Editor’s Note – This the fourth installment of a five-part series on Pleurocera laqueata, P. troostiana, and hybridization between them in small streams of Kentucky, Tennessee, and North Alabama. If your interest in the evolution of the North American Pleuroceridae is serious enough to have dropped you this deep into so dismal a swamp, and you have not previously read my posts of [18Sept24], [15Oct24] and [12Nov24], go back and do so now. We will wait for you.
Calvin Goodrich [1] divided the Goniobasis species of the Tennessee, Cumberland, and Ohio River systems into six groups [2]. Prominent among those was a “Group of Goniobasis laqueata,” with ten species and six subspecies, and a “Group of Goniobasis catenaria” with eight species and one subspecies. Unsurprisingly, most of the nomina in that former group are synonyms of Pleurocera laqueata (Say 1829), and most of the latter group synonyms of Pleurocera troostiana (Lea 1838).
But because P. laqueata and P. troostiana hybridize, the distinction between Goodrich’s two groups has never been clear. Burch [3] moved three species with two subspecies from Goodrich’s Group of Goniobasis laqueata to his understanding of the “Elimia catenaria Group” and separated one species/subspecies pair from Goodrich’s laqueata group (the “Elimia acuta Group”) as entirely distinct.
So, working alphabetically, this month we will review the first twelve of the 10 + 6 + 8 + 1 = 25 pleurocerid nomina from the Ohio, Cumberland and Tennessee allocated by Calvin Goodrich to his Groups of Goniobasis catenaria and Goniobasis laqueata combined.
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| USNM119088 (14.9 mm), MCZ50236 (21.1 mm), USNM119217 (13.5mm) |
The vast majority of these were described by our old buddy Isaac Lea [4], in eight separate papers and monographs published between 1831 and 1868. Lea described seven of the species we will review over the next two months (as “Melania”) in brief Latinate form in the Proceedings of the American Philosophical Society of 1841 [5], following with more complete English descriptions and figures in the APS Transactions of 1843 [6]. He disgorged an additional dose of seven brief Latinate descriptions (as “Goniobasis”) in the Proceedings of the Academy of Natural Sciences of 1862 [7], following with complete descriptions and figures in the ANSP Journal of 1863 [8]. Lea’s descriptions of the third set of seven species were scattered in other journals at other times.
This catalog may get a bit tedious at times, I’m afraid, involving a lot of rather dry library scholarship, and to be quite frank, is not the kind of thing I am especially good at, not having been blessed with the lawyerly frame of mind necessary to build any reputation in the marble halls of zoological nomenclature. It’s a service, I suppose.
So, for a spoonful of sugar, last month I traveled up to Washington to see our good friend Ellen Strong of the USNM. Ellen and her obliging staff set aside for me Isaac Lea’s type specimens [9] for 20 of the species that Goodrich included in his groups of catenaria and laqueata from the greater Ohio drainage. This is the first time that photos of any of those types have ever been published, as far as I am aware.
And I contacted our good buddy Gonzalo Giribet up at the MCZ Harvard, and he and Ms. Jennifer Trimble agreed to add type specimens of Conrad’s nassula, Anthony’s arachnoidea, and Wetherby’s plicata-striata to their (rather lengthy) “imaging queue.” And our friends at the ANSP, already on the ball, had previously uploaded and made available to the public a nice photo of Haldeman’s costifera. Bottom line, over the next two months, we will publish fresh photos of type material for 24 of the 25 catenaria/laqueata group species in habiting the Ohio, Cumberland, and Tennessee River systems. And offer a coherent, modern hypothesis for both their evolutionary and their taxonomic relationships. Here we go:
Acuta. First, we must be very clear about what the pleurocerid snail that Isaac Lea described as Melania acuta is not. It is not that well-known inhabitant of rivers and streams of the Ohio, Great Lakes, and upper Mississippi drainages described as “Pleurocera acuta” by C.S. Rafinesque [11] in 1831, monographed in loving detail by Dazo [12] in 1965. Rafinesque’s Pleurocera acuta was lowered to subspecific status under Pleurocera canaliculata by Dillon [13] in 2013.
Completely independent of whatever Constantine Smaltz Rafinesque was discovering and publishing in the early 19th century, on May 7, 1830 Isaac lea read a paper at a meeting of the American Philosophical Society in Philadelphia describing “Melania acuta” from the “Tennessee River, Prof. Vanuxem” bearing a shell whose “delicate form, furnished with undulations and transverse lines, will easily distinguish it.” Lea’s little 1:1 figure is reproduced below.
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| From Lea [14], Anthony [20], Lea [22], Reeve [24] |
A reading is not a publication, however. The front page of Volume 4 of the Transactions of the American Philosophical Society, in which Lea’s paper was ultimately published [14], clearly states 1834. N.P. Scudder [15] argues, however, that Lea’s paper was “issued in the latter end of 1831, and acknowledged by correspondents as received in that year, PANSP 7:243.” Tryon [16] does not hazard a guess on Lea’s publication date, Goodrich [1] suggests 1830 and both Burch [3] and Graf [10] concur with Scudder’s 1831.
So, the bottom line is that Rafinesque’s acuta and Lea’s acuta seem to have been published simultaneously. And since Lea’s acuta was reassigned to Goniobasis by Tryon [16], and then re-reassigned to Elimia by Burch [3], and then both Goniobasis and Elimia folded under Pleurocera by Dillon [17], today we have two Pleurocera acutas, both described in 1831, meaning entirely different things.
Rafinesque’s acuta became prominent, however, while Lea’s acuta receded into obscurity. A big part of the reason is that Isaac Lea’s type locality was vague. Goodrich [18] speculated that the that the “Tennessee River” from which Vanuxem sampled that first specimen of Lea’s acuta must have been in North Alabama, where specimens matching his description “have been taken at Muscle Shoals by Messrs. Hinkley and Smith.” That malacologically rich section of the Tennessee River is long inundated and much lamented [19]. Goodrich also reported collections from the Flint River, the Elk River, and Piney Creek, but of course, tributaries are a poor substitute for the main river itself.
An image of the type specimen (USNM119088) was reproduced way up at the top of this blog post. Rather than join the speculation on where that shell might have been collected, or whether the population of pleurocerid snails including the individual from the back of which it was snatched almost 200 years ago might have been reproductively isolated from any of the biological species of pleurocerids we recognize today, I will simply suggest that Melania acuta Lea 1831 is a junior homonym of Pleurocera acuta Rafinesque 1831. RIP Melania (aka Goniobasis, aka Elimia) acuta.
Arachnoidea. John G. Anthony [20] described Melania arachnoidea from “a small stream emptying into the Tennessee River near Loudon, Tennessee” in 1854. Goodrich [1] considered it a valid species in his Group of Goniobasis catenaria, as did Burch [3] in his Elimia catenaria Group. We consider the nomen a junior synonym of Pleurocera troostiana troostiana (Lea 1838).
For our rationale, together with an image of a modern topotype, see Dillon [21] pp 41 – 49 or my essay of [7Jan20]. See above for an image of a lectotype (MCZ50236) and a reproduction of Anthony’s original 1:1 figure. We measured and scored a sample of N = 30 shells from Anthony’s arachnoidea type locality near Loudon for our troostiana regression analysis two months ago [15Oct24].
Castanea. Isaac Lea’s brief Latinate description of Melania castanea (Maury County, Tenn. Thomas H. Dutton) was published in 1841 [5], with a more complete English description and figure following in 1843 [6]. Last month [12Nov24] I reproduced Lea’s original 1843 figure, concurring with Goodrich’s [1] suggestion that castanea is a valid subspecies Pleurocera laqueata castanea (Lea 1841), and advancing the hypothesis that pleurocerid populations bearing shells of that distinctive morphology are hybrids between P. laqueata and P. simplex. A fresh image of the holotype, USNM119217, was reproduced in the figure that opened this essay way up above.
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| USNM121480 (10.2 mm), ANSP27434 (18.3 mm), USNM119021 (19.3 mm), USNM118463 (14.1 mm) |
Clavula. Goniobasis clavula was described from “Jackson Co, Alabama, Dr. Spillman” by Isaac Lea [22] in 1868. That county, in the extreme NE corner of Alabama, lies entirely within the Tennessee River drainage. The nomen was demoted to subspecific status under Goniobasis acuta by Goodrich [1, 18] and placed in the Group of Goniobasis laqueata. Burch [3] agreed with Goodrich about the subspecific relationship but transferred clavula along with its parent into a separate Elimia acuta Group.
Both Lea’s [22] original figure and a fresh image of the holotype (USNM121480) are reproduced above. The type specimen is subadult, very slender, demonstrating both striation and plication, becoming obsolete on the body whorl. We consider the nomen a junior synonym of the hybrid Pleurocera troostiana perstriata (Lea 1853).
Costifera. Melania costifera was described in 1841 from “Hennepin, Illinois” by S. S. Haldeman [23]. The nomen was considered to represent a valid species by both Goodrich and Burch, in their Groups of Goniobasis laqueata and Elimia laqueata, respectively. No figure was provided originally, but Haldeman’s written description “having numerous, spiral, elevated lines, crossing a series of curved ribs, on all the whorls,” together with the slender figure subsequently published by Reeve [24], reproduced above, sound very much like P. troostiana lyonii.
Haldeman’s original type shell (ANSP27434) is still held in the ANSP collection today, however, its image thoughtfully made available online by our friends in Philadelphia. And that image, as reproduced above, suggests that the “spiral, elevated lines” are negligible, and the body whorl relatively large, as typical for Pleurocera laqueata laqueata.
In such a situation, where the published figure and the type shell are strikingly different, it would be nice to refer to a modern topotypic collection. Alas, my review of the online catalog at the Illinois Natural History Survey returned no modern records of costifera, laqueata, troostiana, or any pleurocerid bearing a shell with plications or striations of any sort within 250 miles of Hennepin [25]. Absent a tiebreaker, therefore, the actual type shell as held by the ANSP must take precedence over the Reeve’s 1860 figure. Melania costifera (Hald 1841) would appear to be a junior synonym of Pleurocera laqueata laqueata (Say 1829).
Costulata. Melania costulata was described in 1841 by Isaac Lea [5] from the “Barren River, Kentucky.” His 1843 figure [6] is reproduced below. Goodrich [1] recognized the nomen as a subspecies of Goniobasis laqueata, as did Burch [3] of Elimia laqueata.
Lea wrote, “In its general characters this species resembles M. laqueata Say. It may be distinguished in its being of less diameter and being more slender.” The holotype shell (USNM119021) as freshly figured above is indeed a bit more slender than typical for laqueata. But it demonstrates strong striations (not noted by Lea) as well as plications, extending down to include the body whorl. We consider costulata a junior synonym of the hybrid taxon Pleurocera troostiana edgariana (Lea 1841).
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| From Lea [6], Lea [6], Lea [8]. |
Crispa. Isaac Lea [7] described Goniobasis crispa from “Florence, Alabama” in 1862. The nomen was lowered to subspecific status under G. perstriata by Goodrich [1, 18] and placed with its parent in the Group of Goniobasis laqueata. Burch [3] concurred with the demotion, but not the placement, transferring “Elimia perstriata crispa” to his Elimia catenaria Group. We consider the nomen a junior synonym of Pleurocera nassula (Conrad 1834). See Dillon [21] pp 61 – 71 or my essay of [10May20] for a copy of Lea’s [8] original figure. A fresh image of the holotype (USNM118463) is collected above.
Curreyana. Just as was the case of Melania costulata, Melania curryana was described by Isaac Lea [5] from the “Barren River, Kentucky” in 1841. Lea’s 1843 figure of curreyana [6] is reproduced next to his figure of costulata above. And again, as in M. costulata, Goodrich [1] recognized M. curryana as a valid nomen in his Group of Goniobasis laqueata, as did Burch [3] in his Elimia laqueata Group.
Unlike M. costulata, however, Graf [10] was unable to find any type material for curreyana in the USNM. It would appear that Lea’s 1841 written description, together with his 1843 figure, are all we have for evidence today.
Lea wrote that the shell of M. curreyana was “Remarkable for large and strong folds,” adding “It is without striae, and the body whorl is smooth, except near the suture.” Those contemporary observations, together with Lea’s figure of a shell absent any apparent striation, combine to suggest strongly that M. curreyana (Lea 1841) is a simple junior synonym of Pleurocera laqueata laqueata (Say 1829).
Decampii. Isaac Lea [26] described Goniobasis decampii from “Huntsville, Alab.” in 1866. He apparently intended to include the Latinate description in his paper of Mayish [27] 1863, because in his follow-up paper of 1866 he stated that his original description had been published three years earlier, but it was not.
The nomen was lowered to subspecific status under G. perstriata by Goodrich [1, 18] and placed with its parent in the Group of Goniobasis laqueata. Burch [3] concurred with the demotion, but not the placement, transferring “Elimia perstriata decampii” to his Elimia catenaria Group. We consider the nomen a junior synonym of the hybrid taxon Pleurocera troostiana perstriata (Lea 1853).
For our rationale, together with a copy of Lea’s [26] original figure, see Dillon [21] pp 61 – 71 or my essay of [10May20]. A fresh image of the very slender holotype shell (USNM118967), bearing light striations and plications on its upper whorls only, is collected below.
Edgariana. Isaac Lea [5] described Melania edgariana from “Cany Fork, Tenn.” in 1841. Tryon [16] synonymized the nomen under Conrad’s (1834) nassula [28] but Goodrich [1] resurrected it as a valid species in his Group of Goniobasis laqueata. Burch agreed on the specific status but transferred it to his Elimia catenaria Group. We consider the nomen valid at the subspecific level, Pleurocera troostiana edgariana (Lea 1841), identifying laqueata/troostiana hybrids with strong sculpture on the body whorl.
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| USNM118967 (17.0 mm), USNM118423 (19.0 mm), USNM118959 (17.5 mm) |
Interveniens. Isaac Lea [7] briefly described Goniobasis interveniens from “North Alabama, Prof. Tuomey” in 1862, with a more complete description and figure following in 1863 [8]. His original 1:1 figure and an image of the holotype (USNM118959) are reproduced above. Both Goodrich [1, 18] and Burch [3] considered interveniens a valid and distinct species in their Groups of Goniobasis laqueata and Elimia laqueata, respectively. We are at a loss to find any distinction between Lea’s interveniens and Thomas Say’s laqueata whatsoever, considering Goniobasis interveniens (Lea 1862) a simple junior synonym of Pleurocera laqueata laqueata (Say 1829).
Laqueata. Melania laqueata was described by Thomas Say in 1829 from “Dr. Troost in Cumberland River” [29]. No original type material seems to have survived, although Say’s written description and figure were sufficient to establish it as the type for both Goodrich’s Group of Goniobasis laqueata and Burch’s Elimia laqueata Group.
Pleurocera laqueata (Say 1829) is the oldest name for a distinct, valid, biological species of pleurocerid snail widespread in rivers and streams of Middle Tennessee, North Alabama, and southern Kentucky. We recognize three subspecies: the big river alveare (Conrad 1834) and the laqueata/simplex hybrid castanea (Lea 1841), as well as the typical (s.s.). For a complete review, illustrated with a copy of Say’s [29] original figure and images of several modern topotypic shells, see my essay of [18Sept24].
Okay, twelve down. Many of you, I feel sure, will have heard that saccharine story about the young girl who finds a million starfish washed up on the beach, and begins to toss them back, one at a time. Along comes a man and asks her how she could possibly hope to save a million starfish. And she flips another starfish into the sea and replies, “Well, I saved that one.”
So Dan Graf [10] catalogued over 1,000 pleurocerid nomina at the specific or subspecific level, washed up on the beach like starfish. In this month’s essay we flipped three nomina back into the ocean (castanea, edgariana, laqueata), bagged nine others, and threw them into the dumpster. Next month we’ll dispatch 14 more, one way or the other.
Notes:
[1] Goodrich, C. (1940) The Pleuroceridae of the Ohio River drainage system. Occasional Papers of the Museum of Zoology, University of Michigan 417: 1-21.
[2] Plus a seventh set of “unknowns” and an eighth set he
identified as “invasions” from the Alabama system.
[3] 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).
[4] For a brief biographical sketch of Isaac Lea, and a
review of his contribution to our modern understanding of freshwater gastropod
evolutionary biology, see:
- Isaac Lea Drives Me Nuts [5Nov19]
[5] Lea, Isaac (1841) Continuation of Mr. Lea's paper on New
Fresh Water and Land Shells. Proceedings
of the American Philosophical Society 2: 11 – 15.
[6] Lea, Isaac (1843) Description of New Fresh Water and
Land Shells. Transactions of the
American Philosophical Society (New Series)
8: 163 – 250.
[7] Lea, Isaac (1862) Description of a new genus
(Goniobasis) of the Family Melanidae and eighty-two new species. Proceedings of
the Academy of Natural Science of Philadelphia 19: 262 – 272.
[8] Lea, Isaac (1863) New Melanidae of the United
States. Journal of the Academy of
Natural Sciences of Philadelphia (New Series) 5: 217 – 356.
[9] All 20 of these specimens are labeled “holotype” in the
USNM collection. Graf [10] considered
most of them lectotypes, but I am not going to second-guess the USNM.
[10] Graf, D. L. (2001) The cleansing of the Augean
stables. Walkerana 12(27): 1 - 124.
[11] Rafinesque, C.S. (1831) Enumeration and account of some
remarkable natural objects in the cabinet of Prof. Rafinesque, in
Philadelphia. Self-published, 4 pp.
[12] Dazo, B.C. (1965) The morphology and natural history of
Pleurocera acuta and Goniobasis livescens (Gastropoda: Cerithiacea:
Pleuroceridae). Malacologia 3:1-80.
[13] Dillon, R. T., Jr., S. J. Jacquemin & M. Pyron
(2013) Cryptic phenotypic plasticity in populations of the freshwater
prosobranch snail, Pleurocera canaliculata.
Hydrobiologia 709: 117-127.
[html] [pdf] For more, see:
- Pleurocera acuta is Pleurocera canaliculata [3June13]
- Pleurocera canaliculata and the process of scientific discovery [18June13]
[14] Lea, I. (1831/34) Observations on the naiads, and
descriptions of new species of that and other families. Transactions of the American Philosophical
Society (New Series) 4: 63 – 121.
[15] Scudder, N. P. (1885) Bibliographies of American
naturalists – II. The published writings of Isaac Lea, LL.D. Bulletin of the US National Museum 23: 1 –
278.
[16] Tryon, G. W. (1873) Land and Freshwater shells of North
America Part IV, Strepomatidae.
Smithsonian Miscellaneous Collections 253: 1 - 435.
[17] Dillon, R. T., Jr. (2011) Robust shell phenotype is a
local response to stream size in the genus Pleurocera (Rafinesque, 1818).
Malacologia 53: 265-277. [pdf] For a
review, see:
- Goodbye Goniobasis, Farewell Elimia [23Mar11]
[18] Goodrich, C. (1930)
Goniobases of the vicinity of Muscle Shoals. Occasional Papers of the Museum of Zoology,
University of Michigan 209: 1 – 25.
[19] The TVA closed Wheeler Dam in 1936 and Pickwick Dam in
1938, creating a pair of reservoirs that covered the North Alabama shoals of
the Tennessee River under 100 miles of slackwater and muck. For my own personal lament, see the latter
half of:
- The Union in Tennessee! [15Aug23]
[20] Anthony, J.G. (1854) Descriptions of new fluviatile
shells of the genus Melania Lam., from the western states of North
America. Annals of the Lyceum of Natural
History of New York 6: 80 -132.
[21] Dillon, R.T., Jr. (2023b) The Freshwater Gastropods of
North America Volume 6, Yankees at The Gap, and Other Essays. FWGNA Project, Charleston, SC. [publications]
[22] Lea, Isaac (1868) New Unionidae, Melanidae, etc.,
chiefly of the United States. Journal of
the Academy of Natural Sciences of Philadelphia (New Series) 6: 303 – 343.
[23] Haldeman. S. S. (1841) A monograph of the Limniades and
other freshwater univalve shells of North America. Volume 2.
[24] Reeve, L. A. (1860) Conchologia Iconica, or,
Illustrations of the shells of molluscous animals. Volume 12, Plate 56.
[25] The INHS collection does hold four historic records of
“Elimia” costifera from a creek in Hardin County, bordering the Ohio River
about 250 miles south of Hennepin. The
University of Michigan also holds one historic lot of Goniobasis costifera
(UMMZ 241604) from Hardin County. That
is simply too far away from Hennepin to have any bearing on this question.
[26] Lea, Isaac (1866) New Unionidae, Melanidae, etc.
chiefly of the United States. Journal of
the Academy of Natural Sciences of Philadelphia (New Series) 6: 113 – 187.
[27] 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. Lea apparently read his paper in
May of 1863, and “May” is printed on the bottom of the published pages, but the
front of the published volume says, “June and July, 1863.”
[28] Conrad, T. A. (1834) New Fresh Water Shells of the
United States, with coloured illustrations, and a monograph of the genus
Anculotus of Say; also A synopsis of the American naiades. Philadelphia, Judah Dobson. 76 pp, 8 plates.
[29] Say, T. (1829) Descriptions of some new terrestrial and
fluviatile shells of North America. New
Harmony Disseminator of Useful Knowledge 2(18): 275 – 277.
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