These are compiled reports from our 2017 expedition to Mexico, which I blogged live on my personal blog. Some of the links take you to the posts on that blog, but the same content is here.
Expedition to Oaxaca and Chiapas
It’s been too long since I’ve been on a major field expedition, more than 3 years. Today I fly to Mexico to begin three weeks in the mountains of Oaxaca and Chiapas with salticidologists (jumping spider experts!) Uriel Garcilazo and Łukasz Trębicki and others interested in arthropods: Ricardo Paredes, José Arturo Casasola, Jorge León, and Gerardo Contreras. Uriel, Łukasz and I will be looking for new species of jumping spiders, with special focus on the genus Mexigonus. There are only a few species of Mexigonus described, but we already know that many more undescribed ones are hiding in the mountains of Mexico.
There are many poorly studied groups of spiders, so why did we choose to focus on Mexigonus? One reason is that it is an evolutionary radiation of the Mexican highlands, its species having diversified among the mountain ranges that fragment the landscape into isolated patches of habitat. Studying the diversity of Mexigonus species and their evolutionary relationships could help us understand the biological history of this region. Another attraction of Mexigonus is the red or orange courtship ornamentation that males of some species have — attractive to the females perhaps, but to us attractive because red ornamentation is not common in salticid spiders. There’s a good chance that most salticids can’t distinguish red (colour blind, in a sense), and so when we find a salticid that can, it could tell us something about the evolution of colour vision.
A species of Mexigonus new to science, from Oaxaca.
Our expedition has been supported generously by Tila Pérez, Griselda Monteil, and Ricardo Paredes of the Universidad Nacional Autónoma de México (UNAM) in Mexico City. We’ll drive first to Oaxaca, where we’ll spend about 10 days collecting, based at Universidad de la Sierra Juárez (UNSIJ) with José Arturo. After that we’ll spend about 10 days in Chiapas, where Jorge León (EcoSur) has been guiding our plans. At the end of the trip we’ll attend the meetings of the American Arachnological Society in Juriquilla being organized by Fernando Alvarez.
¡Adelante!
On the road to Oaxaca
Here in Ixtlán de Juárez we took the day off from collecting to catch up with our processing of specimens. We collect the spiders live. When we return from the field, we sort them to species, choose ones to photograph, and preserve the rest, freeing up their vials for the next day. The photographs take a while, and when you add it to the basic note-taking and other duties (we hope to do videos!), we usually don’t quite get done the day’s tasks. Today I had a big pile of spiders that took most of the day to photograph.
So, a belated #Mexigonus2017 report on our trip down from Mexico City. The drive was smooth on the big toll highways, and of course we chose to make a few stops to look quickly for spiders. The highlight of the day for me was to find Habronattus nahuatlanus (at least, that’s what I think it is) at Santa María Tinú and to learn its habitat — in or under grass clumps, just like the recently described H. luminosus from Arizona. Here is the male, and female. The female wasn’t known before, so it’s good to see what it looks like.
Habronattus nahuatlanus, male (top row) and female (bottom row)
We’ve had many successes in subsequent days, and I’ll report on purple tomatoes, green ghosts, and blue-legged magic as soon as I can, perhaps not in chronological order.
By the way, for English speakers who don’t know Spanish, “Oaxaca” is pronounced (more or less) as the English “Wahaca”.
Preconceptions dashed by sad faces, black pepper, and purple tomatoes
For our first full day of collecting, Arturo Casasola guided us south of Ixtlán, to the community of Lachatao. The winding mountain road brought us to a pine-oak forest that looks a lot like Canada — until you see the bromeliads decorating the trees. It wasn’t quite wet enough to be a cloud forest, but it had some of the elements — not only the bromeliads, but also many other epiphytes (plants growing on other plants) on the branches of the oaks, especially lichens and mosses.
I brought to this collecting expedition a particular concept of where Mexigonus jumping spiders live: mostly on the litter of dry fallen leaves beneath trees. I had formed this idea from previous collecting of other jumping spiders. As I’d collect Habronattus, one of my favourite groups, on such leaf litter, I’d often find a few Mexigonus along the way.
Given this preconception, when we got to the Lachatao forest, I started looking on the leaf litter, and promptly found a little humble brown and tan Mexigonus species quite common there. Good! I decided to try something bold, to look on leaf litter not on the ground, but accumulated in the crooks of branches of the trees. I found a strange cryptically-coloured Mexigonus and was motivated to keep looking above ground. In the end, the team found this cryptic Mexigonus to be common on the epiphyte-covered branches of the oaks — not the habitat of my preconceptions.
We call this species “triste” (sad) for the melancholy expression on their little faces. Here is a male.
Mexigonus “triste”, male.
It turned out that that wasn’t the only Mexigonus living above ground in the forest. We found a small peppery black species by beating dead branches of trees in shadow. (Beating is a technique we use a lot — we hold a kite-like sheet under a bush or tree and shake or hit it with a stick. For more details see here: https://www.youtube.com/watch?v=oZ1P_3fHtPk)
In the end we found two species of Mexigonus on the ground, as I’d expected, but three species beating bushes and trees (sad face, black pepper, and a third that I’ll describe next post: purple tomato). All 5 of the species are most likely new to science. This is a happy way to dash one’s preconceptions.
Purple tomato
In my last post I described our success in finding 5 new species of Mexigonus jumping spiders in the oak-pine forest above Lachatao, but I left unexplained one of the species: purple tomato.
That great prize of the day was found by Uriel. Beating some small bushes and branches of fallen pine trees, he found some female Mexigonus that looked really interesting. We decided that it was worth trying to set the whole team looking for a male. The news soon spread: Uriel found a male, and he had figured out the species’ habitat: on exposed or dead branches of bushes or fallen trees, less than a metre from the ground, with just the right amount of sun.
The male is a spectacular creature with black and white fringes on the legs and glistening palpi. We eventually found three males and a few females. Here are photographs of the male
Mexigonus “purple tomato”, male
and of the female
Mexigonus “purple tomato”, female
The male’s biggest claim to fame, though, is the purple sheen on his jaws (chelicerae). He guards the sheen modestly as he walks around, covering it with his palpi. It’s been therefore difficult to photograph. We managed to get a male to briefly do courtship, and of course then he spread his palps to show his purple jaws to the female, modesty abandoned. Here is a screen shot from the video of courtship. You can see the shine of purple just below his eyes.
Mexigonus “purple tomato”, courtship pose
We call this species “purple tomato” because his body form suggests he is related to the bright red species I showed in my first blog post about the expedition. That species was the first one we knew of its group, and so we have started referring to all of the species of the group as “tomatoes”, whether or not they are red. The Lachatao one is just the third member of the group we know, and its jaws compel us to name it “the purple tomato”.
The Lachatao day was a spectacular way to start an expedition.
Green ghosts
We chose as an important site to visit on this jumping spider expedition the summit of highway 175 as it goes north from Oaxaca City. There, at about 3000 metres elevation in a place called “Humo Chico”, is a foggy, damp elfin forest. In 1983 on my first trip to Mexico, I caught some elegant little jumping spiders there. Uriel named them “diamond” after the shapes of their markings. We can see that they are generally related to Mexigonus, but it’s not clear to us that they are actually Mexigonus, as they are more delicate-bodied than the other Mexigonus species we know. If they are Mexigonus, they would show the genus can evolve to such a body form, and so they are important for Uriel’s project. Their other point of interest is that two colours of males were found in 1983: one with the first two pairs of legs black, the other with just one pair of legs black. With fresh specimens, we could get new data to decide if they were Mexigonus, and whether the two forms represented different species.
We drove up on Monday from Ixtlán to this high elevation site, but it was misty, raining. We went first to the microwave station at the top, and found very little. All of us were discouraged. We decided to walk down to the main highway. I’m accustomed to jumping spider species staying hidden in their retreats, and so I expected that my anticipation in seeing these delicate spiders would be unrewarded.
And then a surprise occurred. In the drizzle, a jumping spider dropped on my beating sheet that I didn’t recognize at all. Pale and with long legs, it looked ghostly. When I picked it up in the vial I saw that it was a male with a big white moustache, and little black tips to the first legs. Beneath its white hairs the legs were a soft green colour. No jumping spider like this very distinctive species has ever been described. Here is the beautiful male staring boldly at my camera:
Mexigonus “green ghost”, male
Here are a male and female from above:
Mexigonus “green ghost”, male and female
We ended up finding 9 males and a few females of the green ghost Mexigonus. Even though I enjoy finding new species of any sort, whether brown and dull or spectacular, I have to admit that strange and colourful species excite me the most. Finding green ghost was a special moment.
But we didn’t find any “diamond” on our walk down to the highway. I was prepared to give up.
Shivering for diamonds
There was good news and bad news. The good news: we had found something new and special at Humo Chico, the green ghost Mexigonus jumping spiders. The bad news: we had not found any of our target, the delicate “diamond” jumping spiders. Disappointed, we went to the restaurant along the highway there, thinking to do a quick look before eating lunch. I’d found the diamond Mexigonus in 1983 near where the restaurant now stands, but there had been no restaurant then, and the area in the intervening years had been considerably disturbed by human presence (that was the reason we started instead in the undisturbed habitat along the road to the microwave tower).
As I went to try one last time, I was dripping wet and very chilled, for I’d not brought a jacket. When packing for a trip to Mexico, I had stupidly not imagined the chill of a rainy day at 3000 metres elevation. Just beside the buildings of the restaurant complex, I started beating the moss- and lichen-covered bushes. First beat, two specimens of diamond fell on my sheet. What relief, what satisfaction. They were still incredibly common at that particular spot, despite the degradation of their habitat. We got lots of specimens, including both forms of male I’d seen in 1983. Here is a male with just the first pair of legs black:
Mexigonus “diamond one dark”, male
And here is a male with the first two pairs of legs black:
Mexigonus “diamond two dark”, male
Now we can figure out whether they are Mexigonus, and whether the two forms of males represent different species. (I suspect so.)
In the end it was a very satisfying day at Humo Chico, finding our target diamonds and also new things like the green ghost. Shivering, the first thing I ordered at the restaurant was a hot chocolate.
Magic rediscovered
Arthur C. Clarke once wrote “Any sufficiently advanced technology is indistinguishable from magic”. There is an implicit shift of observer here, from those who make the technology (to whom it isn’t magic) to those who see the technology for the first time (to whom it looks exactly like magic). As an evolutionary biologist, I would suggest a generalization of this: “Any sufficiently advanced creative process generates products that are indistinguishable from magic.” Natural selection is one such creative process, and its products often seem as magic before we get a chance to study them.
As a 25 year old biologist I went on a grand expedition to Mexico with Stewart Peck, Jarmila Kukalova-Peck, Bob Anderson, and Mike Kaulbars. We drove from Ottawa to Chiapas and back to Canada. The trip was full of new experiences for me, but there was a singular moment I’ll always remember — the capture of a jumping spider on the road from Valle Nacional to Oaxaca City. Along a path in the cloud forest at about 1250 metres elevation, I found a handsome male spider with black, white and red markings, and a little brush of black hairs on the tip of the first leg that made it look like he was carrying a semaphore flag. When I put it in a vial to look at it, I saw a glow of delicate sky blue metallic hairs shimmering on the femora of his first legs. A sense of magic overcame me, the first time I’d experienced it. How could something like that exist without magic? The glow of blue was otherworldly. Of course, evolutionary biology has found that sexual selection can make such things exist, but when first encountering a marvel like this, magic springs to mind.
Thirty four years later I find myself in Mexico again, retracing some of the same paths. With considerable excitement we arrived to the same site to look for this blue-legged marvel. The team spread out in search of magic. In the first few minutes I found what I’m pretty sure are juveniles of the species, but no males. It was morning, and the ground and plants were still warming up, so we expected the males would take a bit of time to bother to wake themselves up and present themselves to the world. After perhaps an hour, Ricardo Paredes reported through our walkie talkies that he’d found a jumping spider with blue legs. I wasted no time in traversing the 100 m or so to Ricardo. In the vial he handed me, there it was, the mythical creature.
Here it is:
Mexigonus “blue legs”, male
This is what he looks like from above.
Mexigonus “blue legs”, male
Here is Ricardo at the site where he found the male hopping through small plants — right along the highway!
Ricardo Paredes León, where he found the blue-legged Mexigonus
And I have to put in another, gratuitous, picture of his blue legs. Note that both the first and second pairs of legs have blue femora.
Mexigonus “blue legs”, male
We didn’t find another adult male, but we did find some juveniles, including a young male (with one moult to go), which we will try to raise.
Magic still exists.
Bell-bottom pants
On the weekend, our #Mexigonus2017 jumping spider expedition stumbled on many bell-bottom pants, but not the kind you’re thinking of. After leaving Ixtlán, we drove south to San José del Pacifico, a little town in the Sierra Madre del Sur mountain range famous (so it seems) for its interesting mushrooms. Around our little cabin in the oak-pine forest at 2500 metres elevation, and then along our hike up the hill behind it, we found three different species of Mexigonus whose males have fringes of black hairs on either side of their first legs. It makes the legs look much thicker than they are, giving the illusion of bell-bottom pants.
The next day we found two more fringed species, giving a total of 5. Here they are:
Mexigonus species with fringes on the sides of the first pair of legs
OK, maybe they don’t look like bell-bottom pants to you. The fringes don’t actually get wider toward the tip (like a true bell-bottom), but rather they don’t taper as much as normal, so (to someone who is used to seeing spider legs taper) it seems as if they are getting wider. Believe me.
Here is another view of the five species, in the same sequence as above:
Same Mexigonus species with lateral fringes on the first pair of legs
What’s strange is that we didn’t find any species with lateral fringes in the mountain range north of Oaxaca city. Is there a local diversification of them in the Sierra Madre del Sur?
By the way, all 5 of these species appear new to science.
Crossing Tehuantepec
If you look at a topographic map of Mexico, you’ll see a series of mountain ranges extending from Oaxaca in the south through the volcano-studded centre to the northern ranges that extend into the U.S. Their cooler altitudes hold a fauna and flora with many relationships to those of the United States and Canada. Indeed, these Mexican highlands are the heart of North America for many groups of organisms, the place where their diversity is highest.
This broad network of mountains ends at one of Nature’s important boundaries: the Isthmus of Tehuantepec, a swath of low elevation cutting across Mexico at its narrowest point. The isthmus isolates the bulk of Mexico’s highlands from a smaller set to the east, those of Chiapas. The Chiapas highlands are rather different, biologically more related to those of Central American countries to the east and south.
Isthmus of Tehuantepec, shown with arrow (map from Google Maps)
We crossed the Isthmus of Tehuantepec last week, signalling the midway point in our #Mexigonus2017 jumping spider expedition, as well as a transition in our team members. We left Arturo Casasola behind in Ixtlán, and bade farewell to Ricardo Paredes on arrival in Chiapas. Both boosted the success of our expedition enormously. Arturo gave us a home base and guidance to perfect habitats, where we discovered the amazing green ghosts, purple tomatoes, and others. Ricardo not only did the driving, heroically, but he also added to our search effort. To my eternal gratitude, his sharp eyes allowed me to see the blue legged Mexigonus species again.
We spent the last week in Chiapas with two new team members. Jorgé León, a faculty member at ECOSUR, guided us to interesting habitats and facilitated our logistics, providing local knowledge that was vital for our work. Gerardo Contreras, a doctoral student at UNAM, not only has been another hero in driving us to far-flung places, but also a role model for us in going out fearlessly at all hours of the day (and we suspect night) to search the forests for the scorpions he studies. We have now finished with the Chiapas portion of the trip, and in the next few posts I’ll report on the discoveries that Jorgé and Gerardo have enabled.
Lagunas de Montebello
The geographical centre of my childhood is a point just across from Zephyr Island on the shore of Lake of Bays, in Ontario, Canada. There my family rented a cottage for a few weeks each summer throughout my childhood. It was a place of peace, of silver ripples at dusk, and a place of discovery, of salamanders and Sibianor and Maevia and Euophrys and Habronattus. My brother David and I never tired of its Nature.
A lake, surrounded by a green forest; the morning mist; a few people quietly working or sitting. A week ago I found myself in this familiar scene, filled with peace and an anticipation of discovery, at Lagunas de Montebello, a national park on the border with Guatemala. It’s at about 1500 metres elevation, a beautiful green cloud forest with epiphytes adorning many of the trees’ branches. After rousing from our cabins along the lake, we went to speak about our research plans to Odetta Cervantes Bieletto, director of the park, and her colleague Jose Alejandro Leon Mendoza (Alex). Alex, along with the park’s long-experienced Roberto, suggested a trail right near the headquarters. And so we headed out, beating sheets, sticks, and vials ready.
Within the first few minutes we got a surprise, the magical blue-legged Mexigonus! It turns out they were much more common than at the Puerto Antonio site in Oaxaca — at Montebello we got five males and a few females.
Montebello blue-legged Mexigonus
They might be a different species from that in Oaxaca, as the blue is muted, darker, and the face is red only above the eyes. We’ll answer the question of whether they are a different species once we get back to the lab.
We eventually found 5 species of Mexigonus there. Here are males of the other four:
4 other Mexigonus from Montebello
The top left and bottom right were new for our trip. We suspect that four of the five are new to science.
I’ll long remember the precious day at Montebello, not only for the new species of spiders, but also for its peaceful richness.
Of Foxes and Blue Beetles
Far in the south of Mexico, in Chiapas, is a set of mountains that parallel the Pacific coast. In the core of these mountains is El Triunfo national park, a hidden treasure that takes some work to get to. We drove to Jaltenango, took a 4×4 truck for a few hours to the village of Santa Rita at about 1200 metres elevation, then hiked up through the forest to a ridge at 2100 metres (our goods mule-carried), then down to the station nestled in a pastoral valley at 1950 metres. A bed, a rustic kitchen, and electricity. In a pristine cloud forest. Heaven.
Fox through the kitchen door, El Triunfo
Above is the view from the kitchen out onto the grounds. You’ll notice a grey fox. There were at least four of them, rather tame, hanging around whenever there was kitchen activity. Perhaps they had learned that food was occasionally dropped, or thrown.
The grounds around the station were cleared in part by the grazing mules. One of the first things we noticed were strange accumulations of shiny blue beetles on some small plants.
Blue beetles at El Triunfo
Here is a movie of the beetles; it’s quite a colourful sight. Perhaps mating congregations?
It took us a while to realize there was an ecological connection between the beetles and the foxes. Here are some animal feces deposited on the ground, about the right size for a fox, and with contents that make sense for foxes.
Mammal feces at El Triunfo
Notice the glints of blue. I felt like I’d walked into someone’s house and discovered there was more drama than visible at first.
The Call of the Quetzal
We had been collecting in the El Triunfo cloud forest for an hour or two, following the Costa trail south, when we arrived at the crest of the trail, at 2100 metres elevation, before it descends toward the Pacific coast. Up to that point, we had been finding only a single species of Mexigonus, a brown and creamy-yellow one:
Brown and yellow Mexigonus from El Triunfo, nice but not too exciting
Then, at about the same moment, Łukasz and I both found dark brown Mexigonus females that looked unfamiliar. We wondered: what do the males look like?
Unfamiliar dark brown Mexigonus female.
Male and females of many spider species look quite different. Male jumping spiders often bear fancy plumes and colours they show during dances to the females. And, of course, their genitalia are different. Because we taxonomists find many useful characters to distinguish species in their genitalia, we want to find both male and female specimens of each species in order to get a complete characterization.
But, I have to admit, arachnologists tend to be biased toward the males for scientific reasons — the species are easier to distinguish by the males — and for aesthetic reasons — the males are sometimes spectacularly ornamented. Seeing those two dark females was like hearing the call of an unfamiliar bird but not seeing it. We knew there was a kind of male in this forest, perhaps right in front of us, that we had never seen before. Would the males have muted colours, or would they burst resplendently from the forest like a colourful quetzal?
Knowing there were more out there, including the unseen males, we tried to guess their precise habitat. The females had been on small trees with some mosses and suspended dead leaves, and so we tried shaking various such trees over our sheets, seeing what fell out. After about an hour, we had found some juveniles, but not adult males. We were discouraged.
And then, he appeared. He fell on the beating sheet, his two long and furry front legs instantly marking him as a male. On the sheet, from above, he appeared as a nondescript grey.
Male of the grey-brown Mexigonus is finally found!
Once he was in the vial, I turned my hand lens on him.
Male of Mexigonus “quetzal”.
His face was red. The “fur” on his front legs shone a brilliant metallic green and blue and orange. He was a miniature quetzal. I was over the moon.
One of his most noticeable features is the wide fringe on the sides of his first legs, like the bell-bottomed spiders from Oaxaca. These fringes make his first legs appear very wide from above, but very narrow from the side:
Mexigonus “quetzal” male
Notice the blue glow from his right legs! Under some lights, the face positively glows orange-red:
Mexigonus “quetzal” male
(I’m sorry. I can’t stop from adding more and more photos.) Generally he hides his colours, but Uriel and I put him in front of a female and this is the pose the male took:
Mexigonus “quetzal” courtship pose. Wow.
In fact, the true quetzal, the bird that is both real and mythological, that gives proof to the magical realism that is Mexico, lives as well at El Triunfo. Is it the emblem of the park. We were told that we might see one were we to wake up early enough. We didn’t. We were fully satisfied with our little eight-legged quetzals.
We hiked down from El Triunfo on Wednesday, thankful for our time in the pristine, verdant wilderness, and for the park staff’s professional help. Our visit was supported generously and capably by Janette, Arcenio, and the rest of the El Triunfo team.
The Weavings of Chicahuaxtla
In my first post about our #Mexigonus2017 expedition, I showed a photo of a brilliant red Mexigonus that was one of the inspirations of the study. We had found it in 1998, less than a kilometre northeast of San Andrés Chicahuaxtla, in Oaxaca. After our fulfilling time in Chiapas, we managed to arrange a visit to the area of Chicahuaxtla on the last day of the Oaxaca-Chiapas expedition, as we were driving back to Mexico City. I was filled with anticipation. I so much wanted to see the beautiful red “tomato” species again.
Early last Friday morning, we drove to Chicahuaxtla, where we met Amador Tello Rojas and Heladio Fernández Martinez. We weren’t able to go back to the exact site at which we’d found the red “tomato” beast in 1998, but Amador graciously allowed us to go to his family’s land, which was about 800 metres northwest of the 1998 site. The habitat was similar, oaks and pines in a fairly dry landscape.
We started to look on the ground and bushes beneath the oaks, and soon found a couple of small juvenile spiders that we thought were the red beast. But, we needed an adult male to be sure. After a long, frustrating search, a male finally fell onto my sheet. I was so excited — finally I’d see the red beast again! But, something was wrong. It should have had stout dark front legs; the one on my sheet had long delicate front legs with a little “feather” at the end. I got it in the vial, looked at it up close, and realized I had a brilliantly red spider, but different from the 1998 one. Here he is:
Mexigonus male from Chicahuaxtla
He’d certainly turn heads if he walked into a room.
Finding a new form so close to the red “tomato” beast confused me. It occupied what seemed to be the same microhabitat as the 1998 species, and it lived only 800 metres away. Do the two forms make contact between the two sites? They look closely related — do they hybridize? To add even more complexity, Jose Luis Castelo, a colleague who has done research on Mexigonus, noticed that our 1998 collection from Chicahuaxtla included a third fancy species, one that looked like our purple tomato. Three exquisite species of Mexigonus within one kilometre?
Are Chicahuaxtla’s mountains full of many beautiful Mexigonus, each occupying a small territory? Could it be that decorated Mexigonus exist as a pattern of many forms and colours spread across the landscape, evolved slowly over many generations, like the beautiful woven huipiles for which Chicahuaxtla is known?
In the end, we didn’t collect at the 1998 site, and so my desire to see the “tomato” species again remains unfulfilled. But, instead, we found a new and beautiful form. What we thought was a simple search has turned into a lot of questions about the diversity of ornamented Mexigonus in this mountain range.
The Rainbow of Mexigonus
#Mexigonus2017 is over, and I’m back in Canada. I’m left with many memories of Mexico, strengthened friendships, great samples of new jumping spider species, and good data. As the first of a few retrospective posts here, I present The Rainbow of Mexigonus:
The Rainbow of Mexigonus
We saw the whole visible spectrum among the colours of Mexigonus. The red was intense; the orange was common; the green was delicate; the blue was stunning; the purple was unexpected. You’ll notice I didn’t mention yellow. For some reason, strong yellow is not obvious in Mexigonus adornments (except as a momentary flash in the metallic iridescence of the “quetzal” Mexigonus).
This is what the whole spiders look like, in the same sequence as the rainbow. The caption says who they are. You’ll notice that the multicoloured “quetzal” gets three appearances!
The cast of colours:
| “quetzal” from El Triunfo | “red moon” from Chicahuaxtla |
| “orange ghost” from San Jose del Pacifico | “orange yellow” from Montebello |
| “big moss” from El Triunfo, female | “yellow face” from San Fernando |
| “green ghost” from Humo Chico | “quetzal” from El Triunfo |
| “blue legs” from Puerto Antonio | “quetzal” from El Triunfo |
| “purple tomato” from Lachatao | “purple tomato” from Lachatao |
The second one down on the left side is worth mentioning — it’s an orange ghost! You may remember the green ghost from Humo Chico north of Ixtlan. When we headed south to the Sierra Madre del Sur and collected the “bell bottom pants“, we also found what we thought was the same green ghost species. But closer inspection showed it to be a different species — even fuzzier, without the white moustache, and with legs orange instead of green. Here is a better picture of him:
“Orange ghost” Mexigonus
Mexigonus is just so diverse, and almost all undiscovered.
Racing Stripes
People who know jumping spiders know that adult males of many species look different than females. Females are usually modestly coloured, but males may have bright colours they show to the females in elaborate dances. Some commonly-seen differences, however, don’t seem to relate to courtship. In many species, the males have distinctive black and white stripes, but the stripes are on their backs, which the females don’t see during the male’s courtship. Why do the males have stripes?
One of the most handsomely striped species I’ve ever seen is an undescribed Mexigonus from eastern Mexico. We caught it during our #Mexigonus2017 expedition at Sierra Gorda national park. Uriel calls this species “tuxedo” for the fancy suit the males wear. Here it is; on the left is the male, on the right the female.
Mexigonus “tuxedo”.
A similar male-female difference in stripes is seen in many other genera of jumping spiders, including some familiar in Canada such as Pelegrina, Eris, and Habronattus.
My best guess for the stripier pattern of males is that they move more than females. We have data from a few species of jumping spiders to indicate that males wander more, traversing a lot of territory in a day (looking for females?), while the females are relatively sedentary. An idea that’s been around for a while (e.g., look up Jackson, Ingram & Campbell 1976) is that what is good camouflage for an animal depends on how much it moves. If an animal sits still a lot, then it’s more cryptic if it’s mottled or spotted. If, on the other hand, an animal spends a lot of time moving forward, then longitudinal stripes can provide a disruptive visual effect that makes it harder for predators to see the moving animal. Hence, mobile males have stripes, homebody females not.
Compact spider photo setup
The photos of beautiful spiders in my posts about our #Mexigonus2017 expedition were taken with a new camera, the first I’ve had in many years. For the previous 12 years I’d taken spider photos, tens of thousands of them, with a comical ancient Pentax Optio with a hand lens glued to it. Even though it’s old and low resolution (3 megapixel), it worked for me. In order to have a hand free for wrangling the spider, I need to be able to hold the camera in one hand and manipulate it easily. I also need to take photos of dozens of specimens each evening. Standard DSLRs are too awkward and heavy, so much so that I wouldn’t be able to take photos of all the species I want to photo, were I to use a big DSLR. I’d rather have low resolution photos than none at all, and for that reason I stuck with my tiny camera for many years.
A friend’s small mirrorless Olympus impressed me, and convinced me it was time to change, and I’m so glad I did. My new camera is an EM10-Mark II, with basic 60 mm macro lens and the standard TTL flash, which I mounted with polymer clay and zip ties as shown here. It’s a compact package I can manage mostly with one hand. It took me a while to figure out the settings (manual focus, etc.), but I’m very pleased with the results. The photos aren’t aesthetically as good as those of the current generation of good salticid photographers (I don’t use diffusers, etc.), and I could improve the arrangement to reduce shadows, but the photographs serve my purposes well. On one photo of a male that was hanging upside down, I could see the shape of the embolus of his genitalia. That’s good enough resolution for me!
Olympus EM10 — Mark II with Macro and flash, for taking spider photos.
Farewell to Mexico and #Mexigonus2017
It’s been almost three weeks since I got back from our Mexico jumping spider expedition, and I’ll give one last post to wrap up. The trip was a full of wonderful spiders and people and places. I have already thanked some of those who helped, but I’ll repeat and add others, who helped so much: For logistics, thank you Tila, Griselda, Ricardo, Gerardo, Arturo, Jorge, Juan Pedro, José Luis, Fernando, Alex, and Janette. For sharing your salticid expertise and experience, thank you Uriel, Łukasz, Dariana, Valentina and Ellen.
I should have known the trip was going to be a success before we hit the road. At the UNAM university bookstore, as we were stocking up at the start of the trip, there was this little souvenir puma — the mascot of UNAM — labelled as a biologist, with a spider on one arm and a beetle on the other. What better omen?
UNAM Puma biologist with spider and beetle
No, I didn’t buy the souvenir. Why, I don’t know. I have an aversion to (almost all) knick knacks.
Wayne Maddison Lab 