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

Editor’s Note – This essay was subsequently published as: Dillon, R.T., Jr. (2023c)  The Emperor, the Non-child, and the Not-short Duct.  Pp 271 – 282 in The Freshwater Gastropods of North America Volume 7, Collected in Turn One, and Other Essays.  FWGNA Project, Charleston, SC.

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.  Among the 507 pages of Baker's (1928) monograph one finds almost 25 devoted to Helisoma trivolvis, in a wide variety of forms.

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 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.

Notes

[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.”

Dr. Henry A. Pilsbry was a Jackass

Editor's Notes - 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.

This essay was subsequently published as: Dillon, R.T., Jr. (2023c)  Dr. Henry A. Pilsbry Was A Jackass.  Pp 283 – 286 in The Freshwater Gastropods of North America Volume 7, Collected in Turn One, and Other Essays.  FWGNA Project, Charleston, SC.

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.

Notes

[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.

Collected in Turn One

Editor's Notes - 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.

This essay was subsequently published as: Dillon, R.T., Jr. (2023c)  Collected in Turn One.  Pp 261 – 269 in The Freshwater Gastropods of North America Volume 7, Collected in Turn One, and Other Essays.  FWGNA Project, Charleston, SC.

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], depicted 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 flat or compressed 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 can be short, tall, fat, skinny, compressed, inflated, 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 H. duryi shell morphology deep in the Everglades at the 40-mile bend.  And compare those shells to the shell figure I posted on [9Nov20], depicting the 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 to the malacologist, 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 up 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.

Notes

[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:

• The Emperor Speaks [3Dec20]

[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.

The Emperor Speaks

Editor’s Note – This essay was subsequently published as: Dillon, R.T., Jr. (2023c)  The Emperor Speaks.  Pp 253 – 260 in The Freshwater Gastropods of North America Volume 7, Collected in Turn One, and Other Essays.  FWGNA Project, Charleston, SC.

I will begin my essay this month confessing an error that I committed in the late summer of 2018, as relayed to this group two months ago.  Here is a direct quote from my 5Oct20 essay on the “Flat-topped Helisoma of the Everglades”

“So, reading Wetherby’s description in the calm of my office here one sunny morning in Charleston a couple years ago, I was stricken with the impression that the type locality of Helisoma duryi might could use a bit of narrowing-down.  And I swiveled my chair and pulled my well-thumbed copy of F. C. Baker’s (1945) “The Molluscan Family Planorbidae” off the bookshelf.”

That was lazy of me.  I should have consulted Baker's mentor, the Elderly Emperor [1] Dr. Henry A. Pilsbry (1862 - 1957).

His regal ghost still flickered, dimly, through the hollow corridors of the mollusk collection at the Academy of Natural Sciences during my years as a graduate student in Philadelphia.  When I arrived at that venerable institution in the summer of 1977, the first stop on my first tour was the “Pilsbry Chaos,” a pile of boxes, papers, and shells through which curatorial assistants were still laboring, 20 years after the great man’s death. 

From H. B. Baker [2]

He was born on a small farm near Iowa City and seems to have developed his interest in land and freshwater shells at the nearby University, from whence he was awarded his B.Sc. in 1882.  Pilsbry then became a newspaper man, briefly, as was his contemporary Calvin Goodrich [3], moving to New York City as a proofreader in 1887.

He rocketed to malacological stardom almost immediately thereafter, at the age of 25.  On Thanksgiving Day of 1887, Pilsbry was invited to Philadelphia by George W. Tryon [4], who offered him a job as his assistant.  When Tryon died suddenly in February of 1888, Pilsbry inherited Tryon’s position as Conservator the Conchological Section, and Editor of the Manual of Conchology.  Pilsbry sat behind that high desk at the ANSP for 70 years, until they carried him out on a plank [5].

In 1889 he founded “The Nautilus,” the Volume 70 galleys of which were on the cluttered desk around which his plank was wedged.  Frank Collins Baker also came to Philadelphia to work with Pilsbry in 1889, and left the next year profoundly affected [6].  In 1890 Pilsbry organized the American Association of Conchologists, the first of several precursors to the American Malacological Union, of which he was elected first president.  In 1899 he was awarded a doctorate of science by his alma mater, the University of Iowa, the first of three doctorates he was ultimately to receive [7].

Pilsbry’s primary interest was in the North American land snails.  H.B. Baker characterized his (1895) “Guide to the Study of Helices” as “the most brilliantly original, iconoclastic book that ever has been written about the subject.”  Of land snails.  His four-volume “Land Mollusca of North America” (1939 – 1948) is the alpha of the American terrestrial gastropod fauna even unto the present day and may ultimately (I fear) prove to be the omega as well.

But the Elderly Emperor was widely published in freshwater, marine, and fossil malacology as well, from all over the world.  No one can count the sum of his works.  His biographers wrote, “an estimate between 3,000 and 4,000 possibly might cover the number of published articles that flowed from his facile pen.” Paging through the Burch canon [8], I count 57 species or subspecies of North American freshwater gastropods described by Pilsbry surviving even unto 1980, plus eight Pilsbry genera and three Pilsbry subgenera, in eight families.  Accepting Burch’s estimate of approximately 500 species, Pilsbry may be credited with describing over 10% of our freshwater gastropod fauna.  Not bad for a secondary interest.

So early in his career Pilsbry began taking regular vacations to Florida [10].  And in 1934 he published a large and wide-ranging paper in the Proceedings of the ANSP entitled “Review of the Planorbidae of Florida, with notes on other members of the family [11].”  The first 17 pages of that work were subtitled “I. The Large Planorbes of Florida,” which since not followed by a second section subtitled “The Small Planorbes of Florida,” turns out to have been what he meant by “The Planorbidae of Florida” in his main title, screw all those little ones [12].  The second 20 pages of Pilsbry’s 1934 paper were subtitled “Notes on Other Planorbidae,” which turned out to be an ambitious review of planorbid systematics across The Americas, with descriptions of a bunch of new species from three continents.  He described his new genus Australorbis about halfway through that second section, assigning Say’s (1818) glabratus to it, not helping [13].

Paratype lot of H. duryi in the UMMZ [9]

But it is the first half of Pilsbry’s 1934 paper that has brought him to our attention this month.  He began with Helisoma trivolvis, which (of course) is widespread throughout North America, which he allocated to the Dall subgenus Pierosoma.  He then undertook to describe a new subgenus, Seminolina, with Helisoma scalare (Jay 1839) as the type [14].  He also assigned to his new Seminolina two fossil species of Dall (conanti and disstoni) and “the Helisoma duryi complex.”  In the duryi complex he recognized, in addition to Wetherby’s typical subspecies of 1879, intercalare (Pilsbry 1887), preglabratum (Marshall 1926), and three new subspecies: seminole, normale, and eudiscus.  We touched briefly upon all this taxonomic churn back in October.  Sorry to bring it up again.

And regarding the type locality of Helisoma duryi, Pilsbry wrote: “Wetherby’s locality “Everglades of Florida” was vague and doubtless inexact.  I am informed by Mr. Ralph Dury [15] that in the trip of 1874 his father 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.”

D’oh!  Back in 2018, with F. C. Baker’s 1945 monograph open in my lap [16], I had convinced myself that a good typical (if not necessarily type) locality to sample H. duryi might be located on the Tamiami Trail at the 40-mile bend.  That is what sent me dodging airboats way down in The Everglades in October of 2018 [17], and that is why I had such high hopes for Cindy Norton’s 2019 breeding experiments [18].  In retrospect, I should have consulted The Elderly Emperor first.

In my own defense, here is the verbatim quote from Wetherby: “This shell was given me several years ago, by Mr. Charles Dury, who brought it from the Everglades of Florida.  It was also among the shells received from the Miami country.”  Volusia County is not in The Everglades, even under the most expansive modern definition of that term.  And Volusia is 250 miles north of Miami, and always has been.

Excuse logged.  Now go back to Florida, Dillon, and do your job right.

Digging into the Pilsbry paper further, it materializes that The Elderly Emperor examined Wetherby’s actual type lot, which Bryant Walker got hold of somehow, which sits in the UMMZ collection to this day.  That set of shells comprises a holotype (UMMZ 83501) and nine paratypes (UMMZ 83502) as figured above.  Pilsbry measured and figured four of the ten, including the holotype, which is where I got “19.5 mm” for footnote [3] of my October post.  And if you can believe it, Pilsbry split one of the shells out of Wetherby’s type lot of Helisoma duryi duryi into his own newly-described Helisoma duryi seminole.  See figure #4 in the Pilsbry montage below.

Wetherby’s type lot. #2 = holotype, #4 = H. d. seminole

Now would be an opportune time, I suppose, to make explicit what has, to this point in my essay, been implicit.  Henry Pilsbry was innocent of the Modern Synthesis.  The only species concept of which he was aware was the nineteenth-century “organism or group of organisms recognized as distinct by a competent taxonomist.”  Which Pilsbry, without question, was.  So, if His Imperial Majesty recognized a species, then it was a species, by definition.

And exactly the same for subspecies.  Under today’s modern synthesis of evolutionary thought, we define subspecies as “populations of the same species in different geographic locations, with one or more distinguishing traits [19].”  Pilsbry never considered that “different geographic locations” thing.  Subspecies were what he recognized as subspecies, just the same as species were what he recognized as species, only with less of whatever that species juice might be.

So although Pilsbry examined the type lot in Bryant Walker’s collection, it materializes that he never had any fresh Helisoma duryi duryi from anywhere in Volusia County in front of him.  Nor did his protégé Baker.  The type locality remained only slightly less mysterious to The Elderly Emperor than to me, reading his words in the calm of my office a couple months ago.

Volusia County is today home to approximately a half-million residents, 122 motels, 5 Walmart Supercenters, and the World Center of Racing.  Next month, we race off to Daytona!

Notes:

[1] R. Tucker Abbott (1958) coined that sobriquet on page 103 of his contribution to the Pilsbry festschrift: "From the Pilsbry Chair of Malacology."  Nautilus 71: 100 – 103.

[2] I have gleaned most of the biographical details relayed here from Baker, H.B. (1958) Henry Augustus Pilsbry 1862 – 1957.  Nautilus 71: 73 – 83.

[3] Calvin Goodrich (1874 - 1954) was an early-modern malacologist, Pilsbry the paragon of the late pre-modern.  For more, see:

• The Legacy of Calvin Goodrich [23Jan07]

[4]  We explored the relationship between George Tryon (1838 - 1888) and his immediate predecessor at the ANSP in:

• Isaac Lea Drives Me Nuts [5Nov19]

[5] Not really, but darn close.  He suffered a heart attack at his desk in September of 1957 and died in his sleep in October.

[6] For a bit of background on my malacological hero, see:

• The Legacy of Frank Collins Baker [20Nov06]

We will hear much more about the relationship between Baker and Pilsbry in coming months.

[7]  Pilsbry was ultimately awarded doctorates of science by the University of Iowa (1899), the University of Pennsylvania (1940), and Temple University (1941).

[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] We thank Taehwan Lee of the University of Michigan Museum of Zoology for braving the perils of the worldwide Coronavirus panic to assemble and photograph for us the lovely montage of H. duryi paratype lot 83502 reproduced above.

[10] Here’s a quote from T. L. McGinty (Nautilus 71: 97 – 100):  “Early in 1937, Dr. Pilsbry secured a cottage in Lantana, Florida, and each succeeding winter visit to his Florida home brought the Doctor new friends.”

[11] 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.

[12] Helisoma duryi, you may recall from my essay of October, was originally described by Wetherby (1879) as neither large nor small, but rather “medium-sized.”  Pilsbry (1934) folded the medium-sized planorbes in with the large.  I suppose we, the students who follow in the great man’s footsteps, should be grateful.

[13] Here’s a direct quote from H. B. Baker’s Pilsbry obituary [2]:

“Very rarely, when in a Puckish mood, did he (Pilsbry) wield his prestige to establish dubious cognomens; thus he argued against the use of Mesomphix instead of Haplotrema, but contrarily replace Planorbina guadaloupensis by (Biomphalaria) Australorbis glabrata (1934).”

I don’t know what that means, but it sounds important, so feel obligated to pass it along.

[14] John Clarkson Jay (1839) spelled the species name “scalaris” to agree in gender with the feminine Paludina.  Pilsbry re-spelled it scalare when he moved the specific nomen under the neuter noun-construct Helisoma in 1934.  Thanks to Harry Lee for the insight.

[15] We tipped our hat to Mr. Charles Dury in October footnote [4].  His son Ralph E. Dury (1899 – 1984) was Director of the Cincinnati Museum of Natural History for almost 60 years.

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

[17] If you haven’t read it already, you might be entertained by:

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

[18] And as long as you’re reviewing my previous posts, you might as well bring yourself up to date:

• Foolish Things With Helisoma duryi [9Nov20]

[19] To refresh your memory on the definition of the word “subspecies” as adopted by the FWGNA Project, see:

• What Is A Subspecies? [4Feb14]
• What Subspecies Are Not [5Mar14]

Foolish Things with Helisoma duryi

Editor’s Note – This essay was subsequently published as: Dillon, R.T., Jr. (2023c)  Foolish Things with Helisoma duryi.  Pp 245 – 251 in The Freshwater Gastropods of North America Volume 7, Collected in Turn One, and Other Essays.  FWGNA Project, Charleston, SC.

I first met Dr. Cynthia G. Norton in 2005, at the AMS meeting in Asilomar, California.  And I was immediately impressed by her warmth, by her outgoing personality, and by the rigor of her scientific inquiry, which in my long experience, is a rare combination.  She was interested in the same sorts of research questions in Helisoma that Amy Wethington and I were working upon at that time in Physa: mating behavior, sex allocation, and the reproductive biology of simultaneous hermaphrodites generally.  And we have corresponded regularly ever since, cataloguing the similarities in our research findings we have uncovered over the years, which are many, as you might expect.  The most important differences are that Helisoma mate reciprocally, face-to-face, while Physa mate unilaterally, male on top of female, after which swapping may occur.  And quite unusually for basommatophoran pulmonates, Helisoma rarely seem to self-fertilize [1].

In 2009 I lured Cindy into a collaboration with me involving the European Planorbarius corneus, an unpublishable disaster that yielded the sum total of one post on the FWGNA Blog [2].  But I love the quote that Cindy has always used to close her emails, even unto the present day: "You will do foolish things, but do them with enthusiasm - Colette [3]."

So in May of 2018 the mailman came knocking on my door with Volume 36(1) of the American Malacological Bulletin.  I was aware that Cindy had been working with an albino strain of Helisoma trivolvis for several years at that point.  So, I was not surprised to find her note confirming that albinism is inherited simple Mendelian recessive [4].  I think that has pretty much turned out to be true throughout the animal kingdom.  Amy and I had documented two non-complimenting albino loci in Physa back in 1992, which we used as a tool for all manner of interesting studies of reproductive biology [5].

Albino planorbids are much more spectacular than albino physids, however.  Planorbids have re-evolved hemoglobin as a respiratory molecule, and when albinism blocks their normal production of melanin, their bodies are rendered startlingly red [6].  Red-colored planorbids, universally marketed as “ramshorn” snails, may be the most commonly encountered aquarium snail in the world, that somebody actually wants to be in there [7].

The peculiar thing is this.  Nobody seems to know what those commercially-available “ramshorn” snails actually are, or where they might have come from [8].  The most common speculation is that they are Floridian Helisoma duryi, although H. trivolvis is sometimes mentioned in this regard, and Asian Indoplanorbis exustus, and even European Planorbarius corneus.  And indeed, even the relationship between the two American species, H. duryi and H. trivolvis, has simply never been clear.

So the seed of an idea began to germinate.  Might Cindy Norton be lured into another foolish collaboration with yours truly?  In June I wrote her to propose a set of breeding experiments with the two sister Helisoma species, and in light of her motto, I should not have been surprised that she replied affirmatively, with enthusiasm.  Cindy and I roughed out an experimental design involving three lines: her albino H. trivolvis, a stock of Helisoma duryi that I would supply from Florida, and a control (pigmented) stock of H. trivolvis from Charleston [9].  And now you know what, exactly, I was doing dodging airboats in The Everglades in late October of 2018 [10].

Cindy's culture technique

Like most animals with internal fertilization, pulmonate snails can store sperm for a long time – probably their entire lives [11].  Most of the Helisoma I sent to Cindy from Florida in October of 2018 were juveniles and might not be inseminated, I suppose.  But the pigmented wild stock Helisoma I sent her from South Carolina immediately thereafter were adults, and most of Cindy’s albino line were adults as well.  So before experiments could begin, Cindy would need virgins from all three lines.  She put our Florida snails (F) in one tank and our Carolina snails (C) in another and waited for eggs.

And indeed, both the Florida experimental-snails and the Carolina control-snails survived their harrowing late-autumn flights to St Paul, and indeed, both lines began to lay eggs.  And Cindy began to collect and isolate hatchlings from those two lines, and from her already-established albino (A) line as well.  Helisoma reach sexual maturity about 70 – 80 days post-hatch in Cindy’s lab [1], so our experiment entered a second waiting phase.

Alas, Cindy wrote me in January that the Florida hatchlings did not survive.  And in fact, most of the wild-born Florida snails also gave up the ghost in their first couple months under Cindy’s experimental conditions, as well.  The Carolina and Albino lines thrived, as did their lab-born hatchlings, so she felt as though the problem was not temperature, water quality, or any other aspect of her experimental technique.  The Florida snails just did not seem to culture well.  Some snails don’t.

But let’s back up a step.  You will recall that most of the snails I sent Cindy from Florida were juveniles.  On a whim, Cindy had paired 8 of those Florida-born snails with lab albinos, and 8 of the Carolina-born snails with lab albinos, and began collecting eggs from the albinos, looking for pigmented F1.  And here is what she found:

• From the Carolina x Albino crosses, 5/8 of the albino mothers produced at least some pigmented offspring.  A count of 34 egg masses laid by these five mothers yielded on average 54% pigmented.  The other 3 albino mothers produced only albino progeny.
• From the Florida x Albino crosses, 4/8 of the albino mothers produced at least some pigmented offspring.  A count of 24 egg masses laid by these four mothers yielded an average of 17% pigmented.  Three of the other mothers laid only albino offspring, and one mother was unproductive.

Yow.  When I read those results back in January of 2019, the first thing that jumped off my computer screen and landed in my lap was the similarity between the 5/8 outcross figure in the CxA control and the 4/8 figure in the FxA experiment.  Pigmented offspring from almost exactly half of eight matings, in both CxA and FxA, really?  And almost as amazing was Cindy’s discovery of mixed-phenotype egg masses from outcrossed mothers of both crosses.

Let me back up two steps and get a running start at this entire experiment.  As I mentioned at the top of this essay, Cindy’s previous research results seem to suggest that Helisoma rarely self-fertilize.  So exactly five of the eight albino snails she paired with Florida snails had previously mated with albino fathers, but nevertheless copulated with Florida snails, and bore some FxA hybrid F1.  And exactly four of the eight albino snails she paired with Carolina snails had previously mated with albino father, but nevertheless copulated with Charleston snails, and bore some CxA hybrid F1.  In mixed clutches [12].  The implied mating compatibility between a Helisoma trivolvis population from South Carolina and a Helisoma duryi population from the Everglades of Florida, bordering indeed on reproductive uniformity, is striking.

So were those hybrid F1 fertile?  Alas, we will never know.  In March Cindy regretted to inform me that all her hybrids expired – both the FxA and the CxA hybrids – which she attributed to problems with temperature regulation in the lab.

Helisoma egg mass, showing mixed phenotypes

Ultimately, the 2018 collaboration that I talked Cindy into with Helisoma duryi ended up being only slightly less foolish than the 2009 collaboration I talked her into with Planorbarius corneus.  One, single oral presentation was the sum total yield [13].  I was not in the audience when she presented our results at the University of Salford in April of 2019.  But I feel sure that she did so enthusiastically.

But wait, there’s more.  About 7 – 8 paragraphs ago I mentioned that “most” of the adult H. duryi I sent Cindy back in October 2018 died in January.  But some did survive, to maturity.  And in fact, Cindy was able to carry a pure culture of H. duryi in her St. Paul laboratory for a couple generations, alongside her pure controls from Carolina.  Photographs of which have been assembled into the montage that opened this essay.

Most of Cindy’s lab-born snails, including the first lab-born generation of H. duryi from Florida, developed typical, planispiral shells.  And a few developed shells with a low apex.  Now look back at last month’s essay.  Their parents, collected from submerged macrophytes in The Everglades, bore that peculiar, elongated (“scalariform” or “physoid”) shell morphology typically associated with H. scalaris.  Let’s explore that phenomenon further, shall we?

Notes

[1] Norton C.G. & B.R. Newman (2016)  Growth, reproduction and longevity in the hermaphroditic freshwater snail Helisoma trivolvis.  J. Moll. Stud. 82:178 – 186.

[2] I wrote about my travails bringing Planorbarius corneus into the USA for Cindy’s 2009 experiments in:

• Non-plants, non-pests, and non-sense at the USDA [17Dec08]

[3] I confess I had to google her.  Sidonie-Gabrielle Colette (1873 – 1954) was the French author best known for her 1944 novella Gigi.

[4] Norton, C.G., A.F. Johnson, and B.M. Nelson (2018)  The genetic basis of albinism in the hermaphroditic freshwater snail Planorbella trivolvis.  Amer. Malac. Bull. 36: 153 – 157.

[5] Dillon, R.T., Jr and A.R. Wethington (1992)  The inheritance of albinism in a freshwater snail, Physa heterostropha.  Journal of Heredity 83: 203 – 210. [pdf]  For more see:

• Albinism and sex allocation in Physa [5Nov18]

[6] Terwilliger, R. C. (1980)  The structures of invertebrate hemoglobins.  American Zoologist 20: 53 – 67.

[7] I feel sure that Physa acuta is found in more aquaria worldwide than Helisoma, but almost always as a pest.  I also see an awful lot of Melanoides tuberculata populations hiding in aquarium gravels … whether by accident or design is an interesting question.  See:

• What’s Out There? [9Oct17]

[8] I reviewed the gastropod fauna of local and online aquarium dealerships, including their planorbid component, in:

• Pet shop malacology [21Dec17]
• Snails by mail [24Jan18]

[9] No, not Wakendaw Lakes, which we have now featured twice in this blog, originally in [18Feb05] and again in [9Sept20].  The “Wakendaw Lakes” subdivision is in Mt Pleasant, which is a Charleston suburb East of the Cooper River (32.8289, -79.8569).  The control Helisoma trivolvis that I sent Cindy in 2018 (and indeed sent her for earlier experiments as well) was from Charles Town Landing, a state park very near my house West of the Ashley, on the other side of Charleston (32.8073, -79.9897).

[10] If you didn’t read it last month, you might enjoy:

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

[11] Dillon, R. T., T. E. McCullough, and C. E. Earnhardt. (2005)  Estimates of natural allosperm storage capacity and self-fertilization rate in the hermaphroditic freshwater pulmonate snail, Physa acuta.  Invertebrate Reproduction and Development 47: 111-115.  [pdf]

[12] Norton, C.G. & M.K. Wright (2019)  Strong first sperm precedence in the freshwater hermaphroditic snail Planorbella trivolvis.  Invertebrate Reproduction and Development DOI: 10.1080/07924259.2019.1630019.

[13] Norton, C.G. R.T. Dillon, Jr., K. Tweeten & N. Ezenagu (2019) What is a Species? Biological and Phylogenetic Data in the Genus Helisoma (Planorbella).  Simultaneous and Sequential Hermaphroditic Organisms Workshop, Salford, England.