson listed four Campeloma species for The Sunshine State (geniculum, limum, floridense and parthenum), but observed, “in view of the inconsistency of shell characters, these last three forms may represent only a single species, Campeloma limum.”

American Malacological Union 1979

But returning to the thread of our story.  It was sometime during the late 1970s that Jack Burch signed a contract with the EPA to deliver his illustrated key to the North American Freshwater Snails [16].  And somehow [31] he linked up with Virginia Vail, during the full flower of her career.

The Burch/Vail key to the North American Viviparidae that ultimately saw publication in 1982 proceeds unremarkably through its first ten couplets, guiding us to the genus Campeloma on page 228, where we are referred to supplemental note (4).  That endnote – on page 268 now – begins with a brief review of Clench’s signal (1962) contributions to our understanding of the genus Campeloma [10].  Then four more nomina are subtracted from Clench’s list of 14 species on the authority of Arthur Clarke [32]: leptum Mattox 1940, tannum Mattox 1940, integra (Say 1821) and milesi (Lea 1863).  That brought our continental fauna down to 10.

Returning to the main key, on page 229, we find an earnest effort to distinguish, by shell morphology alone, eight species of Campeloma.  Three of the ten species surviving Burch’s endnote (4) did not survive the perilous transfer forward from page 268 to page 229.  The specific nomina brevispirum (Baker 1928), exilis (Anthony 1860), and gibba (Currier 1867) seem to have vanished [33].  But one brand new species of Campeloma was added, Vail’s [26] parthenum, bringing our total continental Campeloma fauna to N = 8 canonical species, as of 1982.  In the order of their description:

  • Limnaea decisa Say 1817.  Clench speculated “Delaware River?”
  • Campeloma crassula Rafinesque 1819.  The Ohio.
  • Paludina genicula Conrad 1834.  Flint River, GA.
  • Paludina regularis Lea 1841. Coosa R, AL.
  • Paludina lima Anthony 1860. South Carolina.
  • Melantho decampi Binney 1865. Decatur, AL. [34]
  • Campeloma floridense Call 1886.  Wekiva River, FL.
  • Campeloma parthenum Vail 1979.  Lake Talquin, FL.

The Burch/Vail key to the Campeloma begins with aperture color (white vs brown), then moves on to shell shoulders (angled vs rounded) then moves on to shell profile (broadly ovate vs narrowly ovate), and so forth.  It is a valiant effort, and I do not mean to diminish the contribution of its authors.  Just the opposite.

Science is the construction of testable hypotheses about the natural world.  It is not about being right, it is about being testable.  The Burch/Vail dichotomous key to distinguish the eight canonical species of North American Campeloma is science.

Next month, we test it.


[1] For my remembrance of J.P.E. Morrison, see:

  • Joe Morrison and the Great Pleurocera Controversy [10Nov10]

[2] For a bit more about Leslie Hubricht, see:

  • The Most Cryptic Freshwater Gastropod in the World [6Aug17]

[3] Most of the biographical details relayed above were gleaned from: Turner, R. D. (1985)  William J. Clench October 24, 1897 – February 22, 1984.  Malacological Review 18: 123-124.

[4] Surprisingly, Clench did not finish.  He was ultimately awarded honorary doctorates from both Michigan and MSU in 1953.

[5] Abbott RT (1984). "A Farewell to Bill Clench". The Nautilus 98 (2): 55–58.

[6] This is a detail from a scan of the original 8x10 glossy in my files.  The back is stamped, “Dept. of Photography & Cinema, The Ohio State University,  No. 191231-1, Please Give Credit”  Done.

[7] Clarke, A.H. (1981) The Freshwater Mollusks of Canada. Ottawa: The National Museums of Canada.

[8] Johnson, R.I. (2003)  Molluscan taxa and bibliographies of William James Clench and Ruth Dixon Turner.  Bulletin of the Museum of Comparative Zoology at Harvard College 158: 1- 46.

[9] Clench, W.J. & R.D. Turner (1956)  Freshwater mollusks of Alabama, Georgia, and Florida from the Escambia to the Suwannee River. Bull. Fla. State Mus. (Biol. Sci.), 1: 97-239.   For more, see:

  • Fred Thompson, Steve Chambers, and the pleurocerids of Florida [15Feb17]

[10] Clench, W.J. (1962) A catalogue of the Viviparidae of North America with notes on the distribution of Viviparus georgianus Lea. Occasional Papers on Mollusks 2(27): 261-287.

[11] Clench, W.J. & S.L.H. Fuller (1965) The genus Viviparus (Viviparidae) in North America. Occasional Papers on Mollusks 2(32): 385-412.

[12] Graf [13] has catalogued “nearly 1,000” specific nomina historically applied to North American freshwater gastropods of the family Pleuroceridae.  Between 1934 – 1944 my hero Cavin Goodrich was able to pare these down to approximately 150.  For more, see:

  • The Legacy of Calvin Goodrich [23Jan07]

[13] Graf, D. L. (2001) The cleansing of the Augean Stables, or a lexicon of the nominal species of the Pleuroceridae (Gastropoda: Prosobranchia) of recent North America, north of Mexico. Walkerana 12 (27) 1 - 124.

[14] For more about the “Nestor of American Naturalists,” see:

  • Isaac Lea Drives Me Nuts [5Nov19]

[15] For the further exploits of my hero, see:

  • Goodrichian Taxon Shift [20Feb07]
  • Mobile Basin II: Leptoxis Lessons [15Sept09]
  • CPP Diary: The Spurious Lithasia of Caney Fork [4Sept19]

[16] 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).

[17] The parallel between the careers of Virginia Vail and George Te is inescapable here.  George Te was a Burch student in the late 1970s and seems to have ghost-written Burch’s entire treatment of the Physidae, as Virginia Vail ghost-wrote the Viviparidae.  For more on George Te, see:

  • To Identify a Physa, 1975 [6May14]
  • To Identify a Physa, 1978 [12June14]

[18] Abbott, R.T. (1975)  American Malacologists, Supplement.  American Malacologists, Greenville, Delaware. 

[19] Vail, V.A. (1977)  Comparative reproductive anatomy of 3 viviparid gastropods.  Malacologia 5: 519 – 540.

[20] Vail, V.A. (1978)  Seasonal reproductive patterns in 3 viviparid gastropods.  Malacologia 6: 73 – 97.

[21]  The viviparids have evolved [22] quite a few unique adaptations that separate them from all other living gastropods, including a weird operculum and even weirder radula.  The right tentacle of the male has been modified into a simple, external penis and the pallial gonoduct of the female modified into a marsupium, capable of nursing fertilized eggs until their hatch into impressively large crawl-away juveniles.  But within the family, their anatomy is as boringly uniform as the pleurocerids.  You crack a Viviparus shell, or a Lioplax shell, or a Campeloma shell, and look inside, and it’s basically viviparid guts.  Every time.

[22] “Retained” might be a better verb here.  The worldwide family Viviparidae seems to be ancient.  They share their peculiar concentric operculum with the Ampullaridae, which suggests that the two families are sisters.  But the viviparids have absolutely no living marine antecedents.  I take this as evidence of an hypothesis I advanced back in 2009, that evolution is slower in fresh waters than in the marine environments from which all life originated.  Like the pleurocerids, the viviparids are “living fossils.”  For more, see:

  • The snails the dinosaurs saw [16Mar09]

[23] Mattox, N.T. (1937) Oogenesis of Campeloma rufum, a partheogenetic snail.  Zeitschrift fur Zellforschung und Mikroskopische Anatomie 27: 455 – 464.

Mattox, N.T. (1938)  Morphology of Campeloma rufum, a parthenogenetic snail.  Journal of Morphology 62: 243-261.

[24] Mattox sampled his study population from a tributary of the Wabash River in eastern Illinois.  Clench [10] subsequently synonymized Campeloma rufum under C. crassulum (Raf.) 

[25] Abbreviations from Vail [19] figures 5 and 10: AG = albumin gland, CM = columellar muscle, DG = digestive gland, M = mantle, O = ovary, OD = oviduct, PMC = posterior end mantle cavity, PO = pallial oviduct, PR = prostate gland, RT = right tentacle, SR = seminal receptacle, SV = seminal vesicle, T = testis, V = vagina, VD = vas deferens,  VD’ = pallial vas deferens.

[26] Vail, V.A. (1979) Campeloma parthenum (Gastropoda: Viviparidae), a new species from north Florida.  Malac. Rev. 12:85-86. 

[27]  Isn’t it interesting the way we can remember small vignettes from 40 years ago, but cannot remember what we had for supper last night [28]?  Virginia Vail gave her talk in the freshwater session of the Corpus Christie AMU meeting at 11:00 Thursday morning, August 9, 1979.  Young Rob Dillon, then listed as a graduate student at the University of Pennsylvania, gave his talk at 11:15, “The Goniobasis of southern Virginia and northwestern North Carolina: Electrophoretic and shell morphological relationships [29].”  At approximately 11:31, Old Joe Morrison jumped up and lectured me with great passion about obscure details of pleurocerid taxonomy and systematics.  At about 11:35, I said, “Easy, big fella.”  For more, see:

  • Joe Morrison and The Great Pleurocera controversy [10Nov10]

[28] It was a chicken casserole, with cashews sprinkled on top.  I just looked in the refrigerator.

[29] That was just the second presentation I had ever made at a national meeting.  The research was ultimately published as: Dillon, R.T., Jr and G.M. Davis (1980) The Goniobasis of southern Virginia and northwestern North Carolina: Genetic and shell morphometric relationships. Malacologia 20: 83-98. [PDF]

[30] Thompson, F.G. (2000)  An identification manual for the freshwater snails of Florida.  Walkerana 10(23): 1 -96.  Also available online [html].

[31] No, it was not at an AMU meeting.  Jack Burch was never a member of the AMU/AMS during his entire professional career, as far as I know, until being elected an honorary life member in 2009.  His election was not unanimous.

[32] Clarke, A.H. (1973) The freshwater mollusks of the Canadian Interior Basin.  Malacologia 13: 1 – 509.

[33] The nomina brevispirum (Baker 1928), exilis (Anthony 1860), and gibba (Currier 1867) were not actually forgotten.  If you look forward into Burch’s “Species List, Ranges, and Illustrations” on page 92, you will find them synonymized under Campeloma decisum.

[34] “Huntsville or Stevenson, Alabama.”  This was corrected to Decatur, AL by: Clench, W. J. and R.D. Turner (1955) The North American genus Lioplax in the Family Viviparidae.  Occasional Papers on Mollusks, Museum of Comparative Zoology, Harvard. 2(19): 1 -  20. 

Tuesday, March 9, 2021

A Gene Tree for the Worldwide Viviparidae

I may be mellowing in my old age.  I’m not sure.  Isaac Lea and his 505 species of pleurocerids used to tick me off something fierce, as opposed to merely driving me nuts [1].  I used to be irritated by F. C. Baker’s 30 species and subspecies of fossarine lymnaeids, now I’m merely frustrated [2].  I’ve come to understand that we scientists, no different from everybody else, can only operate by the standards of our day.  Isaac Lea’s science was good by the standards of 1862, and Baker’s great by the standards of 1911.  I’m trying to give everybody the same breaks I hope I myself will be given 100 years from now.

So I used to find gene trees very nearly intolerable.  They started popping up in the peer-reviewed literature of the 1990s, and forests of them were disgorged from the printers of earnest graduate students in the 2000s and straight into some of the best journals publishing at that time, each pocked and wilted by some or all of the same seven cankers:

(1) The typical gene tree is typological.  During the first 10 – 15 years of the fad, the community of molecular phylogenetics rarely demonstrated any appreciation of intrapopulation or interpopulation genetic variance whatsoever.  The authors of gene tress all seemed to follow what I have described as the U1S2NMT3 rule [3], with usually one, sometimes two, never more than three individuals per population, and usually one, sometimes two, never more than three populations per species, and so forth.  At these tiny sample sizes, the significance of any sequence variation that may be brought to light cannot be assessed. 

Figure S7 of Stelbrink et al. [7]

(2) By the mid-2000s, however, sample sizes were occasionally N > 3.  At that point it became clear that intrapopulation sequence variation could surpass interspecific variation, at least in the mtDNA of freshwater and terrestrial gastropods [4].  The authors of U1S2NMT3 gene trees could not accommodate this important finding and so ignored it.

(3) Typical gene trees are rarely standardized.  Their authors often demonstrate no appreciation for original descriptions or type localities, identifying the U1S2NMT3 snails they select for sequencing by unspecified criteria.

(4) Computational phylogenetics is a nightmare fifty-years running, from which evolutionary science cannot seem to wake.  Dozens of methods have been proposed to germinate and fertilize gene trees, each with a unique set of assumptions, through which the phylogenetics community, riven by fad and fashion, cycles endlessly.  Even unto this day, the authors of gene trees typically run multiple data analyses, and publish multiple trees, from which they select their favorite.

(5) Gene trees are not species trees, or population trees, for that matter [5].  The phenomenon of incomplete lineage sorting guarantees that some fraction of the gene trees produced for any set of populations will yield a misleading picture of their evolutionary relationship, and indeed coalescence theory can be used to predict what fraction of gene trees will be flat wrong, and the molecular phylogenetics community has no way to deal with this problem, so they have doubled-down on it.

(6) Finding themselves unable to accommodate reproductive isolation in their evolutionary models, the phylogenetic community has redefined the word “species” away from a rigorously-scientific biological concept to something (anything!) their technique can actually measure.  By 2007, the USNM cladist Kevin De Queiroz was listing five species concepts, either appropriated by molecular phylogeneticists or ginned up afresh, all of which depended on arbitrary judgement calls about the significance of branch lengths and clumps [6].

(7) And then they argued that the usually-one, sometimes-two, and never-more-than-three random snails they plucked out of random creeks and identified arbitrarily constituted endangered species by criteria only they themselves could judge and wrote grant proposals to natural resource agencies to find more such precious jewel boxes of biodiversity and got them funded.  And repeat.

By the mid-2000s, the technology had reached the point that grad students were sequencing 40 -50 individual snails per dissertation, from which they were generating 40 – 50 gene trees under 40-50 different analytical assumptions, picking the result most likely lead to additional funding.  I would sit in darkened seminar rooms for hours, watching gigantic gene trees labelled with tiny fonts, branches lit up in T-Mobile fuchsia and Mountain Dew green, and I would get such a headache.  Molecular phylogenetics is the rap music of evolutionary science, I thought – a tragic fad, a quick and easy path to job security in academia, surely it will go away.  But it hasn’t.  Neither has.

But in the last 5-10 years I have come to understand that the community of molecular phylogenetics looks at our science from a different perspective.  I look up and cannot imagine how one would begin to construct an evolutionary model of higher taxa until one had a strong model of the evolution of populations and species.  They look down and think of species and populations as following from higher taxa.  I want to make the gene tree the last chapter of my dissertation, they want to make it the first of theirs.  I think of gene trees as dependent variables, they think of them as independent variables.

From Fig. 2 of Stelbrink et al. [7]

And sample sizes have improved, as sequencing technology has advanced.  I do think I see more standardization by type locality, more calibration by intra- and interpopulation variance, methodologies to identify “bar-coding gaps,” and so forth.  At least some fraction of the molecular phylogenetics community now seem to offer their gene trees as weak, null models of population relationship, not as dowsing rods to wellsprings of imperiled biodiversity or guideposts to the promised land of rank-free classification systems.  And as that they are useful.   I guess I’ve become more forgiving.

So early last year a U1S2NMT3 gene tree of the old school crossed my desk, and it did not tick me off nearly as much as it would have ten years ago [7].  The sequence data analyzed came from a sample of viviparids worldwide in scope, which is always commendable, collected by 16 authors from 11 different countries.  And I guess I can forgive its young first author, Björn Stelbrink (who lists both German and Swiss addresses) for ignoring intraspecific variance, given 61 nominal species in 24 nominal genera over five continents.  Doggone tree is big enough.  T-Mobile fuchsia would have been next [8].

Stelbrink and his colleagues sequenced three genes, mitochondrial CO1 and nuclear 28S and H3, for 193 individual snails.  And depicted above is the bottom half of their “BEAST-MCC” tree [9] from concatenated sequences, with “Bellamyinae – clade B” trimmed off.  The branches I have deleted – 40 tips assigned to 13 genera, are entirely Asian and African, and do not concern us in North America.

And here is the first thing to notice.  The two big oriental species widely introduced in the USA, labelled Cipangopaludina chinensis and Cipangopaludina japonica above, did not cluster in the mixed Asian/African "Bellamyinae - clade B" with Bellamya (s.s.).  They clustered in the (entirely Asian) “Bellamyinae – clade A.”

Cipangopaludina was proposed by Harold Hannibal in 1912 as a subgenus of Pilsbry’s (1901) Idiopoma for Reeve’s (1863) Paludina malleata of Japan [10].  Hannibal was working from California populations of what we would today call C. japonica [11].  Clench and Fuller (1965) considered Idiopoma a simple synonym of Viviparus, continuing to accord Cipangopaludina subspecific rank [12].  Gary Pace [13] was the first to elevate Cipangopaludina to the full genus level, working with the native fauna of Taiwan.  When Burch [14] followed Pace, the rank of Hannibal’s Cipangopaludina was firmly fixed at the genus level.  And our two introduced species entered the canon as Cipangopaludina japonica and Cipangopaludina chinensis.

Those two species were universally assigned to the genus Cipangopaludina from around 1980 until 2000, when Doug Smith [15] pointed out that the characters by which Hannibal had described his genus were weak and variable, and that the rest of the world, including most workers in the countries from whence our two large viviparids must have been exported, were referring them to the genus Bellamya.

The Frenchman Félix Pierre Jousseaume proposed the genus Bellamya in 1886 to hold his typical B. bellamya, a large viviparid sent to him from Senegal [16].  Stelbrink and colleagues did not sample Jousseaume’s typical species (darn it), but they did include on their tree 15 other Bellamya samples from around Africa, and all of them clustered tightly in Clade B.

Cipangopaludina, again [17]

So the gene tree reproduced above now convinces me that our introduced species are best allocated back to Cipangopaludina, as they were classified from 1980 – 2000, rather than to Bellamya (ss), a genus name that probably ought to be reserved for African taxa.  It bothers me, a little bit [18], that Hannibal never visited Japan, proposing Cipangopaludina from America with no reference to any other viviparid taxa that might inhabit the waters of their native East Asia.  But subjectively, looking at the Stelbrink gene tree, I do see the appeal of separating Bellamyinae Clade A and Clade B as different genera.  And of the eight genus names applied to Clade A (Torotaia, Angulyagra, Sinotaia, Anularya, Celetaia, Margarya, Heterogen and Cipangopaludina), Hannibal’s Cipangopaludina is second-oldest [19].  And certainly, the first-most familiar here in America.

One other little feature of Stelbrink’s gene tree we might notice, before closing this month’s essay.  Viviparus georgianus was described by Isaac Lea from Hopeton, Georgia in 1834, and up until the 20th century was unknown in waters further north.  Clench [20] dated its arrival in the northeastern United States to Boston in 1916, from whence it has spread widely, across New England and New York through Michigan, Illinois and Wisconsin, even into southern Canada. 

Arthur Clarke [21] noted the striking similarity between Canadian populations of V. georgianus and the European Viviparus viviparus, speculating that Canadian Viviparus populations might represent a cryptic invasion from Europe.  The sequence data do not bear this hypothesis out, however.  The gene tree above depicts three European species, V. viviparus, V. ater, and V. contectus, as strikingly divergent from the North American V. georgianus, V. subpurpureus, and Tulotoma magnifica.  The Stelbrink results do not directly address Clarke’s cryptic invasion hypothesis, as the individual V. georgianus Stelbrink sequenced seems to have been collected from Alabama [22].  But GenBank also holds several CO1 sequences from V. georgianus populations sampled in Canada and New York, and all those demonstrate 98-99% matches to Stelbrink’s Alabama sequence, roughly 85% similar to the nearest European Viviparus.

So gene trees, even old-school U1S2NMT3 specimens such as we have reviewed in the present blog post, can offer some insight into coarse genetic relationships among far-flung taxa.  But how about more interesting and important questions?  Stelbrink and his colleagues also seem to have included six nominal species of Campeloma in their analysis, one snail each, in that orange block near the bottom of their tree.  Can their cute little data set tell us anything about population relationships among the North American Campeloma?  Tune in next time.


[1] This is a reference back to my series of essays on Pleurocera troostiana:

  • Isaac Lea Drives Me Nuts [5Nov19]

[2] We’re going to have much more to say about the crappy little amphibious lymnaeids often referred to as “fossarines” in coming months.  But for now, see:

  • The Legacy of Frank Collins Baker [20Nov06]
  • The Classification of The Lymnaeidae [28Dec06]
  • The Lymnaeidae 2012: Fossarine Football [7Aug12]

[3] For coinage of the “U1S2NMT3 Rule,” see:

  • The Lymnaeidae 2012: Stagnalis yardstick [4June12]

[4] For all you could ever want to know about intrapopulation mtDNA sequence divergence, see:

  • Mitochondrial Superheterogeneity: what we know [15Mar16]
  • Mitochondrial Superheterogeneity: What it means [6Apr16]
  • Mitochondrial Superheterogeneity and Speciation [3May16]
  • Mitochondrial heterogeneity in Marstonia lustrica [3Aug20]

[5] For more about gene trees and reproductive isolation, see:

[6] Five of the 11 species concepts listed in de Queiroz Table 1: Evolutionary, Phylogenetic (Hennigian), Phylogenetic (Monophyletic), Phylogenetic (Genealogical), and Phylogenetic (Diagnosable).  See: De Queiroz, K. (2007)  Species concepts and species delimitation.  Syst. Biol. 56: 879 – 886.

[7] Stelbrink, B., R. Richter, F. Köhler, F. Riedel, E. Strong, B. Van Bocxlaer, C. Albrecht, T. Hauffe, T. Page, D. Aldridge, A. Bogan, L-N. Du, M. Manuel-Santos, R. Marwoto, A Shirokaya, and T. Von Rintelen (2020)  Global diversification dynamics since the Jurassic: Low dispersal and habitat-dependent evolution explain hotspots of diversity and shell disparity in river snails (Viviparidae).  Systematic Biology 69: 944 – 961.

[8] In fact, both Stelbrink’s Figure 3 (unconstrained versus fossil-constrained tree) and his Figure 4 (Ancestral state estimation tree) did go T-Mobile-Fuchsia on us, plus Mountain-Dew-Green and a Change-of-Life-Blue that reminded me of a pants suit my wife bought at a yard sale in 1997.  Ouch.

[9] The most recent cycle of fad and fashion in computational phylogenetics seems to have brought to the top a cross-platform program called “BEAST,” Bayesian Evolutionary Analysis Sampling Trees.  The Stelbrink tree was generated using the “MCC” algorithm, Maximum Clade Credibility.  Oh good, that’s what's wanted around here.  Maximum credulity.

[10] Hannibal, H. (1912)  A synopsis of the Recent and Tertiary land and fresh water Mollusca of the Californian Province, based on an ontogenetic classification.  Proceedings of the Malacological Society of London 10: 112 – 211.

[11] Large, exotic viviparids, initially identified as Paludina japonica, were first recorded in San Francisco fish markets around 1892.  The first record of a naturalized population seems to be Stern’s 1901 report from the San José area.  For more, see:  Hannibal H. (1911) Further notes on Asiatic Viviparas in California.  Nautilus 25: 31 – 32.

[12] Clench, W.J. & S.L.H. Fuller (1965) The genus Viviparus (Viviparidae) in North America. Occ. Pap. Moll., 2(32): 385-412.

[13] Pace, G. L. (1973) Freshwater Snails of Taiwan (Formosa).  Malacological Review Supplement 1: 1 – 118.

[14] 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).

[15] Smith, D.G. (2000) Notes on the taxonomy of introduced Bellamya (Gastropoda: Viviparidae) species in northeastern North America. Nautilus 114: 31-37.

[16] Jousseaume, F. (1886) Coquilles du Haut-Senegal.  Bulletin de la Societe Zoologique de France 11: 471 – 502.

[17] The photo above of the impressive Cipangopaludina japonica die-off was snapped 12Jan21 by Mr. Brandon Jones, the Catawba Riverkeeper, on the muddy shore of the Fishing Creek Dam tailrace, at Great Falls, SC.  This point is about 30 km upstream from the Wateree Dam, which I described as:

[18] It shouldn’t.  Remote description of distant biotas has been standard operating procedure in systematic biology for 200 years.  The Europeans got all our pretty seashells, darn them.

[19] Actually, Margarya was described by Neville in 1877.  If I were a Pharisee, I would demand that our two big viviparid guests here in North America be identified as Margarya japonica and Margarya chinensis.  But let’s see how opinion evolves in The Orient.  I suppose it is possible that some actual biology might come into play here, as well.

[20] Clench, W.J. (1962) A catalogue of the Viviparidae of North America with notes on the distribution of Viviparus georgianus Lea. Occ. Pap. Moll., 2(27): 261-287.

[21] Clarke, A.  (1981)  The Freshwater Molluscs of Canada.  National Museums of Canada.  445 pp

[22] I am not entirely sure on Stelbrink’s V. georgianus locality.  There seems to be an error on that line in his Supplementary Table S1.

Tuesday, February 9, 2021

The Emperor, the Non-child, and the Not-short Duct

In last month’s post [5Jan21] I conducted you, my loyal and long-suffering readership, through the long and agonizing process by which I was personally able to distinguish the Floridian Helisoma duryi from the broadly-North-American Helisoma trivolvis.  The characters that ultimately did the trick for me, after years of abject confusion, were entirely shell morphological.

Nobody has subsequently asked me any of the natural follow-up questions, but I’ll bet a lot of you thought them.  Might there also be some sort of anatomical difference between H. duryi and H. trivolvis?  Did I ever dissect any of those snails?

The quick answers are “maybe” and “Fuhgeddaboudit.”  The rationale behind those answers, however, is far from quick.  So if you’re thirsty for another deep dive into the obscure history of another obscure malacological topic, full of obscure characters summoned from their graves to further muddy the already murky waters, read on.  Otherwise, I’ll see you next month.

Frank Collins Baker is a hero of mine.  That was the opening sentence of my blog post way back in [20Nov06], subsequently becoming the opening sentence in Volume 2, Essays on the Pulmonates published by the FWGNA Project in 2019 [1].  I’ve said it three times now.  I’m serious, I mean it.

Baker's 1902 Helisoma trivolvis [2]

Baker’s work was not modern.  He died in 1942, the year Ernst Mayr proposed the biological species concept.  But I would hold Baker’s work up as the zenith, the pinnacle, the very paragon of late pre-modern systematic malacology.  And as exhibit A, I would direct the jury to Baker’s treatment of one of the most common, widespread, familiar gastropods of North America fresh waters, Helisoma trivolvis.

Baker published his first study of Helisoma trivolvis in the second volume of his groundbreaking “Mollusca of the Chicago Area” [2].  As of 1902, he was still considering Planorbinae a subfamily of the Family Lymnaeidae.  So, after devoting a page of description to the genus Planorbis of Guettard 1756, and a brief treatment of the subgenus Helisoma of Swainson 1840, Baker devoted three pages to Planorbis (Helisoma) trivolvis (Say 1817), including 11 references, an original drawing of the radula and a 12 x 4 table of shell measurements.  And in his plate xxxii, he treated us to 15 photographic shell images, including a growth series.

Baker returned to the subject of Helisoma trivolvis in Part 1 of his landmark “Freshwater Mollusca of Wisconsin” [3].  By 1928 he was considering the Planorbidae a separate family, to which he devoted five pages of description, using H. trivolvis as exemplar for the family, drawing the external morphology of the animal and its stomach.  Then to the genus Helisoma he devoted nearly six additional pages of description, with drawings of a living adult crawling, a living juvenile crawling, the jaw morphology, and a lovely, detailed figure of the H. trivolvis reproductive system, including genitalia.

As of 1928, Baker had transferred H. trivolvis to the subgenus Pierosoma of Dall (1905), to which he devoted another page of description, with the figure of the penial morphology reproduced below.  The blue circle is the penial gland (internal in this view), the red circle is the bump on the exterior [4] of the penis corresponding to where that penial gland is sitting, and the arrow shows the duct leading from the penial gland to the sac around the penis.  Then (finally!) we arrive at the description of Helisoma (Pierosoma) trivolvis, the typical subspecies, which warrants another four pages of text, 14 references, a 9 x 4 table of shell measurements, a radula figure, and 15 shell figures on Baker’s Plate xx.

I will simply mention, in passing, that Baker recognized two subspecies of Helisoma trivolvis other than the typical, including H. trivolvis pilsbryi (Baker 1926), to which he devoted an additional four pages.  And an additional eight pages to three other species in the subgenus Pierosoma, including truncata (Miles 1861), all of which we now understand to be junior synonyms of H. trivolvis.  There is no evolutionarily-significant difference between the two penial complexes Baker drafted below – just accidents of preservation.  By now, you must get the picture.

And I will also remind my readership at this point that Baker was not done with the Planorbidae.  Both his 1902 work and his 1928 work were printed in octavo.  His worldwide “Molluscan Family Planorbidae,” published posthumously in 1945, was a quarto volume of 530 pages [5].

From Baker [3] Circles = penial gland, Arrow = Not short duct

Alas, my hero passed away on May 7, 1942, leaving his planorbid monograph unfinished.  He did, however, write a draft of his preface in January of that year.  And here is the topic sentence of preface paragraph two:

“Unlike the terrestrial pulmonates (Stylommatophora Pulmonata) which have been brought to a high state of precise classification from the anatomical studies of Dr. Henry A. Pilsbry and his co-workers, the Basommatophora are still in a condition of more or less chaos as regards classification, all of the monographs and many of the local studies being based wholly or partly on characteristics of the shell…”

. . . and so forth.  The hero of my hero was Dr. Henry A. Pilsbry.  Pilsbry was Baker’s mentor 1889 - 1890 and wielded immense influence over North American malacology for 70 years.  So, in December [3Dec20] we opened the cover of Pilsbry’s 1934 contribution to the biology of the Planorbidae, focused on Florida but aspiring to worldwide scope [6].  We are now in a position to evaluate Pilsbry’s paper in its historical context – after Baker 1902, after Baker 1928, and before Baker 1945.  How did His Imperial Majesty’s 1934 contribution compare to that of the colleague who idolized him?

Pilsbry’s introductory material is almost entirely acknowledgement, in which he lists a variety of curators, colleagues and correspondents from all over the USA, neglecting Baker.  Then he heads his second page with “Helisoma, Subgenus Pierosoma Dall,” subheads “Helisoma trivolvis intertextum (Sowb),” and lists four references.  These are to Planorbis glabratus Say of Binney (1865), which Pilsbry hastens to stipulate are “not the description; not of Say,” Planorbis intertextus of Sowerby (1878), Planorbis tumidus Pfr of Simpson (1887) which Pilsbry hastens to stipulate is “Not of Pfeiffer,” and “?Planorbis glabratus var. reticulatus Dall” of Bartsch (1916), which Pilsbry notes was “name only.”

Pilsbry then just launches in, assuming that we, his readership, are already familiar with planorbid anatomy.  More even than broad-brush planorbid anatomy, Pilsbry assumes that we are familiar with the detailed anatomy and shell morphology of typical Helisoma trivolvis trivolvis.  So this is how his description begins:

“The southeastern form of the Austroriparian H. (Pierosoma) trivolvis lentum (Say) is distinguished by its smaller size and flatter form.  The inner whorls of the shallowly concave left side are flattened and have an acute keel, normally concealed in the suture, the last whorl normally becoming rounded on that side.  The right side…”

… and so forth.  Pilsbry seems to have measured but a single shell of H. trivolvis lentum, for which he reports, “Diam. 17, alt. 5.5 mm; 5 ½ whorls.”  What, precisely, is this shell smaller and flatter than?  Smaller and flatter than the 12 x 4 table of shell measurements that his disciple F. C. Baker published from the Chicago area H. trivolvis in 1902?  Smaller and flatter than the 9 x 4 table of shell measurements Baker published from Wisconsin H. trivolvis in 1928?  Why didn’t Pilsbry cite any of the work of F. C. Baker?

Not only is Baker’s name entirely absent from Pilsbry’s review of H. trivolvis [7], none of the 14 H. trivolvis references that Baker listed in 1928 were passed along by Pilsbry, including Say’s original description of 1817.  All we were given for comparison is the intertextus of Sowerby, the not-description of glabratus published by Binney, the tumidus not of Pfeiffer, and the name-only reference to glabratus in Bartsch.  Pilsbry admits no antecedents.  Angels have led him to a stone box buried in upstate New York and stood over his shoulder as he has transcribed his description of Helisoma trivolvis lentum from golden plates he has discovered therein.

This is more than an unprofessional slight.  Pilsbry’s cavalier disregard of prior research has scientific consequences for us who labor in his footsteps today.  The main point of the first section of Pilsbry’s 1934 work was not to review Helisoma (Pierosoma) trivolvis, but to describe a new subgenus, Seminolina, into which he would segregate four Floridian species, including H. duryi.  What if some future worker, hypothetically of course, wanted to distinguish H. duryi, or indeed any of those Floridian Helisoma, from H. trivolvis?

Pilsbry described the shell only of H. trivolvis lentum; he apparently had no fresh or preserved material before him.  Nevertheless, on page 2 of his paper he jumped abruptly into the description of his new subgenus.  And here is Pilsbry’s definition of Seminolina, quoted in its entirety:

Helisomas in which the external duct from penial gland to upper sac is short and adnate. Shell shaped like Pierosoma or with the spire produced on the left side and scalar, Physa-shaped. The smooth or malleate surface is not thread-striate, usually glossy. Type Helisoma scalare (Jay).”

The ”shell-shaped-like-Pierosoma” character does not help us at all, and we beat that “not-thread-striate” shell character to death last month [5Jan21].  That leaves us with Pilsbry’s “duct-short-and-adnate” character.  Again, I ask.  Compared to what?

From Pilsbry [8]. Circles = penial gland, Arrows = "short" duct.

Before we go any further, I must emphasize that I am not criticizing Pilsbry for his subjectivity.  Subjective description was the standard of practice in pre-modern systematic biology, and the entire worldwide malacological community wrote stuff like “animal very dark olivaceous” or “duct short” or “penis ample,” including both F. C. Baker and H. A. Pilsbry, and I am not complaining about that.  Far be it from me to judge our esteemed forefathers by modern standards, like some common Democrat.

But I do not think it unreasonable, by 1934 standards, to expect Pilsbry to try to communicate to his posterity, ideally to show us, the difference between a duct that is short and adnate and a duct that is not short and not adnate, especially when he is erecting a higher-level taxon on the basis of that character.

So Pilsbry did offer us one lovely montage illustrating various aspects of the anatomy of his subgenus Seminolina, featuring H. scalare and three subspecies of H. duryi, as reproduced above.  He only labelled the penial gland on one of the ten figures he drafted of the Seminolina penis, but in fact that organ is illustrated six different times, in four different animals, as encircled directly on the figure above.  In almost all these figures, the penis is opened to expose the penial gland, circled in blue.  In four cases, circled in red, the penis has not been opened, so that the penial gland appears as a bump.

He never labelled the “external duct from penial gland to upper sac,” the key character by which the subgenus Seminolina is to be distinguished from the subgenus Pierosoma, in any of his figures.  It is best visible in figures B and J, where I have placed the red arrows, and sort-of visible, obscured by the penis, in figures C and K.  That is the organ which Pilsbry described as “short and adnate.”

So for a third time I ask, compared to what?  Insofar as I am aware, only one figure of the penial gland of Helisoma trivolvis had been published as of 1934, but it was a good one.  The penial gland is encircled in red in that figure from Baker 1928 I have reproduced way up above.  And the “external duct from penial gland to upper sac” of H. trivolvis which, to be precise, is not short and not adnate, is marked with a red arrow.

Baker’s 1928 figure was drafted at a larger scale than Pilsbry’s, it was offered in cross section, and it was semi-diagrammatic.  It cannot be compared to the figures Pilsbry has offered us in 1934 to support the distinction he has drawn between Pierosoma and Seminolina.  In two words, Pilsbry was artistic, Baker was scientific.  How are we, who follow in these great men’s footsteps, to distinguish the short from the not-short?

By the blessings of Divine Providence, however, F. C. Baker was, even at the time Pilsbry published his 1934 paper, working on his 1945 monograph [9].  Here he would compare duryi and trivolvis side-by-side, in some standard fashion.

In the figure below I have patched the top half of Baker’s Plate 24, showing the penial morphology of Helisoma trivolvis, together with the top half of his Plate 33, showing Helisoma duryi.  And again, I have marked the external duct from penial gland to upper sac, which Baker abbreviates “DC” for duct of gland, with red arrows.

From Baker [5]. Circles = penial gland, Arrows = penial gland duct.

OK, first set aside plate 24 figure 3, which depicts a juvenile H. trivolvis.  Then other than that case, I think I do see the phenomenon that Pilsbry was talking about.  The duct from the penial gland does indeed appear longer in Baker’s three adult H. trivolvis figures than in Baker’s eight H. duryi figures.

I have a couple misgivings, however.  First, some of the variance in the duct length is due to swelling in the penial gland to which it attaches, which (for example) is very pronounced in trivolvis figure 1 and duryi figure 9, but negligible in trivolvis figure 5 and duryi figure 1.  The same phenomenon is vivid in Baker's 1928 comparison of the Helisoma trivolvis and Helisoma truncata penial complexes way up above, which we now understand to be identical.

Of much greater concern, however, is that the entire penis appears taller and skinnier in all three trivolvis than in all eight duryi, not just the duct of the gland, but everything.  And in my experience, that usually means a difference in preservation.  It seems likely to me that Baker may have dissected his trivolvis alive, but his duryi preserved [10].

Here in the modern era of systematic biology, we understand that the length of a tube or duct of unreinforced epithelium in some exemplar or set of exemplars, carefully chosen or randomly selected, is not a good character by which to construct evolutionary hypotheses about animal populations.  It is too susceptible to non-heritable variance, too difficult to measure, and too subjective to describe otherwise.

In my mind’s eye, I see my hero, F. C. Baker, rising from the lab bench where he has just completed drafting his Plate 33, turning to the glittering malacological host assembled, and exclaiming,

 “There is no evidence that variance in the length of the penial gland duct is evolutionarily significant in Helisoma, but even if such evidence were to present itself, you can’t base a subgenus-level distinction on that single ridiculous character, for Chrissake!”

But Baker was not a naïve child standing in the crowd as The Emperor passed.  He was a courtier, following in retinue behind.  So, in the end, Baker’s observations confirmed those of his Emperor.  Here is the lead sentences in his remarks under the subgenus Pierosoma (pg 149):

Pierosoma is a very distinct group of Helisoma, distinguished from the subgenera Helisoma and Seminolina by peculiarities of genitalia and radula.  The duct of the penial gland is always longer in adult animals than in the other groups mentioned.”

I will conclude this month’s post with yet another confession of error, my third in three months.   In the brief biography of F. C. Baker I posted on [20Nov06], I referred to my hero as “the freshwater Pilsbry.”  Over the last several months, however, I have found many opportunities to compare the work of these two giants of late-premodern American malacology side by side.  And my earlier assessment was an insult to Baker.  Henry Pilsbry couldn’t carry F. C. Baker’s malacological jock strap.

Note added in postscript.  As I wrote the essay above I tried to maintain a professional distance from the subject matter, aiming for a strictly objective and dispassionate review of previous research on certain obscure details of planorbid reproductive anatomy, failing.  In the essay that follows, posted [26Jan21], I have explored the personal relationship between Pilsbry and Baker, making no pretense of professionalism whatsoever.


[1] For a bit of biography and a quick review of his contributions, see either:

  • Dillon, R. T., Jr. (2019b)  The legacy of Frank Collins Baker.  pp 1-5 in The Freshwater Gastropods of North America Volume 2, Essays on the Pulmonates.  FWGNA Press, Charleston. [FWGNA Publications]
  • The Legacy of Frank Collins Baker [20Nov06]

[2] Baker, F.C. (1902)  The Mollusca of the Chicago Area, Part II, The Gastropoda.  The Natural History Society Bulletin 3: 131 – 410.  Chicago Academy of Sciences.

[3] Baker, F.C. (1928) Freshwater Mollusca of Wisconsin, Part I, Gastropoda. Bull. Wisc. Geol. Natur. Hist. Survey, no. 70. Madison: University of Wisconsin Press.

[4]  Actually, during copulation this entire organ is everted like you’d turn out a sock.  So whatever is internal in this image would be external during copulation, and vice versa.  All those ducts and tubes are, of course, inside the penis when it is doing its job.   But the convention (at least in the late premodern tradition) is to call things “internal” in their dissected view, such as we have here.

[5] Baker, F.C. (1945) The Molluscan Family Planorbidae. Urbana: University of Illinois Press.  530 pp.

[6] Pilsbry, H. A. (1934)  Review of the Planorbidae of Florida, with notes on other members of the family.  Proceedings of the Academy of Natural Sciences of Philadelphia 86: 29 – 66.

[7] Pilsbry only referred to Baker’s 1928 work four times, all in his second section, almost entirely to dismiss it.  In his discussion of the reproductive anatomy of Planorbula, for example, Pilsbry footnoted: “Baker's figures seem to be somewhat diagrammatic, and do not agree fully with those I prepared for the unpublished New York monograph, especially in the form of the prostate gland and various details of penial structure.”  What, exactly, doesn’t agree with observations you haven’t published?  And never will?  Jackass.

[8]  Here is the full caption of Pilsbry’s [6] Figure 1: Fig. la, teeth of Helisoma scalare; b, genitalia; c, d, the penis opened, in d the penial gland of same specimen pulled downward; e, jaw. f, g, Helisoma duryi intercalare, penis and penial gland. h-h1-h2, genitalia of Helisoma duryi normale, at h1, the penis opened. i, j. k, H. d. seminole, penes. pg, penial gland; pr, prostate gland; v, verge.

[9] In his preface of January 1942, Baker said, “The present volume on the Planorbidae was begun some twenty-five years ago and has been in active preparation for the past ten years.”  Pilsbry almost certainly knew that Baker was already hard at work on the Planorbidae in 1934.

[10]  Indeed, problems of this same sort were noted by Pilsbry.  Under H. scalaris (p 35), he wrote: “The stouter shape of the verge in H. d. seminole may be due to greater contraction, as the specimens had evidently been killed in strong alcohol.”

Tuesday, January 26, 2021

Dr. Henry A. Pilsbry was a Jackass

Editor's Note: The only reason I am posting the brief essay that follows is that I need to blow off some steam.  This is entirely personal.  I apologize in advance.

In the winter of 1888-89, while he was yet a student at Brown University [1], my hero Frank Collins Baker [2], just 21 at the time, undertook an expedition to the little fishing community of Micco, Florida, on the Indian River Lagoon.  There he “had the opportunity to compare the species which are common to both the Northern and Southern shores.”  He seems to have collected at least 19 lots of shells during his explorations around Micco, including land snails as well as marine gastropods and bivalves, to judge by collections subsequently catalogued into the ANSP.

From Clench & Turner [3]

The following summer Baker accepted a Jessup Scholarship to work with Dr. Henry A. Pilsbry and moved to Philadelphia, carrying the collections he had made around Micco with him.  And in September of 1889, his mentor Pilsbry published Baker’s first scientific paper [4] in the very first volume of The Nautilus [5], entitled “Notes on Floridian Shells” [6].  Here is the third paragraph of that four-paragraph note, quoted in its entirety:

“I was very much surprised to find in one of my hauls with the dredge, a number of very perfect specimens of Turbonilla interrupta Totten, associated with Odostomia interrupta Say, and also Nucula proxima Say.”

Those “Turbonilla” shells, subsequently reidentified as Truncatella pulchella (Pfeiffer) [7], can still be seen in the ANSP collection today, catalogue numbers 60124 for adults and 60344 for juveniles.  Their locality data remain exactly as Baker wrote on his labels in 1888, and as he published in 1889, “off Micco, Fla., Indian River.”

The image below was posted on Facebook back in April of 2019 by our good friend Paul Callomon, collection manager at the Academy of Natural Sciences of Philadelphia.  It shows an outrageous slander on the name of my hero, written in the unmistakable chicken-scratch of Dr. Henry A. Pilsbry.

This is inexcusable.  I cannot find any reason to doubt that F. C. Baker collected those two lots of shells from the Indian River at Micco.  But if Pilsbry did have doubts, he could have broached them with his young protégé right there man-to-man, as Baker was standing in front of his editorial desk, manuscript in one hand and shells in the other.  There can be only one reason that Pilsbry accepted Baker’s paper, published it, and then impugned the young man’s character because of it.  Dr. Henry A. Pilsbry was a jackass.

Thanks, I feel better.


[1]  H. J. Van Cleave (1945) “A memorial to Frank Collins Baker (1867 – 1942).  Pp xvii – xxxvi in, Baker, F.C., The Molluscan Family Planorbidae.

[2] For a brief biography of my hero, see:

  • The Legacy of Frank Collins Baker [20Nov06]

[3] Clench, W.J. & R. Turner (1948) The genus Truncatella in the Western Atlantic.  Johnsonia 2: 149 – 164.

[4] He had one prior publication – a description of the Conchology Department in “The Old Curiosity Shop” of California.

[5] Volumes I and II were entitled “The Conchologist’s Exchange.”  Pilsbry picked up the subscription list of The Conchologist’s Exchange, and hence began publication of The Nautilus in May of 1889 with Volume III.

[6] Baker, F. C. (1889) Notes on Floridian shells.  Nautilus 3: 53 – 54.

[7] The sample that Baker identified as the pyramidellid “Turbonilla interrupta” turns out to be Truncatella pulchella, an amphibious gastropod of Florida and Caribbean coastal environments [8], apparently washed from its near-shore habitat into the deeper waters of the Indian River.

[8]  It is certainly possible that Pilsbry subsequently realized that Baker’s little sample of snails were truncatellids, not pyramidellids.  Then why not assume that Baker was mistaken in his identification, as the curatorial staff at the ANSP does today?  Why imagine that Baker lied about his collection locality?  Arrogant jackass!  Takes one to know one.

Tuesday, January 5, 2021

Collected in Turn One

If you’re just joining us.  This is the fifth essay in a long-running series on planorbids of the genus Helisoma in Florida. You really should be familiar with last month’s essay [3Dec20] before going forward, and it would help if you backed all the way up to 9Sept20 and read forward through 5Oct20 and 9Nov20 as well.

Is it possible for anyone alive today to visualize the lush and tangled jungle that must have greeted Mr. Charles Dury as he explored “places along the coast of Volusia County” in 1874?  Exiting I-95 at the US 1 interchange toward Ormond Beach in the late summer of 2020, I myself most certainly could not.

On the clipboard riding in the passenger seat beside me was a copy of Pilsbry’s (1934) review of Wetherby’s (1879) description of Helisoma duryi [1], “given to me by Mr. Charles Dury.”  And here is the Pilsbry quote I had circled in red:

“I am informed by Mr. Ralph Dury that in the trip of 1874 his father [Charles] visited places along the coast of Volusia County – Tomoka River, Port Orange, Daytona, Halifax River. […] It seems likely therefore that H. duryi was found somewhere along the eastern border of Volusia County [2].”

You, my readership, are now informed by Dr. Robert Dillon that the entire eastern border of Volusia County is, today, one enormous, congested sprawl.

My plan was to focus on the historic drainage of the Tomoka River, which like most of the Atlantic side of Florida, has been diked and filled by intensive development activities spanning many, many years.  The water was a bit brackish at my first stop, near the Ormand Beach airport (point X), so I drove a couple miles inland to the borrow-pit lakes at Ormond Beach’s Central Park (O).

Eastern Volusia Co, FL
And I must say that I was pleasantly surprised by the freshwater gastropod diversity [3] that greeted my eyes in the shallow, weedy margins of Ursa Minor Lake (29.2728, -81.0721).  The Helisoma population was sparse, however, and I only found a couple adults, and so I moved another 10 km south to a network of ditches draining toward the Tomoka River at Daytona (Point D).

Notice the checkered-flag motif on the wall above the ditch that I here offer as the H. duryi type locality [4], figured below.  Squatting down and dipping through the weeds, the adult Helisoma that met my eye would most certainly have been characterized by Henry Pilsbry as “large planorbes,” diameter ranging up to 2.54 cm that morning in August.  Standing up, I could see the Turn 1 grandstands of Daytona International Speedway.

I’m a NASCAR fan [5].  The relationship between snail collecting and stock car racing is exactly the same as the relationship between science and public policy.  Not compatible, but not incompatible either [6].

Essentially all the adult Helisoma I found alive in the eastern Volusia County region that Charles Dury apparently visited in 1874 seemed to bear slender or narrow shells with tight coils – significantly more slender than the figures of the type lot published by Pilsbry, see [3Dec20].  This was true both at Ormond Beach and at Daytona.  I think this may be the weedy, ditchy shell morphology.  But on the bank of the ditch at Daytona I found one relict shell that seems to match Pilsbry’s figures very nicely.  Might this be a memorial to what the eastern Volusia county environment looked like, 146 years ago?

So when I got home to Charleston, I dumped my fresh samples of bona fide Helisoma duryi out on the lab bench, got out the scope and looked at them real hard.  And I also pulled a nice batch of Helisoma trivolvis out of my collection from all over North America, including a topotypic sample I collected from an impoundment of French Creek way up in NW Pennsylvania in 2008 [7].  And the distinction, to be precise, is not shell form.

Ditch at Daytona [4]

In overall appearance, Helisoma duryi shells are short, tall, fat, skinny, and all over the place.  If the figure below does not convince you of that observation, look back at the figure I posted on [5Oct20], of shell morphology in H. duryi collected at the 40-mile bend, deep in The Everglades.  And compare those shells to the shell figure I posted on [9Nov20], depicting the shell morphology developed by that same population in culture.

For a while, I thought that I might be able to detect a difference in the tightness of the coil.  Some planispiral populations of H. duryi seem to demonstrate significantly more whorls to reach a given shell diameter than one ever observes in H. trivolvis (O and D below).  But again, look at the relic H. duryi shell, which matches Wetherby’s type.  The tightness of that shell coiling is not detectably different from H. trivolvis.

But every authority I have ever read has always mentioned, somewhere early in his description of H. duryi, something about shell shininess.  Wetherby [1] wrote, “Shell thick, shining, straw color, of medium size.”  For his new subgenus Seminolina, Pilsbry [2] wrote “The smooth or malleate surface is not thread-striate, usually glossy.”  Baker [8] agreed, saying “Surface smooth, usually glossy, without the threadlike striae of Pierosoma.”  The first character Thompson [9] offered us in his couplet #86 of dichotomous key was “shell dull” vs. “shell glossy.”  The former leads us to H. trivolvis, the latter to H. duryi.

I’ve read those words many times in the past, and the distinction between dull and shiny/glossy has never been clear to me.  Some of the bona fide H. duryi shells lying in piles on the lab bench before me were certainly shiny or glossy.  But some (like shell D below) most certainly were not.  And some H. trivolvis shells seem sort-of shiny, maybe.  Shininess is not measurable by any equipment conventionally available, and the cut point between duryi and trivolvis in international-shell-shininess-units has never been calibrated by any prior worker, in any case.  I needed something more.  Something objective.

O = Ormond, D = Daytona, Dr = relict

So what about those “thread-like striae?”  In the figure below I have collected all four of the images I published back in September, depicting juvenile Helisoma trivolvis.  And I have compared them to images of juvenile Helisoma duryi, collected at the 40-mile Bend, at Ormond, and at Daytona.  Also Lake Munson, way up in North Florida near Tallahassee – we’ll come back to that locality in a future essay.

If you click the image and examine an enlargement, the distinction is vivid.  The shells of juvenile H. trivolvis demonstrate what Pilsbry called “thread-like spiral striations” and the shells of juvenile H. duryi do not.  Projected out into adulthood, I am sure this yields the “shell dull” vs. “shell glossy” distinction that authorities have always noted.  But in juvenile shells the subjective element of the distinction is removed.

Also striking is that strong carination near the apex of the juvenile trivolvis shells (arrow), which Pilsbry called an “acute keel.”  That feature is not clear in the adult shells, at all, but adult trivolvis do tend to demonstrate “boxier” whorls than the more smoothly-planispiral duryi, with which may be a later manifestation of the juvenile keel.  The whorl-boxy character is not helpful unless you’ve seen a lot of both shells on the bench in front of you.  But once you’ve seen it, whorl-roundedness or boxiness seems to be a fairly reliable method of distinguishing the species as well as the threadlike spiral striations.

So I will conclude this month’s essay with another confession of error, my second in two months.  And this error is a whopper.

Juvenile H. trivolvis (above) and H. duryi (below)

Could I ask you all to look back at an essay I wrote in February of 2005 on shell morphology, current, and substrate in the Helisoma population of Wakendaw Lakes?  Open this link [18Feb05] in a new window.  I actually dredged that 2005 essay up again this past September, as an example of ecophenotypic shell variation in the planorbids generally.  You could look at my post of [9Sept20] too if you want.

For 15 years I have identified those snails from the Wakendaw subdivision east of the Cooper as Helisoma trivolvis.  But I fetched up a sample of juveniles this fall and scoped them out, and their shells are smooth as a baby’s bottom.  The Wakendaw Lakes population is Helisoma duryi.

I suppose I should not have been surprised, since that population came to my attention because it was biphasic, showing strikingly different shell morphologies on pond weeds above the little dam, and on riprap rocks in the current below.  Wakendaw Lakes look like a little patch of Florida, on the other side of Charleston, in retrospect.

But even here in my own neighborhood West of the Ashley, where all the Helisoma are uniformly planispiral.  The gigantic planorbid population in that office park about which I blogged on [29Nov04] is Helisoma duryi.  And most embarrassingly of all, the Charles Town Landing population that I sent to Cindy Norton as a “control” for the breeding experiments I detailed in [9Nov20] were also Helisoma duryi.  No wonder she found such strong evidence of reproductive compatibility between her Carolina population and the Helisoma population I collected at the 40-Mile Bend!  Ultimately, the most foolish thing about Cindy’s 2018 breeding experiments was her collaborator.

In recent months I have re-examined, and in many cases re-sampled, populations I have previously identified as Helisoma trivolvis from a broad swath of the southern Atlantic drainages.  I have discovered one population of H. duryi in coastal Georgia, which I collected on Sapelo Island in 2005, and one way up in the Atlanta area, certainly a recent introduction.  I have also confirmed 15 duryi populations in coastal South Carolina, from way down on Hilton Head Island, where I mentioned “H. trivolvis” in my blog post of [16Dec15], all the way north to the Myrtle Beach area.

I’ve been screwing up my local Helisoma for years.  In my own defense, I might quote Baker [8], who limited the range of H. duryi, and indeed the entire Pilsbry subgenus Seminolina, to “only in the peninsula of Florida north to Bradford County.”  Burch [10] quoted Pilsbry’s “Northern to southern Florida.”  No prior authority ever seems to have imagined that H. duryi might range as far north as the Carolinas.

Helisoma duryi becomes species #70 on the list of freshwater gastropods documented from the nine-state Atlantic drainage region of North America [11].  And here is the natural follow-up question, I suppose.  Is this species native or introduced to the region?  Pretty much all 17 of the H. duryi populations north of Florida of which I am aware [12] inhabit disturbed environments.  I can offer no better answer than the one that occurred to me on my ride home from Hilton Head Island five years ago.  Quoting my essay of [16Dec15]:

“I had spent three full field days sampling a freshwater benthic community comprised entirely of invasive species.  At some time scale, this insight is trivial.  Hilton Head didn’t even exist at the last interglacial period, so its entire freshwater and terrestrial biota must be invasive at a scale of 10^5 years.  But the gastropod community my SCDNR colleagues and I have been sampling this fall looks 10^2 invasive to me and might even be 10^1 invasive.”

Everything is invasive, and we humans are invasive, and it never hurts to remind ourselves occasionally that all biotas are dynamic.  As is science.


[1] Weatherby, A.G. (1879)  Notes on some new or little known North American Limnaeidae.   The Journal of the Cincinnati Society of Natural History 2: 93 – 100.  For more about Weatherby and his Helisoma, see:

  • The Flat-topped Helisoma of The Everglades [5Oct20]

[2] Pilsbry, H. A. (1934)  Review of the Planorbidae of Florida, with notes on other members of the family.  Proceedings of the Academy of Natural Sciences of Philadelphia 86: 29 – 66.  For more about Pilsbry and his 1934 contribution to our understanding of the Planorbidae, see:

[3] The freshwater gastropod fauna of Ursa Minor Lake: Helisoma scalaris duryi, Biomphalaria havanensis, Gyraulus parvus, Physa acuta, Physa pomilia, Melanoides tuberculata, Lymnaea columella, Pyrgophorus parvulus, Pomacea paludosa.

[4] The type locality for Helisoma duryi (Wetherby 1879), here designated: Ditch leading to the Tomoka River at the corner of Bayless & Fentress Blvds, 6 km W of Daytona Beach, Volusia County, FL. (29.1891, -81.0786)

[5] I’ve only attended the Daytona 500 once, in February of 2006, a race in which Jimmy Johnson took the checkered flag.  48 can kiss my ass.

[6] I’ve explored the relationship between science and public policy so often in the 20-year history of this blog that I’ve developed a separate label in the right-hand margin way up above, “Worldview Collision.”  The relationship is exactly analogous to science and sports, or music and sports, for that matter.  My daddy was both a baseball-player and a banjo-picker, but he never tried to make the two compatible.

[7] Thomas Say (1819) wrote that the “ingenious naturalist, Mr. C. A. Lesueur” found his sample of Planorbis trivolvis “in French Creek, near Lake Erie.”  My sample of H. trivolvis, which I offer here as topotypic, came from Howard Eaton Reservoir, an impoundment of upper French Creek in Erie County, PA.  (42.1476, -79.7658)

[8] Baker, F.C. (1945) The Molluscan Family Planorbidae. Urbana: University of Illinois Press. 530 pp.

[9] Thompson, F.G. (1999)  An identification manual for the freshwater snails of Florida.  Walkerana 10 (23): 1 – 96.

[10] 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).

[11] The 69-species list (FWGNA synthesis V2.1) was the one ultimately published as Table 2 in:

  • Dillon, R.T., Jr., M.J. Ashton, W.K. Reeves, T.P. Smith, T.W. Stewart, & B.T. Watson (2019a) Atlantic drainages, Georgia through Pennsylvania.  Freshwater Gastropods of North America, Volume 1.  FWGNA Press.  199 pp.   [FWGNA Publications]

Version 2.1 has subsequently been supplanted by FWGNA synthesis version 3.0 (with 102 species), currently on the website [synthesis].

[12] The only exception of which I am aware is a record of Helisoma duryi in the rather pristine Black River near Andrews, SC.  That population seems to be sympatric with H. trivolvis.  Significant in a couple respects, I think.