A few weeks ago Dr. Catherine Newman, a biologist at Louisiana State University, published a paper describing a new frog species, previously unknown to science. Many of us have grown accustomed to reading news about new frogs being discovered in remote, primeval forests around the world – frogs just aren’t a very well studied group, so we still have a lot to learn. But this discovery was different. The new frogs described described by Newman live in one of the most urbanized places in the world – New York City. The idea that an unknown frog was living virtually in the shadows of New York’s skyscrapers made this story an instant classic, and news outlets around the world announced the finding to great fanfare.
The remarkable thing about these frogs, however, wasn’t that they were unknown to science. It was that we knew the frogs were there all along, but no one had ever studied them carefully enough to realize they were something new! The frogs in question were clearly “leopard frogs” – a widespread group in North America – but for decades, herpetologists couldn’t agree whether they were Northern Leopard Frogs (Rana pipiens) or Southern Leopard Frogs (Rana sphenocephala). These two species look nearly identical, and the New York frogs produced calls that didn’t sound like either species. Newman and her colleagues compared DNA sequences of the New York frogs with both of the better-known leopard frog species and found strong evidence that the New York frogs belonged to a third, previously unrecognized species!
Biologists might call these New York frogs (which still don’t have an official Latin or English name) a cryptic species – a species that is genetically distinct from its relatives, but otherwise difficult to tell apart.
A thin crust of snow is slow to melt on a north-facing talus slope in the San Gabriel mountains
But if it’s not obvious that two species are different, should we really care that they are? Well, if their DNA shows that they haven’t been exchanging genes with their closest relatives for a few million years, then clearly they know that they aren’t the same species! More pragmatically, conservation biologists care about cryptic species because their genomes may contain genetic information that’s not contained in the genomes of any other species. That genetic information could be the key to a species adapting and surviving in a fast-changing world.
Coincidentally, I recently learned that Los Angeles has its own enigmatic amphibian. But unlike the familiar-but-incognito leopard frogs described in New York, ours lived completely undetected until just a few years ago.
The San Gabriel Slender Salamander (Batrachoseps gabrieli) has only been observed at a handful of sites in the San Gabriel Mountains, northeast of LA. The first specimens weren’t collected until 1985, and even then, it took until 1996 for Dr. David Wake to examine the museum specimens carefully and realize that this species was quite distinct from any of its known relatives – not just genetically distinct, but visibly different from any other species in its genus. Genetic evidence suggested that this species had split from its nearest relatives something like 10 million years ago!
As soon as I read about the San Gabriel Slender Salamander, I wanted to find it for myself! How could something so different be living right under our noses in one of the world’s great metropolitan areas? I looked up the latitude and longitude of the sites where these salamanders were first collected, and on a crisp day in early March, I drove into the mountains with my camera.
According to the scanty literature I could find, the San Gabriel Slender Salamander favored north-facing talus slopes. It was only a short hike from the highway to reach the first GPS coordinates I was looking for, and when I stopped I was faced with a long, steep expanse of loose rock – the habitat fit the bill perfectly. So I began to climb, carefully searching under rocks and logs as I went. In the first hour, I found a lot of nothing… a few centipedes and beetles scurried away when I lifted their shelters, but there was no sign that I was in salamander country.
An Ensatina eschscholtzii poses for the camera before being returned to its home under a rock.
After about an hour, I spotted what looked like a fat earthworm under a large rock… It turned out to be the tail of a retreating Ensatina eschscholtzii – a big, rubbery, dull-pink salamander that’s found in mountainous areas all over California. I was re-invigorated – there were salamanders here!
I photographed the Ensatina, returned it to its home, and continued searching for my real target. Finally, after another hour or two of methodical searching, I lifted a big, flat rock in a well-shaded section of the talus slope and saw a tiny, curved shape among the roots and pebbles – the San Gabriel Slender Salamander! It was smaller than its name, mostly black, but with beautiful golden speckles down its back.
Batrachoseps gabrieli in all of its glory!
I kept the little salamander cool and moist during a brief photo shoot (like other members of the family Plethodontidae, the slender salamanders have no lungs – they need to stay moist so they can absorb oxygen through their skin!), and then carefully returned it to its home, which I had marked with a tripod of sticks to help me find it again among the scores of similarly sized rocks that dotted the talus slope. I was so thrilled to find this amphibian enigma that I was tempted to keep looking for more, but I had satisfied my curiosity, and I decided to leave the salamanders alone.
As I gathered my camera gear to head back home, I reflected on my find. I was, at most, a ten-minute walk from a well-traveled highway. That morning, I had eaten breakfast in my apartment in LA, and I would be back home by early afternoon. While I was searching for the salamanders, the growls and rumbles of motorcycles climbing the steep, winding highway were a constant reminder that I was still very much in civilization. Yet I had just found a beautiful little animal that, when I was born in 1983, no one even knew existed.
Batrachoseps gabrieli, the little-known salamander endemic to Los Angeles County, one of the world's most heavily populated areas.
On the one hand: how could a species remain undetected for so long in a place that’s so accessible to people? On the other hand: how could it not remain undetected? With a penchant for cool, wet spaces between rocks, north-facing talus slopes were the place to be. It’s hard to imagine a slow-moving, inch-long salamander traversing ridges to get from one talus slope to another. But these salamanders have 10 million years of history behind them; that’s a lot of time to get around. And one way or another, they’ve managed to populate several talus slopes in the San Gabriel Mountains.
If there are new species of vertebrates waiting to be discovered in our own backyard, then surely there are countless cryptic species of insects and spiders all around us – and that’s just the start! Imagine the unexplored diversity among those organisms so small that we can’t even see them: rotifers, nematodes, protists, bacteria, viruses! Consider the diversity of parasites that live inside the bodies of better-known organisms. We clearly still have a lot to learn, even about the nature that’s closest to us!
Cited:
Newman, C. E., J. A. Feinberg, L. J. Risser, J. Burger, H. B. Shaffer. 2012. Molecular Phylogenetics and Evolution 63(2):445-455.
Note: The salamander images in this post were photographed using the “field studio” approach. I’ve just started working on this project with some incredibly talented photographers from around the world. What a great visual way to get people connected with the wildlife all around them!