Dr. Rob Dillon, Coordinator

Monday, July 6, 2020

The Return of Captain Lyon

“One man only remained behind.  It was Captain Sidney S. Lyon, of Jeffersonville, one of Indiana’s most gifted engineers.  As the Federal army moved away, he sat down upon a rock and waited.  Beside him lay a black, snake-like rope, the end running into the steep side of the mountain.  It was a fuse.  He had mined the mountain and filled the hollow with all the powder the fleeing army could spare…The tramp of the marching died away; the commissary stores were burning, and still he sat, as the night fell over the heights and the darkness filled the ravines.  Were the Confederates coming?  He heard the faint hoof-beats, the rumble of a great force of men coming from the Tennessee side.  There was the sparkle of a match, the splutter of powder, and a man fleeing down the mountain toward Kentucky for his life, and then…”
I honestly don’t know to what extent The Blowing of Cumberland Gap is true [1], but it does not matter, because it’s a great story, and I would recommend that you look up the Lyon family history [2] from google books and read pp 185 – 192, if you want to know how it turned out.  Or, if you would rather read my tenth (and final!) essay on the shell morphological variation and taxonomic confusion in the pleurocerid snails of the Tennessee/Cumberland in twelve months, soldier on below.
Sidney Smith Lyon (1808 - 1872)

In the fall and winter of 2016, a duller 154 years later, I spent a couple weeks in Frankfort, Kentucky, working with our good friend and colleague Ryan Evans on the freshwater gastropods of the Bluegrass State.  I had been surveying the region in preparation for the roll out of our new FWGO web resource for several years and, at that juncture, fancied myself familiar with most elements of the freshwater gastropod fauna of the Ohio River basin.  But what I found in KYDOW macrobenthic samples from little tributaries of the Green River, and even in some little creeks draining directly into The Ohio in western Kentucky, surprised me.  To the point that I can still remember it four years later.  Which at my age, is saying a lot.

I was already aware that P. simplex populations, of diverse shell morphology, extended across the entire drainage of the Tennessee/Cumberland from SW Virginia to Chattanooga, west through Tennessee and north into the Ohio River tributaries of Kentucky.  But my goodness!  Crawling around together with the P. simplex in the little creeks of western Kentucky, way out beyond Louisville, the KYDOW teams were also collecting pleurocerids indistinguishable to my eyes from Pleurocera troostiana, or arachnoidea, or spinella, or strigosa, or striatula, or whatever else people have called that pleurocerid bearing light, slender, striate shell with small body whorls in upper Tennessee River tributaries for almost 200 years.  The entire malacofauna of little creeks in Western Kentucky was indistinguishable from that of East Tennessee.

The shells of the particular population I was examining that afternoon were not costate, although several nearby populations were.  That is what especially struck me about those KYDOW samples, as I sat at the lab bench in Frankfort back in 2016, in addition to all the above.  I was as stricken by what I was not seeing, as what I was.  And this thought suddenly dawned on me.  If a pleurocerid species bearing a fat-smooth shell, like P. simplex, ranges through little creeks across four states, why can’t a pleurocerid species bearing a skinny-striate shell, like P. troostiana?

Western Kentucky or East Tennessee?
Let me back up for a bit of context.  Throughout Kentucky, and indeed through Middle Tennessee as well, streams of all sizes and descriptions are often choked with large and morphologically diverse populations of Pleurocera laqueata (Say 1829).  They bear shells with large body whorls that are sometimes striate but always, always costate.  I’d been looking a bottles-full of Pleurocera laqueata from central Kentucky all week.  Is it possible that some of those samples might be P. troostiana, slightly costate, not P. laqueata, slightly striate?

Have P. laqueata and P. troostiana been confounded in this part of the world for 200 years?  Might the nineteenth-century literature contain dozens of names for both, subsequently scrambled by synonymy?  If so, what are workers calling the tall-skinny-striate pleurocerids in Kentucky today [3]?

Following Branson’s [5] “Keys to the aquatic Gastropoda known from Kentucky” one finds four Goniobasis species “with longitudinal plicae” (i.e. striations) at any point in their shell growth: laqueata (Say 1829), curreyana (Lea 1841), costifera (Hald. 1841), and plicata-striata (Wetherby 1876).  The type shells borne by all four of these species are primarily costate, and I think the last three nomina will prove junior synonyms of Say’s laqueata.  Bookmark that question.  One day we’ll come back to it.

Reference to the primary literature, however, returns an excellent paper by Bickel [6] on the biology of pleurocerid populations he called “Goniobasis curreyana lyoni (Lea 1863)”.  I think that’s it.

Goniobasis lyoni then [9] and now.
Isaac Lea published a brief, Latinate description of Goniobasis lyonii – note two eyes in the original spelling [7] – in his ANSP Proceedings paper [8] “ordered to be published” on May 27, 1862 (although it says 1863 on the title page), followed by a more complete English description and figure in his ANSP Journal paper [9] “ordered to be published” on May 26, 1863.  We have touched on this pair of publications several times in recent months, featuring them in May.

Lea’s acknowledgement in the ANSP Journal paper [9] was: “I dedicate this with great pleasure to Mr. Lyon, Civil Engineer and State Geologist.”  War had not yet broken out between the states at the date of Lea’s writing, and Mr. S. S. Lyon had served as the topographer for the first (1854 – 57) Kentucky Geological Survey.

But war did come, carrying all American topographers along with it.  And my loyal readership will remember that it was Capt. Sidney Smith Lyon who stooped to capture two populations of rebel pleurocerids at Cumberland Gap in the summer of 1862, which he posted back behind the lines to Isaac Lea in Philadelphia.  Lea described that sample under four names in the smaller PANSP paper of 1863 [10] that kicked off this entire series of blog posts, way back in August of 2019.

I counted 20 hits to S. S. Lyon in Isaac Lea’s bibliography [11], first as Mr. Lyon, then as Capt. Lyon, and ultimately as Maj. Lyon, after August of 1863.  According to the family history published in 1907 [2], Lyon was an artist, a crinoid paleontologist, a naturalist, and singlehandedly saved the army of General George Morgan when it was surrounded at Cumberland Gap in September of 1862.  The account extracted at the top of the present essay was written by one Col. James Keigwin, and lovingly passed down to us by the Lyon family.

But back to the snails.  Lea’s description of Goniobasis lyonii noted that the shell was “very much drawn out” and “striate above.”  He did not mention costae but his figure (#156, reproduced above) shows light costation as well as light striation on the slender shell.  Lea gave the habitat as “Grayson County, Kentucky, S. S. Lyon.”  Its subsequent taxonomic history is Byzantine [13], but it was the substance of Bickel’s 1968 paper that lyonii should be resurrected as a subspecies of curreyana, which I don’t think it is [14], but I do give thanks for the resurrection.

Bickel restricted the lyonii type locality to Spring Fork Creek, a tributary of the Rough River in Grayson County, Kentucky.  He also reported populations in seven other small streams in four other counties: Breckinridge, Meade, Hardin, and Larue.  I sampled Spring Fork at three locations on the morning of 15May19 and was most disappointed by the quality of the environment, which in the last 50 years has declined to the status of muddy ditch, and by the population of pleurocerids dwelling therein, which has dwindled to zero.  Providentially, my database contained three other Grayson County sites at which lyonii populations had been collected by the KYDOW, and I found a decent population in a tributary of Big Run Branch, 5 km W of Leitchfield (37.5029, -86.3411).  See the example figured above.

Attributed to S. S. Lyon [12]
Pleurocerid populations bearing slender shells of the lyonii phenotype are not uncommon in small tributaries of the Tennessee, Cumberland, Green and Ohio Rivers in Kentucky west of Louisville and in Tennessee west of Nashville.  I cannot find any argument counter to the suggestion that lyonii (Lea 1862) is a junior synonym of troostiana (Lea 1838).  But let’s continue to recognize this set of populations with a subspecific nomen, Pleurocera troostiana lyonii, shall we?  And again, please review the definition of the word “subspecies” as adopted by the FWGNA from footnote [16] below.

Some populations of P. troostiana lyonii bear shells with light costation around their apex, rendering them effectively indistinguishable from P. troostiana perstriata, and some do not, rendering them indistinguishable from P. troostiana troostiana.  I struggled with the suggestion offered above.  Ultimately, I decided to preserve the S. S. Lyon patronymic in the pleurocerid canon more to protect the small (but not insignificant) literature associated with the taxon than to further any grand evolutionary hypothesis.  Besides which, I have grown rather fond of the gentleman.  He was not some pompous jackass sitting high-and-mighty behind a walnut desk in Philadelphia.  Capt. Sidney Smith Lyon did his duty.

Now at last, the time to summarize has arrived, woohoo.  Available from the link below is a pdf download entitled:

Here I have listed and figured all 13 of the specific and subspecific nomina I have synonymized under Isaac Lea’s Pleurocera troostiana since last August, together with type (or typical) localities and references.  I have not listed all the dozens of older synonyms under these nomina, as catalogued by Tryon and Goodrich. Quoting the latter, “I have not had the heart.”  This is FWGNA Circular Number 2 (July 6, 2020).


[1] Or maybe they’re lyon?  Sorry, I couldn’t resist.

[2] Lyon, S.E., et al. (1907) Lyon Memorial: Families of Connecticut and New Jersey, including records of the descendants of the immigrants Richard Lyon of Fairfield and Henry Lyon of Fairfield.  Detroit: William Granham Printing.  Pp 185 – 192.

[3] Back in November we reported that Isaac Lea described 505 species of pleurocerids.  Well, Dan Graf [4] cataloged approximately 500 more, contributed by other authors.  Those 1,005 names are a slough of despond into which I do not intend to fall.  So my approach for 40 years has been first to work out the biology, and then to work out the taxonomy.  First, my evolutionary intuition suggests that there are approximately 40 biological species of pleurocerids in North American waters, with another 20 subspecific nomina that may prove of some utility.  So second, I am trying to figure out what 60 names to call those populations or groups of populations.  Those 60 names may not be the oldest, nor the most familiar; they may be a compromise between age and modern use.  But if I live to be 107, I will never get to task #3, what the heck most of those other 945 names mean.

[4] Graf, D. L. (2001)  The cleansing of the Augean stables.  Walkerana 12(27): 1 - 124.

[5] Branson, B.A. (1987)  Keys to the aquatic Gastropoda known from Kentucky.  Trans. Kentucky Acad. Sci. 48: 11 - 19.

[6] Bickel, D.  (1968)  Goniobasis curreyana lyoni, a pleurocerid snail of west-central Kentucky. The Nautilus 82: 13 - 18.

[7] To quote The Eagles, “You can’t hide your lyon eyes,” pleural.  OK, I’ve got all the corny jokes out of my system, for now.

[8] Lea, Isaac. (1862) Description of a new genus (Goniobasis) of the Family Melanidae and eighty-two new species. Proc. Acad. Nat. Sci., Phila., xiv, pp. 262-272.

[9] Lea, Isaac (1863) New Melanidae of the United States.  Journal of the Academy of Natural Sciences of Philadelphia 5: 217 – 356.

[10] Lea, Isaac (1863) Descriptions of fourteen new species of Melanidae and one Paludina.  Proceedings of the Academy of Natural Sciences of Philadelphia 15: 154 – 156.

[11] Scudder, N. P. (1885)  Bibliographies of American naturalists – II. The published writings of Isaac Lea, LL.D.  Bull. US National Museum 23: 1 – 278.

[12] For more about the “White Horse” painting attributed to S. S. Lyon, see:
Clark County Museum looking for help to restore historic painting.  News and Tribune (Clark County, Indiana).  February 12, 2018. [html]

[13] I quote Bickel [6] verbatim: “This animal is Goniobasis lyoni Lea, 1863, a species that Tryon (1865) placed in the synonymy of Goniobasis glauca (Anthony).  It was subsequently transferred along with G. glauca to the synonymy of Goniobasis athleta (Anthony) by Tryon (1873), and Goodrich (1940) shifted it to the synonymy of Goniobasis laqueata (Say).  Goniobasis lyoni is a form of Goniobasis curreyana (Lea) and is distinct enough to merit recognition.”

[14] It is hard for me to understand why Dave Bickel thought lyonii was a subspecies of curreyana.  Lea’s (1843) figure clearly depicts Melania curryana as a laqueata-type, bearing an aperture “about one-third the length of the shell,” not a troostiana-type, with aperture smaller.  And Lea specifically stipulated [15] that the shell of curreyana “is without striae,” focusing instead on the “large and strong folds.”  Lea’s (1841) Melania curreyana is clearly a junior synonym of laqueata (Say 1829) and has nothing to do with his Goniobasis lyonii of 1862.

[15] Lea, Isaac (1843)  Description of New Fresh Water and Land Shells.  Transactions of the American Philosophical Society 8: 163 – 250.

[16] Subspecies are populations of the same species in different geographic locations, with one or more distinguishing traits.  For elaboration, see:
  • What is a subspecies? [4Feb14]
  • What subspecies are not [5Mar14]