The Mystery of the Michigan Duskies

This April I had the honor of finding a Northern Dusky Salamander in the state of Michigan, at a spot in the thumb. The spot had muddy natural seeps, flowing streams, and a hemlock ground cover reminiscent of the Catskills. This spot also has Southern Two-Lined Salamanders, the only spot in MI for both. The area is very hilly and moist, but it remains a mystery as I reflect on my herping season, exactly how this population would end up 300+ miles from the nearest other population. I am thinking that maybe someone set them there, although this is unlikely due to low interest in our collective hobby. If anyone has any ideas, don't hesitate.

Strange. I've never found/heard of anyone finding species that aren't listed for our state. Unless you count the marbled salamander I found right by the border of Ohio and Michigan. Did you take any pictures?

There have been a couple people studying these disjunct populations. I saw a nice talk on the topic a couple of years ago. Let me see if I can dig up who the speaker was.

I also lean toward them being released populations (along with 6-line racerunners, whose next closest population is in Illinois!). But that's a hard sell. For one, you've got to release enough animals that they create a viable population, and for two, you have to release them in an area where they'll thrive.

Of course, neither duskies or 2-lined are all that picky about their habitat, but they do like it wet and seepy, which isn't especially common in Michigan.

I did get a few pictures of the D. fuscus. I found it under a rotting log in a muddy natural seep leading into a swift stream. I do not have the SD card I used handy right now, butI will post the pics on here by Friday. In the pictures, you can clearly make out an eye-jaw line, and the profile of a dusky, there's no mistaking it.

Here are a few Desmognathus fuscus that I photographed at that site:




And a Eurycea cirrigera, too.


The origin of the population is being/has been assessed, but I don't know the results.

There are a number of interesting disjunctions and recent range extensions in the northern midwest. Despite recent development and a perception that these are thoroughly explored areas, I think that the reality is that much of this region was "frontier" only a century ago, and has actually only been poorly explored herpetologically. If natural, and for the moment I assume this is so, 300 miles is not a huge range extension for either of these species. I think it's rather telling that one of the species mentioned is Eurycea cirrigera and not E.bislineata. The latter would be a smaller range extension, but across terrain which seems on average less suitable. The former however, already has a known disjunction to the west and the body of its range to the south. This suggests to me that the species expanded its range northward following glaciation, but has had its northern range fragmented by warming and drying or by modern development. If this is so, then one could expect either or both of these species to exist in other locations in southern Michigan and northern Indiana, especially along the ridge of highlands that runs NE-SW through the region. That ridgeline likely provides pockets of suitable habitat for both species. It's also possible that Desmognathus could have expanded its range via pockets of habitat around the edges of what is now Lake Erie [as in its only known Ontario occurences, in the Niagara Gorge].

Both species have been reported from Michigan recently. It would be important to know if your locality is a different one from those so far reported. E.bislineata has also been documented in Michigan.

ADW: Desmognathus fuscus: INFORMATION
Eurycea cirrigera: Southern Two-Lined Salamander | Flickr - Photo Sharing!
List of amphibians of Michigan - Wikipedia, the free encyclopedia
Field Herp Forum • View topic - Meechigan Spring

It might be prudent to watch for Gyrinophilus and Plethodon glutinosus, as the ranges and potential extensions are comparable.

I did not know that the "southern" two-lined salamander had been found that far north! That is intriguing. Both Petranka's and Lannoo's books mention that the systematics still need a thorough work over, and that populations in contact zones between E. bislineata and E. cirrigera can hybridize.

What are the most reliable traits used to distinguish between these species, assuming that you're not dealing with hybrids? Petranka mentions the length to which the dorsolateral stripes go along the tail, and that E. cirrigera have stripes that "extend to near the tip of the tail." The critter in the photo above has stripes that appear to break up at the base of the tail. But I wonder how reliable a character this is, as I've seen a lot of variation in pops. of E. cirrigera in terms of other aspects of their color and pattern as transformed individuals (i.e., many to few dark spots dorsally, dark-caramel to bright yellow background colors) and especially as larvae.

Also, those are really gorgeous photos! Well done!

In my very limited experience, all three species have been easy to differentiate at a glance, but the species complex appears to include several additional species, including more than one paedogenetic type (such as E.aquatica), and two morphologically distinct species treated as E.wilderae. The species accounts in Amphibian Declines, however, indicate that the standard morphological traits are unreliable in this complex. I doubt there is much, if any, current evidence of extensive hybridization - it's more likely that these perceptions were based largely on unfamiliar species boundaries and unrecognized but distinct species. E.junaluska is also part of this complex, and has been considered at times to be an intergrade of E.cirrigera and E.bislineata.

Petranka's book is a vital reference, but it is extremely conservative taxonomically. There are a number of more general guides which are both more recent and more up to date on distribution and taxonomy. I don't yet know of any titles which include any of these three range extensions [add E.longicauda to my list of possibles, as it too has a similar known range]. The defined ranges seem to have changed appreciably since the elevation of E.wilderae and E.cirrigera to full species, presumably because such elevation was based on more extensive knowledge of geographic variation in genes and morphology in the complex.

I presume that the reference to "Lannoo" is actually to the following accounts in "Amphibian Declines", none of which indicate significant hybridization:
Kozak,K.H., & M.J. Lannoo, 2005. Eurycea aquatica Rose and Bush, 1963. Dark-sided salamander.
Sever, D.M., 2005. Eurycea bislineata (Green, 1818). Northern two-lined salamander.
Pauley, T.K., & M.B. Watson, 2005. Eurycea cirrigera (Green, 1830). Southern two-lined salamander.
Sever, D.M., 2005. Eurycea wilderae Dunn 1920. Blue Ridge two-lined salamander.
Sever's accounts above can be downloaded from his website:
http://www2.southeastern.edu/Academics/Faculty/dsever/brief.html

I would perceive E.cirrigera as being as much a "western" species, as a "southern" one.

The following are probably still the best general accounts of the three species. I will have to re-examine my photos, as I suspect that my E.cirrigera might actually be southern "wilderae".
http://www2.southeastern.edu/Academics/Faculty/dsever/BislineataCat1999.pdf
http://www2.southeastern.edu/Academics/Faculty/dsever/CirrigeraCat1999.pdf
http://www2.southeastern.edu/Academics/Faculty/dsever/WilderaeCat1999.pdf

If you look at the map of E.cirrigera, you should see that the northwestern limit abuts a parallel ridgeline [visible as the area between mapped rivers] which separates the NE Illinois population, and which extends well up into SE Michigan. This is the area which I suspect harbors additional populations.

This is also an interesting source, though I'm not sure I have the full paper. Even from the first page, you should be able to see the history of confusion. Both Sever's description of the accepted ranges, and his indication of inconsistant data in Ohio, hint at the later reassignment of many of those populations from E.bislineata to E.cirrigera.
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[I presume that the reference to "Lannoo" is actually to the following accounts in "Amphibian Declines", none of which indicate significant hybridization[/QUOTE]

You are correct, I am referring to Amphibian Declines, and what I was referring to was the mention of the potential for hybridization: "Northern two-lined salamanders and southern two-lined salamanders will hybridize (Noble and Brady, 1930), and broad regions of intergradation exist between these forms of two-lined salamanders (Howell and Switzer, 1953; Mittleman, 1966)."

Thanks for the links to Sever's work. I'm going to try to get my hands on a few of those catalogues.

If anyone is interested, a number of the species accounts in the Catalogue of American Amphibians and Reptiles are available free to download from ZenScientist.

Lamb said:

I presume that the reference to "Lannoo" is actually to the following accounts in "Amphibian Declines", none of which indicate significant hybridization

Click to expand...

You are correct, I am referring to Amphibian Declines, and what I was referring to was the mention of the potential for hybridization: "Northern two-lined salamanders and southern two-lined salamanders will hybridize (Noble and Brady, 1930), and broad regions of intergradation exist between these forms of two-lined salamanders (Howell and Switzer, 1953; Mittleman, 1966)."

Thanks for the links to Sever's work. I'm going to try to get my hands on a few of those catalogues.

Click to expand...

Note that the sources of that information are effectively archaic, and pre-date [for the most part] the descriptions of E.junaluska, E.bislineata major, E.bislineata rivicola, revisions which placed E.b.rivicola first in E.bislineata bislineata and later in E.cirrigera; revisions which elevated E.wilderae and E.cirrigera, and studies which recognized E.wilderae as probably two species and E.aquatica as probably two valid species. In essence, old views of hybrid zones have largely been replaced with a view that several distinct species are involved instead. Overlap in characteristics isn't due to interbreeding, but due to more diversity than originally understood.

The CAAR accounts written [in part] by Sever can be obtained directly from him via the links provided. Obviously, accounts not by him must be obtained elsewhere.

FrogEyes said:

In essence, old views of hybrid zones have largely been replaced with a view that several distinct species are involved instead. Overlap in characteristics isn't due to interbreeding, but due to more diversity than originally understood.

Click to expand...

It will be interesting to see how these populations and species play out in the future.

These are the pictures of the Northern Dusky I found in a muddy seep off one of the roads. The spot was very moist, and the first piece of wood in the muck yielded this guy. Couldn't find that Two-liner though.

Judging by the titles of your photos, that's a known location for duskies and for northern two-lined. That raises the question of which ID is correct, or whether both two-lined are present in the area.

I know this is late... but I found a population of pygmy salamanders in scott county va not to far from the va border and it wasn't a known location for them. They are in TN and VA but where I found them is pretty far from most places they occur in either state. this was a low elevation road side stream but was very clean clear and cold.

I'm telling you, crazy things happen in the herping world every now and again. We don't understand these creatures nearly as well as we think we do, and I wonder all the time about the possibility of duskies and two-lined sallies elsewhere in Michigan. To give you another example, in the 1940s and 1950s, there were some Hellbender records from the state of Iowa in the Mississippi River drainage! I hope nature keeps surprising us. On an unrelated note, does anyone have any experience with Northern Ravine Sallies hanging out around natural springs and seeps? I have wondered about the oddity of that find for two years now.

I've found southern ravine sals beside a creek in the surrounding "sloping" forest. I'm sure they dont get in creeks or springs but they are sometimes near them.