Dr. Rob Dillon, Coordinator

Thursday, November 19, 2015

FWGNA Version 11/15

We are pleased to announce that a new version Nov15 of the FWGNA website is now on line and open for business.  This is not a new operating system by any means - just an incremental point-one upgrade.  But certainly worth a notice, nonetheless.  Click the FWGNA logo at right to check it out.

The refreshed site is based on 12,211 records collected from the Atlantic drainages of our nine-state coverage area [1], up 6.5% from the 11,471 records upon which our previous Oct13 version was based.  Most of the 740 new records come from South Carolina, for which we owe a debt of gratitude to Jim Glover, David Eargle, and Justin Lewandowski of the SC Department of Health and Environmental Control.  The Atlantic drainage fauna has now increased from 67 species to 69, with the addition of (apparently invasive) populations of Melanoides tuberculata and Pyrgophorus parvulus [2].  More about that next month.

All the statewide tabulations (GA, SC, NC, VA, and Mid-Atlantic) have been at least slightly updated, as has the overall FWGNA Synthesis for the Atlantic drainages together [3].  There are a few changes in the FWGNA incidence ranks for the rarer (and hence less stable) species, but nothing drastic.

We’ll keep in touch,


[1] We have not updated our FWGTN survey of the Tennessee River drainages since 2011.  That chore is long overdue, we must confess.

[2] The total number of species covered by the entire FWGNA site is up from 87 to 89.

[3] The fit of the 69-species distribution of commonness and rarity to a lognormal model continues to worsen, now down to a Shapiro-Wilk W = 0.957 (p = 0.019).

Monday, November 9, 2015

To Only Know Invasives in My General Vicinity ...

A couple years ago I received a cordial email from a young lady working with a natural resources agency in a big Midwestern state.  She was looking for help developing a key to identify invasive freshwater gastropods in her general vicinity – not the native species, just the important ones.  Here’s what I suggested:

1a) Operculum present . . . (2)
1b) Operculum absent . . . never mind.

2a) Really big! . . Potentially devastating economic impact.
2b) Little . . . (3)

3a) Only a few of ‘em . . . screw it.
3b) Bazillions of ‘em! . . . Potentially devastating economic impact.

So last month we reviewed the USGS Nonindigenous Aquatic Species database [1], an open and earnest federal effort to monitor the distribution and spread of invasive species in the nation’s lakes and rivers, including (at this writing) 42 freshwater gastropods.  This month we’ll broaden our field of view, but sharpen our focus, looking toward state-level invasive species monitoring programs.

State interest in invasive species is typically directed rather narrowly toward perceived threats to agriculture or commerce or human health.  At the very least, the doggone thing from China or wherever it says it came from has got to make itself a nuisance.  So for example, my home state of South Carolina doesn’t really care about the huge populations of invasive viviparids in our reservoirs, unless (I suppose) there’s a significant die-off, and somebody complains about the stink [2].  Which sounds like a problem solving itself.  The South Carolina DNR does, on the other hand, care about our invasive populations of Pomacea, primarily because of its potential to host the rat lungworm [3].  More about that in a future post.

Mud Snail Poster - CaliforniaThe states of California, Oregon and Washington all care about the current range and future spread of Potamopyrgus antipodarium, the “New Zealand Mud Snail” because, to quote the Oregon Department of Fish & Wildlife’s modest web page [4], “there is concern [about] devastating effects to recreational fishing.”  So for more information, Oregon directs its citizens to the New Zealand Mud Snail page at the USDA National Invasive Species Information Center, from whence they might surf over to the USGS-NAS database and report their observation. 

California has developed a larger page on Potamopyrgus, featuring the snail on one nice, colorful poster and one blunt, scary poster (left), both available for download [5].  In addition to mentioning the USGS-NAS database, citizens of California who have observed Potamopyrgus are asked to call or email their Department of Fish & Wildlife directly.

Like California, the State of Washington also has a nice web page devoted to Potamopyrgus, with a downloadable fact sheet, although no keen posters [6].  There is, however, a “Report online” link from the Washington Potamopyrgus page where a citizen might open a (vanilla) online reporting form to send a potential sighting to the Washington DNR.  Or one might elect to download a “WA Invasives” app for one’s smartphone.  Impressive.

The point I’m making here, however, is that none of these three states apparently gives a rip about the populations of European Lymnaea (Radix ) auricularia which have spread all over the American West in the last 100 years, but apparently have not risen to the level of a threat, or a pest, or even a “nuisance.”  You’re just a fat little brown snail.  No smartphone app for you.

There are exceptions to this general rule.  Back in 2011 we featured a “Citizen’s Watch” initiative in the state of Wisconsin [7], broadly charged with monitoring invasive species of all sorts, as well as general aspects of the physical environment, water quality, and so forth, for specific lakes.  The Maine Volunteer Lake Monitoring Program [8] also features an invasive species component which, although focused on aquatic weeds, includes a mechanism to report “suspicious” aquatic organisms of all phyla.  Click the header below for the entire form:

 Maine Suspicious Organisms Report

The high end of invasive species monitoring programs seems to be occupied by a set of nine states (and one Canadian Province) who have adopted a NatureServe system called “ImapInvasives.”  This is an online system that rivals (and in many respects, surpasses) the USGS-NAS database in its scope and versatility.  Open the link below in a new window and check it out, if you’re not already familiar with the program.

If you click the “Login/Maps” button at the top of the iMapInvasives home page you will find a list of the ten states and provinces currently subscribing, from whence you might be tempted to follow links to try the system out.  ImapInvasives is designed as a monitoring system for exotic biota of all sorts – weeds, bugs, slugs, stoats, goats, giraffes, Giselles, and especially rabbits.  Only four states list freshwater gastropods on their public maps at present: Maine (Bellamya), Pennsylvania (Bellamya, Potamopyrgus), Oregon (Bellamya, Potamopyrgus [9], Melanoides), and Arizona (Bellamya, Melanoides, L. auricularia).

The “public maps” viewable from the several states listed above are disappointingly low in their resolution – returning just county or watershed (8-digit HUC) of record, not the precise locality.  They also show only a subset of the species actually tracked, in some cases.  To see a detailed map, or access locality data, or contribute fresh data to these systems, one must be a registered user.

Over the last couple years I have developed a cordial relationship with Ms. Amy Jewitt, the invasive species information assistant working for the Pennsylvania Natural Heritage Program.  She offered to register me for the Pennsylvania site, and I can report that it is as easy to use and informative on the inside as the USGS-NAS system is on the outside. 
Bellamya chinensis on iMapInvasives
Pennsylvania actually tracks the entire rogue’s gallery of invasive freshwater gastropods in its iMapInvasives system as implemented for registered users, including Bithynia and Viviparus as well as Bellamya and Potamopyrgus.  The Bellamya are sorted correctly (I have reason to think) into 33 records of chinensis and 18 records of japonica, with just one single record of “species uncertain.”  The reason I have reason to think the Pennsylvania identifications are correct is that most of their records are ones I forwarded to Ms. Jewitt from the FWGNA database back in 2013.  And she continues to send me jpegs for identification, as new sightings are reported.

So how well-coordinated are the state and federal efforts?  One of my prompts to launch the present series on invasive species came in late September when I happened to receive emails from both Ms. Jewitt and Mr. Matt Cannister, a contractor working with the USGS office in Gainesville, both with attached Bellamya jpegs.  Mr. Cannister’s response to my question was quite positive: “there is usually a high level of information sharing between state and federal biologists and ourselves here at NAS.”  Ms Jewitt was more guarded, albeit hopeful:
“As of right now, we do not have any of the USGS data in PA iMap and we have not sent any of our data to them, though we hope to change this in the very near future.  There is one big task that needs to happen on our end first before we can begin data sharing with them; however, once that happens, the PA iMap database will certainly have much more useful information to provide.”
I should conclude this month’s essay by re-assuring everybody that I thumbs-up-like online governmental programs to monitor invasive species.  They are a mixed blessing for the FWGNA project, which is, after all, an effort to survey of an entire fauna, and subject to the phenomenon I identified last month as invasion-biased oversampling.  But nothing I have written in my last couple posts is intended to reflect negatively on the hardworking public servants at any level, state or federal, who are doing their best to deal with the rising tide of exotic species inundating our shores.

Budgets are small and personnel are few, and I certainly understand why natural resource agencies must pick (at most!) a couple invasive freshwater gastropods that seem the most intimidating, and (on the flip side) a couple nominally “endangered” freshwater gastropods that seem the most pathetic, and let the other 95% of our North American freshwater gastropod fauna fend for itself.  They’re just little brown snails.


[1] To Only Know Invasives [16Oct15]

[2] Just Before the Bust [5Aug14]

[3] Pomacea Spreads to South Carolina [15May08]
     Two Dispatches from the Pomacea Front [14Aug08]
     Pomacea News [25July13]

[4] Oregon Department of Fish & Wildlife [New ZealandMud Snails]

[5] California Dept of Fish & Wildlife [New Zealand Mud Snails]

[6] Washington Invasive Species Council [New Zealand MudSnails]

[7] Dispatches from the Viviparid Front [12Sept11]

[8] Maine Volunteer Lake Monitoring Program [html]

[9] Alert readers will notice that I just reviewed the Oregon Potamopyrgus page about six paragraphs earlier in this essay, and said nothing about iMapInvasives.  Yep, strange but true.  I cannot find a link from any agency of the State of Oregon to iMapInvasives.  Maybe this is just an oversight?  But it is consistent (I am afraid) with the general inhospitality of the iMapInvasives system.

Friday, October 16, 2015

To Only Know Invasives

I’ve never compiled any statistics, but it is my impression that the most common category of inquiry I find delivered to my email inbox on any long-term basis probably bears the modifier “invasive” on the subject line.  Such messages are usually requests for identification of putatively exotic freshwater gastropods, with jpeg images attached.  Sometimes these inquiries come from professional biologists working with agencies, and other times just from ordinary concerned citizens.  I always try to help.

So a couple years ago I receive a variant of the typical email described above, from a NOAA biologist in the Great Lakes area.  The attached jpeg image depicted a couple beach worn shells of the common pleurocerid Pleurocera semicarinata livescens.  And in the body of his message the biologist confessed, amidst other routine background matter, “I really only know the invasives.”  He was quite certain that these freshwater gastropods were not Bithynia, or Bellamya, or Potamopyrgus.  But he didn’t know what they were.

And this struck me as a sad way of looking at the world.  One is reminded of a clinical practitioner who never leaves the hospital – only knowing the sick, never meeting the well. 

But in a larger sense, the existence of a biologist, or an agency, or indeed multiple governmental agencies, who “only know invasives” has become an article of public policy in recent years.  The Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 established a body called the “Aquatic Nuisance Species Task Force,” with representation from 13 federal agencies, which in turn established a National Nonindigenous Aquatic Species Information Center “to collect, analyze, and disseminate information about the presence and distribution of nonindigenous aquatic species and their effects.”  That Center is currently located at the US Geological Survey’s Southeast Ecological Science Center in Gainesville, Florida [1].

The most visible product of the USGS Information Center has been the development of the Nonindigenous Aquatic Species database, which can, under some circumstances, be a useful resource, if you understand its limitations, which are extensive.  Do open this site in a new window and check it out, if you’re not familiar with it already:

The USGS-NAS tracks a staggering 44 species (or categories of species) of freshwater gastropods: 11 ampullariids, 8 viviparids, 3 thiarids, 7 miscellaneous prosobranchs, 7 planorbids, 5 physids, and 3 lymnaeids.  Of this extensive list only 32 are exotic; 12 species or categories are native to North America, but have expanded their ranges so recently or so dramatically, possibly by human agency, as to attract the attention of The Feds.  Current distributions of these 44 species are displayed as good quality dot maps which are zoomable and clickable, to see the underlying records.  Public users are allowed to add records to the database through a process that is not terribly difficult or onerous, which certainly has a downside, but which (on the whole) I think is good.

The site is, however, a taxonomic mess.  It reminds me of my son’s bedroom, when he was nine years old.  Stuff is thrown around everywhere, and it would be very difficult to find anything you might want in there, if (hypothetically) you wanted to find it, and most of the stuff you can see when you pass by the open doorway is just junk, and should be thrown out.

USGS-NAS chinensis
For example, the USGS-NAS collects data on four separate categories of the Asian Mystery Snail: Cipangopaludina japonicaCipangopaludina chinensisCipangopaludina chinensis malleata, and "Cipangopaludina species.”   The most current science suggests, however, that just two species of mystery snail have been introduced to North America, best identified as Bellamya japonica and Bellamya chinensis.  It is very difficult for laymen, or indeed most field biologists, to distinguish japonica from chinensis.  In fact, both of the thumbnail photos of shells adorning the clickboxes for chinensis and japonica on the USGS-NAS website depict chinensis [2].

I really don’t trust the species-level identifications upon which any of the four “Cipangopaludina” maps are based, and would advocate combining all those data into a single map that simply shows “Bellamya species.”   If the mission of the USGS-NAS database is indeed to disseminate information about the “distribution of nonindigenous species and their effects,” B. chinensis and B. japonica are ecologically equivalent [3], and combining them would make sense.

USGS-NAS "japonica"
(not, actually)
The situation is much more complicated in the Ampullariidae, I fear.  It is not entirely clear how many exotic species of Pomacea have been introduced into US waters, but the best hypothesis at this writing is probably four: Pomacea maculata (aka insularum) which is the most common, Pomacea canaliculata (bona fide) which is very similar but more rare, Pomacea diffusa (aka bridgesii) which is smaller and not as voracious, and Pomacea haustorum, which is much larger and rare.  I myself am not sure I could distinguish maculata from canaliculata (bona fide) in the field, although their egg masses are distinctive [4].

So users of the USGS-NAS database will find these four differently-sized pies cut into seven differently-sized pieces: maculata, canaliculata, diffusa, bridesii, haustorum, cumingi, and “Pomacea species.”  Again, I really don’t trust any of the identifications upon which any of the resulting maps are based, and would advocate collapsing the categories ecologically, into “Exotics that do eat macrophytes” (maculata, canaliculata, haustorum, and probably “species”) and “Exotics that do not” (diffusa, bridgesii, and cumingi).

I have similar misgivings about almost all the pulmonate groups.  Lymnaea auricularia can be identified unambiguously, but the distinction between “Planorbella duryi” and “Helisoma species” gives me pause, and just the thought of clicking on some of those physid links scares me to death.  What the heck is exotic “Physella species?”  Some of the things in my 9-year-old son’s bedroom did not warrant close examination.

But to be clear, I am not criticizing the hard-working public servants who are doing their best to administer the USGS Nonindigenous Aquatic Species database.  They are trying to play baseball in a bluegrass jam session, bless their hearts [5].

And the most important feature of the USGS-NAS database is not the maps, but rather the ready
availability of the data upon which the maps are based.  Some of the USGS records are ancient extractions from vague literature reports, while others are rigorously documented and vouchered at major museums.  As long as we users can right-click and judge the quality of the records ourselves, I can’t see how any damage can be done.  And some benefit might certainly be had.

So what fraction of the USGS-NAS data might be useful for the FWGNA project?  And should we move to incorporate it?

At this point I should register a scruple.  The primary goal of the FWGNA project has always been to survey the distribution and abundance of the North American freshwater gastropod fauna, as objectively as possible.  Early on we identified a phenomenon I called “conservation-biased oversampling" [6] which is the (self-defeating) tendency for agencies to conduct surveys directed toward putatively-endangered species.  And I have consistently tried to avoid incorporating data which might reflect such bias in the FWGNA database, albeit with mixed success.

The USGS-NAS database very clearly demonstrates a related phenomenon, which I hereby dub “invasion-biased oversampling.”  I suppose if the USGS ran a parallel site, where biologists might upload data on the native species of freshwater gastropods they found in addition to the nonindigenous species recorded at each site, such a bias would not be a problem.  But they don’t, so it is.

With that dab of balm applied to my tender conscience, last week I spent a few hours fishing around in the USGS-NAS database [7], looking for good-quality freshwater gastropod records that might reasonably be added to the FWGNA.  I focused on the Atlantic-drainage fauna of the nine-state region from Georgia to the New York line, the region with which I am most familiar.  I disqualified the Bellamya (“Cipangopaludina”) records, the Pomacea records, and any weirdo pulmonate records for the reasons outlined above.  This left me with just the four taxa it is harder to mess up: Viviparus, Bithynia, Potamopyrgus, and Melanoides.

USGS-NAS V. georgianus
Well actually, Viviparus is a bit problematic.  The NAS database contains 235 records in total: 227 of Viviparus georgianus, 7 of Viviparus viviparus and 1 of Viviparus subpurpureus.  The distinction between (the putatively native) V. georgianus and (the European) V. viviparus simply is not clear [8], but lumping those two categories and sorting geographically, I was able to extract 10 records.  Three of those records corresponded to populations already in the FWGNA database.  Four referred to Viviparus populations in the Potomac River near Washington, of which I was already aware, but which I have been unable to confirm.  The other three records were from the 1970s, not vouchered or accompanied by sufficient data [9].

The USGS-NAS database also contains (a very similar) 247 records of Bithynia tentaculata, of which 9 fall in our study area.  All nine of these records refer to the Potomac River Bithynia population already well-documented in the FWGNA database.

Although the USGS-NAS database contains a whopping 1,210 records of the New Zealand Mud Snail, Potamopyrgus antipodarium, only one, single record falls within our nine-state study area.  That would be the population in Spring Creek, Centre County (PA) with which we are already quite familiar [10].

Similarly, the 94 records of Melanoides tuberculata in the USGS-NAS database also include but a single observation in our study area.  But it is a good one.  Record #153847 reports a 2001 collection of M. tuberculata in the small coastal town of Southport, NC.  Zooming the USGS map inward shows the collection site at Bonnetts Creek, near the entrance to the “Olde Southport Subdivision.”  And reference to the online database at the North Carolina State Museum shows a lot of 82 Melanoides tuberculata shells collected in Southport on 27Jan06 under catalog number 40541.  Super – can’t beat that.

Although I have seen secondary reports of Melanoides in North Carolina [11], this is the first well-documented, bona fide record of that species I have ever seen north of Florida, east of Texas.  So the
USGS-NAS Melanoides
USGS-NAS database can, at least occasionally, serve for the effective dissemination of “information about the presence and distribution of nonindigenous aquatic species” as it was designed to do, even to such a specialist as myself.

But let me conclude this month’s essay with another anecdote from the old mail bag.  A couple years ago I got an email from a colleague in Europe asking a simple question.  He wanted an estimate of the number of freshwater gastropod species in the US Great Lakes.  I was gratified to be able to answer promptly, and I did.  I said I didn’t know [12].   So my European correspondent wrote me back incredulous, and asked, “Do you mean to tell me that the US Government charges 13 Federal Agencies to record and monitor the latitude, longitude, date and sex of every pallid 5 mm European gastropod that sets foot onto American shores, but spends not one nickel and gives not one rip about any of its own native species whatsoever?”

Yes, I told him that was indeed the case, and suggested that we might either swap faunas, or swap governments, to solve the problem.  That former solution seems to be in the works.


[1] The actual legislative and regulatory history is much more complicated than this.  The 1990 act was amended and expanded by the 1996 “National Invasive Species Act,” and a body called the “National Invasive Species Council” was also created by Executive Order in 1999.  Exactly why the Nonindigenous Aquatic Species database landed in the US Geological Survey, as opposed to the Fish & Wildlife Service, or the USDA Department of Pests and Weeds, or the Coast Guard, or the Corps of Engineers (both of which were explicitly charged in the 1990 act) I have no idea.

[2] I do feel considerable sympathy for our long-suffering civil servants here.   It amazes me how often freshwater mollusk invasions are not single-species efforts, but rather seem to result from conspiracies of multiple species nearly indistinguishable from each other.  The zebra mussel / quagga mussel invasion is a prominent example, of course, as is the situation with the purple-Corbicula and the white-Corbicula.

[3]  Community Consequences of Bellamya Invasion [18Dec09]

[4]  Although the distribution data are vintage 2006, there are excellent illustrations of the various Pomacea species and their egg masses in a colorful PDF flyer available from the Florida Fish & Wildlife Commission:
  • Non-Native Applesnails in Florida [pdf]
[5] Science and Public Policy are not compatible, but they’re not incompatible either.  They’re two entirely different things.  See any of my essays under the menu item “Science and Public Policy” at right above for more.

[6] Toward the Scientific Ranking of Conservation Status – Part III [19Mar12]

[7] I simply blocked and copied from the “Collection Info” page(s) for each species of interest, then pasted into an excel spreadsheet.  I could have gotten a lot more data if I had requested a “custom query” from the NAS staff, but screw it.

[8] It seems possible to me that all the Viviparus populations that have spread throughout the American North and Midwest in recent decades may be a cryptic invasion of the European V. viviparus, but no actual data have been brought to bear on the question as yet.

[9] These three records from the 1970s got the sticky-note treatment.  I marked the creeks involved with sticky-notes on my Maryland map book.  Next time I’m in the area…

[10] Potamopyrgus in US Atlantic drainages [19Nov13]

[11]  Anderson, T. K. (2004) A review of the United States distribution of Melanoides tubeculatus (Muller, 1774), an exotic freshwater snail.  Ellipsaria 6: 15-18.

[12] This quote comes from Mark Twain’s (1875) Old Times on the Mississippi.  The dialogue between The Captain and the author continues:
“You—you—don’t know?"  The captain mimicked my drawling manner of speech. “What do you know?”
“I—I—nothing, for certain.”
“By the great Caesar’s ghost, you don’t know enough to pilot a cow down a lane.”

Tuesday, September 22, 2015

5:57 of Physa!

I stopped by to see our good friend Bobby Martin of Martin Microscope at the Society For Freshwater Science meeting in Milwaukee this past May. And we got to talking, and one thing led to another. And two months later, out popped a six minute video of an individual Physa acuta crawling around in circles. Enjoy!

Thursday, September 3, 2015

The Lost Thesis of Samantha Flowers

Warning.  The essay below is the fifth in a five-part series on species relationships in the enigmatic North American “stagnicoline” lymnaeids.  I will assume that you have read all four of my previous posts.  In addition, I also make explicit references to two essays in my 2012 series on this same subject, [10May12] and [4June12].  In fact, it would probably help if you started with my [20Nov06] essay on F. C. Baker, and read my [28Dec06] essay on the classification of the Lymnaeidae as well.  Stand back, I’m going to try Science! [1]

Insofar as I was able to determine from my vantage point 820.64 miles south of Ann Arbor, Samantha made good progress on her thesis research through the 2012-13 academic year, and into the field season following.  I was pleased to see the abstract of a talk she gave at the AMS meeting in The Azores in July of 2013, although I myself was unable to attend.  And on 15Aug13 I received a very upbeat email from her, my first in over a year.  She reported that she was “currently on the last leg of my Master's journey, prepping a manuscript to recount my arduous tale of stagnicoline systematics that should be wrapped up within the next month or two.”  She also promised to keep me posted “for when the sequences are thrown up on GenBank [2].”  And that was to be the last I ever heard from her.

As that “month or two” stretched into 2014, with no reply to my repeated emails, I began to worry that something might be amiss with our promising young malacologist.  Googling around on the University of Michigan website, I was able to confirm that Samantha did indeed defend her thesis, “Inferences into species delimitation of Nearctic Stagnicola using geometric morphometric and phylogenetic methods,” on November 15, 2013.  The outcome I was unable to determine.  But surely, I thought, if her thesis were successfully defended and signed, it must ultimately appear for download (or purchase?) through some public outlet somewhere, yes?

No.  After more than a year of watchful waiting, in January of 2015 I finally emailed her major advisor, Tom Duda, to inquire about the fate of Samantha and her thesis.  Tom confirmed that Samantha’s 2013 defense was indeed successful, and that he himself was surprised not to find her thesis uploaded to the University of Michigan’s “Deep Blue” server.  Apparently The University does not have firm rules regarding the deposition of MS theses.  And Tom further confessed, “In the past we have requested that theses and dissertations be deposited in our Mollusk Division library, but regret that it was my oversight (in combination with her rapid departure and her not responding to emails after she left) that got in the way of this happening with Samantha.”

And in fact, as our conversation developed, it materialized that Tom did not have a clean, final copy of Samantha’s thesis himself.  He had apparently returned his only copy to her with written comments, and she disappeared.  I suggested that he might check with some of the other members of her committee, and he was able to locate a “near final form” version which he shared with me in April.  But Tom has asked me not to distribute the document any further, since the version from which I am working still has some errors.

Samantha’s Thesis [3] is a blockbuster. Her results simultaneously reinforce a large and growing body of research confirming the dramatic ecophenotypic effects of habitat on freshwater gastropod shell morphology, and shatter 200 years of set notions about systematic relationships in the North American stagnicolines.  Let’s digest her work in five steps.

First, Samantha’s CO1 sequence data suggest two biological species.  Perhaps some of you will recall the review of interpopulation sequence divergence in L. stagnalis I posted on the FWGNA blog in [4June12].  There I argued that the general rule-of-thumb estimate of 5% CO1 divergence often observed among biological species of pulmonate snails seems applicable to within-continent comparisons of lymnaeid populations worldwide.  This is not a law, it is a very broad-brush guideline [4].

So below I’ve reproduced a (rather heavily-edited) version of Samantha’s “Collapsed Bayesian-inferred CO1 tree,” with state and province abbreviations marking samples from ME = Maine, MI = Michigan, MB = Manitoba, and so forth.  Setting aside the single Lymnaea arctica sequence that Samantha mined from the Barcode of Life Database [5], the ABGD prior max distance bars at right seem to suggest the two clusters of stagnicolines I have labelled “V1” and “V2”.  Although the pairwise sequence differences between these two groups apparently do not consistently reach 5%, an eyeball estimate from Samantha’s scale bar, together with the plot of pairwise genetic distances Samantha offered elsewhere in her thesis, suggests to me that they probably often do.

Note that I have modified the noun “species” with the adjective “biological” here.  This is because populations of the two putative species seem to occur sympatically, at least in some cases.  More under my fourth point, below.

Second, the distinction between these two putative biological species does not coincide with taxonomic tradition, as historically based on shell morphology.  Samantha classified each of the individual snails she sampled for her C01 analysis using geometric morphometrics, digitizing their shell outlines with the large set of sliding landmarks [6] shown in the colorful figure I have reproduced at the top of this essay [7].  She recognized four nomina by shell fatness – identifying the green and red categories as emarginata, the gold as elodes and the blue as exilis.  The gold was an unfortunate color choice – nearly invisible between the red and blue in her figure. 

But in any case, the correct way to define any of these nominal taxa would have been by reference to populations sampled from their type localities.  God Knows I Tried to help Samantha with this critical component of her thesis, but for a variety of reasons, it just didn’t work out.  So I have deleted Samantha’s specific names from the CO1 tree above [8] and substituted simple color coding according to her morphometric analysis [10].  And it will be obvious that the four color categories do not correspond to the two putative biological species.  Cluster V2 shows all four colors, and cluster V1 shows three of the four.

Third, the putative biological species do coincide with Brady & Turner’s V1/V2 taxonomy.  Here I’ll ask you to open my essay of [10May12] in a separate window, and refresh your memory regarding Brady & Turner’s “cryptic stagnicoline” populations from NW Pennsylvania.  Although all four of the B&T populations inhabited fishless marshes, and all four bore dark, skinny shells typical of elodes, their “Hartstown Marsh” population demonstrated a consistently larger (and perhaps more “flat-sided”) body whorl than their Conley, Osgood, and Killbuck populations.  Kip Brady’s common garden experiments suggested that this body whorl difference seemed to be heritable.

Brady & Turner [11] considered that their Conley, Osgood, and Killbuck populations demonstrated “typical” L. elodes shell morphology, and called them V1.  They called their Hartstown Marsh population V2.  See note [12] for an interesting story about the example specimens figured at right below.

I forwarded samples of all four B&T populations to Samantha in July of 2012 [13].  And sure enough, samples from the Hartstown population (marked as PA-h on my version of Samantha’s CO1 tree) appeared genetically distinct from the Conley, Osgood, and Killbuck samples (marked PA-c,o and PA-k).  So although subtle, there does appear to be a shell morphological correlate to C01 sequence divergence between the two putative species.  The key character does not seem to be the traditional fat/skinny dichotomy, but rather the relative size of the body whorl [14].

Fourth, evidence suggests that the traditional taxonomy of North American stagnicolines may have been based on shell characters largely ecophenotypic in their origin.  The best example, ironically, comes from Douglas Lake, the home of the University of Michigan Biological Field Station.  Samantha sampled 4 individuals from the waters of Douglas Lake itself, all of these being classified as “emarginata-ovate” by her morphometric criteria, which I have marked with green letters “d” in the C01 tree above.  This small sample included three individuals belonging to putative biological species V2, and a single individual belonging to putative species V1.  Samantha also sampled 8 individuals from “Douglas Lake Pools,” presumably marginal ponds not directly connected to the lake itself.  All of these individuals were classified as exilis by Samantha’s morphometrics, and are marked with blue letters “d” above.  This included 6 individuals classified as putative species V2, and 2 classified as species V1.

Thus Samantha’s data suggest that two biological species of stagnicoline lymnaeids seem to co-occur sympatrically in Douglas Lake, both bearing fat shells of emarginata morphology in the main lake, and both bearing skinny shells of exilis morphology in marginal pools.  We search the world over, and sometimes the answers we seek are right on our own doorsteps.

And fifth, we do not actually know the correct names for either of the putative biological species.  Here I must pause, and wipe a tear from my eye.  For some reason known but to God, Samantha did not sequence that sample of topotypic L. catascopium I gave her in June of 2012.  Was this tragic oversight related to some sort of funky decision-making late in her research, regarding the taxonomy to be employed in her thesis as a whole?  See note [8] below for more.

In any case, as I have repeatedly emphasized (to Samantha, and to you all as well!), catascopium (Say 1817) is the oldest name available for any North American stagnicoline population.  One of Samantha’s two putative biological species almost certainly must be catascopium by definition, and the correct name of the other species depends.

So what to do?  Almost all of Samantha’s pale/fat snails, which might conventionally be identified as catascopium, were classified as V2.  This set included the sample I sent her from Maine, graphed as a big green triangle at the top of her C01 tree.  And almost all of Samantha’s V1 individuals demonstrated the dark/skinny shell morphology conventionally associated with elodesSo let us provisionally call the V2 species Lymnaea catascopium, leaving the name Lymnaea elodes for putative species V1.  This is admittedly a judgement call, but seems most consistent with the taxonomy currently employed by workers in the field.

Have I beat this horse long enough?  Let me conclude with two recommendations for further study.  First, the hypotheses advanced here can be tested with a good genetic survey of the stagnicoline populations inhabiting the Douglas Lake area.  Somebody needs to use microsatellites, or old-fashioned allozymes, or even older-fashioned breeding studies, to test the hypothesis that two reproductively isolated stagnicoline species are sympatric in that lake, not corresponding to the traditional fat catascopium / skinny elodes dichotomy, but rather corresponding to the new V1 elodes / V2 catascopium dichotomy.  And second, somebody needs to go back up the Delaware River and fetch us some more topotypic catascopium.  And find us some topotypic elodes at Lake Canandaigua, while shopping around in Yankeeland for lymnaeids anyway.  Not it.


[1] This catch phrase comes from the online comic, xkcd.com.  And although the xkcd logo shows a stick-figure scientist flamboyantly flourishing a beaker and a calculator, real science is at least as much theoretical as applied.  To be quite precise, science is the construction of testable models about the natural world.  This essay is real science.  Stand back.

[2] Not only did Samantha ultimately fail to make her MS thesis available from any public outlet, she also failed to “throw up” any of her sequence data on GenBank.  Alas.

[3] Flowers, S. L. (2013)  Inferences into species delimitation of Nearctic Stagnicola (Gastropoda: Lymnaeidae) using geometric morphometric and phylogenetic methods.  M.Sc. Thesis, University of Michigan, Ann Arbor.

[4] Two disclaimers.  First, gene trees are NOT species trees!  They are weak, null models of population relationship.  And second, there is no cut point for species-level sequence divergence that isn’t more exception than rule.  See, for example:
  • Phylogenetic Sporting and the genus Laevapex [20July07]
  • Gene Trees and Species Trees [15July08]
  • The Snails The Dinosaurs Saw [16Mar09]
  • What is a Species Tree? [12July11]
[5] Lymnaea arctica was one of the (only approximately ten) North American lymnaeids that Hubendick (1951) considered specifically distinct.  I wish I knew more about the taxon.  Might arctica demonstrate genetic affinities with the Old World palustris/corvus/fuscus group?  But I went over to the “Barcode of Life” database to see if I could find the PPCHU85 arctica sequence that Samantha analyzed in her CO1 tree, and came up dry.  Very frustrating.

[6] Samantha really should have digitized more than the shell outlines.  In particular, the relative sizes of the shell whorls, especially the body whorl, seem to contain a great deal of heritable information in freshwater gastropod populations [14], which may be difficult to recover without landmarks on the suture lines or aperture.  See for example:
  • Dunithan A, Jacquemin SJ, Pyron M (2012) Morphology of Elimia livescens (Mollusca: Pleuroceridae) in Indiana, U.S.A. covaries with environmental variation. Am Malac Bull 30:127–133.
  • Dillon, R. T., S. J. Jacquemin & M. Pyron (2013)  Cryptic phenotypic plasticity in populations of the freshwater prosobranch snail, Pleurocera canaliculata.  Hydrobiologia 709: 117-127.  [PDF]
  • Dillon, R. T. & S. J. Jacquemin (2015)  The heritability of shell morphometrics in the freshwater pulmonate gastropod Physa.  PLoS ONE 10(4) e0121962. [PDF]
[7] Samantha’s original Figure 5 had a nasty little error in its legend, which I have fixed by deleting her legend in its entirety.

[8] Although Samantha did not explicitly cite any reference works to support her taxonomy, it is my impression that her choices of the category names emarginata-ovate, emarginata-narrow (“canadensis”), elodes and exilis follow the 1992 work of Burch & Jung [9]. Whatever the origin, her taxonomy is most unfortunate.  For unexplained (indeed unexplainable) reasons, Samantha seems to have dropped the oldest specific nomen available for stagnicoline lymnaeids, catascopium (Say 1817), from her methods and results sections in favor of emarginata (Say 1821).  But (I’m guessing here) the decision may have come late in her project?  Because a couple samples remain identified as “catascopium” in her draft Table 1, with purple coding in her draft Figures 10, 11, and 12.  What a mess.

[9] Burch, J. B. & Jung, Y. (1992) Freshwater Snails of the University of Michigan Biological Station Area.  Walkerana 6(15): 1 – 218.

[10] It is my broad-brush impression, based on nothing more than inspection of the figures in Samantha’s draft thesis, plus the sets of stagnicoline shells figured by Burch and Jung, that samples our Michigan colleagues tend to call emarginata-narrow (“canadensis”) and elodes may tend to represent putative species V1, and the samples our colleagues call emarginata-ovate or exilis may tend to represent V2,  But since Samantha didn’t digitize the shell aperture or suture lines, the distinction was not recovered by her morphometrics.  So let’s just focus on Samantha’s color coding, and set her taxonomy aside to the extent possible.

[11] Brady, J. K & A. M. Turner (2010) Species-specific effects of gastropods on leaf litter processing in pond mesocosms.  Hydrobiologia 651: 93-100.

[12] For several weeks during the spring and early summer of 2012, I held cultures of the four B&T populations here in Charleston, dissecting samples to hunt for anatomical distinctions that I ultimately did not find. During that period both the Killbuck (V1) and Hartstown (V2) populations laid eggs.  These I hatched and reared for quite a few months in my standard plastic aquarium boxes, at densities that were certainly too high, largely neglecting them, changing their water infrequently.

In any case, my results seem to confirm those of Kip Brady.  My standard culture water here in Charleston is almost certainly much softer than that to which stagnicoline lymnaeids are usually adapted, yielding the chalky appearances of the two example shells figure above.  Yet the V1 offspring did indeed seem to develop relatively smaller body whorls than the V2 offspring.

[13] And here’s another little confusion.  Unknown to me, Kip Brady sent Jack Burch samples from a couple of his stagnicoline populations several years prior to my shipment to Samantha.  Kip never heard anything further.  But apparently 5 of Kip’s earlier samples were sequenced at some point along with 8 of the individuals I sent to Samantha in 2012, and all 13 appear graphed side-by-side in Samantha’s C01 tree, under two different labelling schemes.

[14] Body whorl differences of this subtle sort seem to be quite heritable in freshwater pulmonates as a general rule.  In fact, body whorl differences were the way we initially distinguished Physa carolinae from Physa acuta back in 2009 [15].  For more, see:
  • The Lymnaeidae 2012: A clue  [9July12]
  • The heritability of shell morphology in Physa h^2 = 0.819  [15Apr15]
[15] Wethington, A.R., J. Wise, and R. T. Dillon (2009) Genetic and morphological characterization of the Physidae of South Carolina (Pulmonata: Basommatophora), with description of a new species.  The Nautilus 123: 282-292.  [PDF]

Wednesday, August 19, 2015

The Type Locality of Lymnaea elodes

Editor’s Note.  This is the fourth installment of what I think will turn out to be a five-part series on the tangled species relationships of the North American stagnicolines.  It’s not essential, but you might find it helpful to read my essays of [22June15], [14July15], and [29July15] before proceeding onward.

Last month I noted that Thomas Say described two “stagnicoline” lymnaeids in 1821, the (pale, fat) Lymnaeus emarginatus from “lakes of Maine” and the (dark, skinny) Lymnaeus elodes [1].  Say was much more precise about the type locality of the latter species, specifying that it “Inhabits Canandaigua Lake.”  And apparently he considered his Lymnaeus elodes so distinct that he did not feel called to distinguish it from any other North American freshwater gastropod [2].  The figure below was scanned from Say’s 1830 “American Conchology” [3].

From my (perhaps selfish?) perspective almost two centuries later, vague type localities such as that for emarginata seem preferable to specific ones, such as that for elodes.  So much has changed here in the United States, over the last 194 years, that references to specific type localities may well have been rendered obscure, or the environment radically altered, and its biota extinct.  But vague type localities would seem to afford a modern researcher, such as myself, some wiggle room.
So as the vagaries of my 2012 field season played out, late July was scheduled for an extensive survey of northern Pennsylvania, home ported at the University of Pittsburgh’s Pymatuning Laboratory of Ecology [4].  And I calculated that at least one of my excursions out of PLE might take me within striking distance of the elodes type locality on Lake Canandaigua.

And once again I had done some homework – this time, a bit more thoroughly.  Digging around in the older literature I was pleased to unearth a charming paper written in 1932 by my hero [5] F. C. Baker: “The Ecology of Say’s Limnaeus elodes [6].”  Regarding the type locality, Baker wrote: 
“It is obvious that a pond or swamp-inhabiting snail would not live in the waters of a large lake like Canandaigua and its exact ecological station must necessarily be sought in a normal habitat near the lake.  No specimen of elodes has ever been found living in the lake.  Many years ago the north end of the lake, where the outlet discharges its surplus waters, was an extensive swamp or marsh inhabited by elodes and other mollusks.  This area has now been drained for building purposes.  The southern end of the lake is also marshy.  It is probable that the specimens from which Say drew up his original description came from the north end of the lake, either in the marshy tract bordering the outlet, or from a beach pool or pond bordering the upper (southern) end of the lake.”
So I arrived at the upper end of the Canandaigua Lake in the late morning of 27July12, launched my kayak from the Woodville Access, and paddled south to prospect for a possible “beach pool or pond bordering.”  My goodness, it was swampy in there, with luxuriant growths of floating and emergent macrophytic vegetation.  I can rarely remember seeing larger populations of Physa acuta or Lymnaea columella.  I also netted a few Gyraulus deflectus and Valvata tricarinata, both of which were interesting to my southern eyes.  But I was looking for elodes habitat, which should be isolated and essentially fishless.  And to quote my own field notes of 7/27/12 verbatim, “If there are any vernal ponds isolated in this vast sea of cat-tails and swamp forest, one could not find them from a kayak.  The only way to find stagnicoline habitat here would be by helicopter.”

So I paddled back to the truck and drove along the western shore of the lake, a distance of perhaps 15 miles, noting (as Baker’s paper had led me to expect) a “very precipitous” shoreline featuring essentially zero habitat for freshwater gastropod populations of any sort. 

And when I arrived at the lower (northern) end of the lake, I again found it as Baker described in 1932, “drained for building purposes.”  More so today, I feel sure.  I did enjoy a lovely stroll in what probably represents the vestigial remains of Baker’s “extensive swamp or marsh inhabited by elodes,” now maintained (rather nicely) by the City of Canandaigua as “Lagoon Park.”  And I was impressed by the aquatic vegetation in the shallow ponds protected within the park, as well as by their large populations of bream, bluegill, and panfish of all sorts.  Pleasant to the eye of the visitor, certainly, but most inhospitable for Lymnaea elodes
Fortunately I had an ace up my sleeve.  The occasion of F. C. Baker’s 1932 paper was not to lament the absence of L. elodes from the southern, western, and northern shores of Canandiagua Lake, but to rejoice in their abundance on the eastern.  He wrote:
“A few years ago, while exploring the east side of the lake, a large beach pond was discovered in which were living many large pond snails of the form known as elodes.  These shells are exactly like Say’s types deposited in the museum of the Philadelphia Academy and like his figures in the American Conchology… The pond (Fig 1) is situated about three miles south of the City of Canandaigua… near a group of summer cottages erected on higher ground southward.”
Baker’s Figure 1 is reproduced above.  What a lovely spot, even in black and white!  Baker described the open pool as covering about three acres, with perhaps two additional acres of “surrounding vegetation” (which he cataloged in detail), ten “species and races” of freshwater gastropods, and three species of pisidiid clams.

So leaving The City of Canandaigua and driving approximately three miles south on the eastern shore of the lake, I encountered, in this order: a “Deep Run Park,” a “Crystal Beach,” and a “Cottage City.”  Deep Run Park was a nice public beach administered by Ontario County (NY), with picnic facilities and plenty of free parking, but no habitat for stagnicoline lymnaeids in evidence.  Cottage City turned out to be a modest community of (primarily) vacation homes dating back to the Victorian era, perched (as Baker indicated) “on higher ground southward.”  And what about that “Crystal Beach” in the middle?

Google Earth does indeed suggest a wooded depression (or vernal pond?) in the region of my map marked “Crystal Beach.”  But alas, I could find no public access.  Here is a photo I downloaded from the Facebook page of the Crystal Beach Betterment Association:

I didn’t see any images depicting marshy or swampy areas on the CBBA page, but comparing the location of their private property to Baker’s (1932) description, it seems likely to me that his pond is (or was) in there somewhere [7].

It also seems likely that with a properly-directed telephone call or two and sufficient lead time, an interested scientist such as myself might wrangle an invitation from the CBBA to explore their property for that elusive topotypic population of L. elodes.  But staring at “No Trespassing” signs as the sun set on Friday evening, 27July12, this particular interested scientist was clean out of luck.

I filed my sad report with Samantha upon return to the Pymatuning Lab that next afternoon.  She did not respond, but perhaps no response was called for.  And in fact, over a year would pass before I heard from Samantha again.  I felt sure that she was very busy up there in Ann Arbor somewhere, cranking out a forest of gene trees, or whatever it is that the young kids do these days.  Coming next time, “The Secret Thesis of Samantha Flowers.”  Stay tuned!


[1]  Say, T. (1821)  Descriptions of Univalve Shells of the United States.  Journal of the Academy of Natural Sciences 2: 149 – 179.

[2] But it is interesting to note that Thomas Say did realize that his North American elodes was quite similar to European L. palustris, from which he could not, apparently, distinguish it.  At the bottom of his description of L. elodes, Say noted: “This species was found by Mr. A. Jessup; it bears the most striking resemblance to L. palustris.  The variety was found by the same enterprising mineralogist at Morristown, New-Jersey.  I have subsequently received specimens from Mr. S. B. Collins, of New-York, who procured them in a marsh near the Saratoga springs.”  So if (as I fear) the Canandaigua elodes population has subsequently gone extinct, I think a case could be made for either Morristown or Saratoga Springs as a “substitute” type locality.

[3] Say, T. (1830 – 1838ish) American Conchology; or, Descriptions of the Shells of North America.  New Harmony, Indiana, “Printed at the School Press.”

[4] A public acknowledgement of gratitude is here extended to my good friends at The Pymatuning Laboratory of Ecology – Andy Turner, Aaron Stoler, Rick Relyea (who has since moved on) and Chris Davis (currently in charge).

[5] For more on the life and career of this remarkable scientist, see:
  • The Legacy of Frank Collins Baker [20Nov06]
[6] Baker, F. C. (1932)  The ecology of Say’s Limnaeus elodes.  Ecology 13: 286-289.

[7] For the record, here are the coordinates for my best guess on the location of Baker’s pond: 42.8147, -77.2613.  The only other nominee I can find is a shallow pond currently between Deep Run Park and a housing development, 42.8200, -77.2586.

Wednesday, July 29, 2015

The Type Locality of Lymnaea emarginata

Editor’s Note.  This is the third installment of what I think will turn out to be a five-part series on the tangled species relationships of the American stagnicolines.  It’s not critical, but you might find it helpful to back up and read my essays of [22June15] and [14July15] before proceeding onward.

The next two North American stagnicoline lymnaeids to be called to the attention of science, after Lymnaeus catascopium, were L. emarginatus and L. elodes, both described by Thomas Say in 1821 [1, 2].  The figure below, clipped from Say’s “American Conchology”[3], compares the shell morphology of emarginatus (top row) to catascopium (bottom row).  Say wrote that emarginatus “is a somewhat larger, and considerably more ventricose species than L. catascopium, S., and the undulation of the columella is much more profound.”  Say gave the type locality of his emarginatus as “inhabits Lakes of Maine.”

So by great good fortune, in the spring of 2012 my wife won a pair of tickets on Southwest Airlines in a school raffle.  And she began to cast about for potential vacation spots during the first week of July, preferably someplace cool.  And she discovered that Southwest Airlines (if you can believe this) has service to Portland, Maine, from whence (she schemed) we might rent a car to Bar Harbor.  And just as simply as that, her husband had another field trip planned.  This one of a substantially different character than the expedition he detailed in his post of two weeks ago.

So we left our lovely B&B in Bar Harbor on the morning of 5July12, and by early afternoon I was collecting Lymnaea emarginata from Pushaw Lake, about 6-8 miles north of Bangor.  The snails were quite common on rocks in about two feet of water on the west shore of the lake.  It is well that freshwater malacology is not ordinarily so easy, lest everybody should do it.

I had actually done a bit of homework before setting off on this little errand, and so my choice of Pushaw Lake was not entirely arbitrary.  Our good friend Scott Martin reported emarginata populations from four counties in his (quite helpful) 1999 review, “Freshwater Snails (Mollusca: Gastropoda) of Maine [4].”  So I contacted Scott for his specific records, and among the many potential collection sites he forwarded to me was Pushaw Lake, from which Leroy Norton reported “Stagnicola oronoensis” in 1957.  Oronoensis is clearly a synonym of emarginata.

In retrospect, however, I wish I had done more homework than I did.  A closer reading of Scott’s 1999 review would have called my attention to a 1921 paper by O. O. Nylander [5] designating Mud Lake (in remote Aroostook County, 150 miles north of Bangor) as the type locality for Say’s Lymnaeus emarginatus, not Pushaw Lake.  Well, as the whole project turned out, it didn’t matter.

Rob at Pushaw Lake
And my efforts to collect a corresponding population of Lymnaea elodes were much more in keeping with my many years of personal experience in the matter of the pulmonate gastropod sampling.  Scott Martin actually listed six Maine counties for dark/skinny elodes-type stagnicoline populations, but his records were far more vague.  His best locality data were for a “Lymnaea palustris” population at the “Andrascoggin River above Rumford.”  And indeed, I found extensive, seasonal swamps along the right bank of the river in that area, absolutely primo habitat for mosquitos on July 5, but no sign of L. elodes.  The ANSP also holds a couple collections from the vicinity of Portland (Stroudwater and Westbrook) where I did no better.

Well, as the whole project turned out, it didn’t matter.  Oops, am I repeating myself in my old age?  This is a chord I have found myself striking with increasing frequency, as my perspective has matured, these latter years of my career.  What we do ain’t brain surgery, I often tell my students.  It’s just snails.

So I contacted Ms. Samantha Flowers [6] immediately upon my return to Charleston, and she was predictably pleased to hear about the bona fide emarginata population I had collected for her from a “Lake of Maine.”  She suggested that if I could ship the Pushaw emarginata to her alive at the University of Michigan Biological Field Station way up by Douglas Lake, she would be interested in attempting some breeding studies with dark/skinny populations of elodes and exilis from the Michigan area.  Which (of course) I was happy to do, out of my own pocket.

And with my July (2012) shipment to Samantha, I also included ethanol-preserved samples of four dark/skinny stagnicoline populations from NW Pennsylvania, which had been sent to me earlier that same the summer by Kip Brady and Andy Turner.  These were the “cryptic stagnicolines” I first mentioned in my essay of 10May12, and mentioned again last month.  Very mysterious, those populations…

…keep your eye on them!  And tune in next month, as we continue our quest to elucidate the tangled systematics of the enigmatic North American stagnicolines with “The type locality of Lymnaea elodes.”


[1]  Say, T. (1821)  Descriptions of Univalve Shells of the United States.  Journal of the Academy of Natural Sciences 2: 149 – 179.

[2] To be complete, it might be argued that Thomas Say described as many as five stagnicolines in the work cited above, including elongatus, reflexus, and desidiosus as well as emarginata and elodes.  Say realized that his nomen elongatus was preoccupied, and changed it to umbrosus himself in his "American Conchology" [3].  The identity of desidiosus as a stagnicoline (as opposed to a fossarine) is controversial – see the remarks of Baker (1911, pp 318 – 321).  I’m not sure what happened to reflexa.  The nomen was passed along by Baker (1911, 1928) as perfectly valid for dark, marsh-dwelling stagnicoline populations of very skinny shell morphology, but appears only as a “form” of elodes in Burch (1989).  I don’t know how it got so demoted.

[3] Say, T. (1830 – 1838ish) American Conchology; or, Descriptions of the Shells of North America.  New Harmony, Indiana, “Printed at the School Press.”

[4] Martin, S. M. (1999)  Freshwater Snails (Mollusca: Gastropoda) of Maine.  Northeastern Naturalist 6: 39 – 88.

[5] Nylander, O. O. (1921)  The type localities of Lymnaea emarginata Say and L. ampla Mighels.  Nautilus 34: 77-80.

[6] From this point to the conclusion of the essay, I am assuming that you are familiar with last month’s post,
  • Everything Changed When I Met Samantha [22June15]