Scott Powell’s comment on my post about ant-like jumping spiders provokes me to take a break from our current field trip in Mexico to write a post about one of the most stunning cases of mimic-model matching I’ve seen in salticid spiders. On a trip to the Dominican Republic in 2009 we found a fair diversity of jumping spiders of the genus Peckhamia. In one locality we found this ant and this species of Peckhamia.
In another locality we found this ant and this species of Peckhamia. Notice that the front legs of the spider are tipped in red, just as are the sides of the face and the mandibles of the ant. Wow.
In yet another locality we found this beautiful species of Peckhamia. We didn’t see a correspondingly red ant, but perhaps a reader can advise us if such exists in the Dominican Republic?
The wonders of being at a field station… A chachalaca through the bathroom window.
Back in 1998 when I was last in Chamela, we found two species of Habronattus that were new to science. They are still new, which is to say, we haven’t gotten around to describing them yet formally and giving them proper scientific names. They are two of my biggest targets on this trip, and I’m happy to report that despite it being the middle of the dry season, we’ve found adults of both.
The first was given a code name ROBRT in my paper with Marshal Hedin on molecular phylogeny of Habronattus. It’s a species that seems unclear whether it wants to be in the viridipes group (erect scales between the posterior eyes, courtship behaviour) or the clypeatus group (black central stripe under the abdomen, backward triangle marking on abdomen). What has surprised me is that I now see it has the same strange pattern inside the eyes as I recently posted for H. aztecanus of the clypeatus group. Check out the eyes here:
By the way, in that photo notice the third leg with the bumpy green and red patella. It strikes me that the eye pattern and third leg are usually in focus at the same time when I take the photos. Crazy idea: could the eye pattern actually be a courtship ornament that the male displays to the female in coordination with motions of the third leg?
The second undescribed species was give the code name CHMLA by Marshal and me. It’s a sweet little species from forest leaf litter. The face has a cute little pair of stripes that make them look as if they have a rodent-like grin. For the first time I got photos of the female of CHMLA:
Now that we have both, along with the common H. zapotecanus and H. cambridgei, we have achieved an important goal of this trip: to get fresh specimens of several common Mexican species groups of Habronattus, for future phylogenetic work.
I’ve been quiet for a few days, which is a good sign in field work: many new specimens to process will keep me away from the computer. To break the silence I’ll show two ants, which despite Heather’s gasteropost and subsequent comments, have a certain cuteness to them. But of more interest to me than the two ants (sorry, myrmecologists) are some jumping spiders that look a whole lot like the ants.
First is a cephalotine ant, which I find rather stylish with its grey robotic body. Below are a Bellota and a Peckhamia, both of which have independently evolved a resemblance to it.
Bellota. I like how the head of the spider seems to correspond with the thorax of the ant, with the thickened first legs of the spider corresponding with the head of the ant. (Why the spider’s name comes from the Spanish word for “acorn”, I don’t know.)
Peckhamia. While many antlike jumping spiders wave around the first legs as if they were the antennae of their model ants, Peckhamia belongs to a group that waves around its second pair of legs.
The second ant is a Pseudomyrmex, the long, thin, quick ants common here in Jalisco.
And this is not an ant but Synemosyna. Even after decades of looking at jumping spiders, when I find a Synemosyna I have to look closely to confirm that it’s actually a spider. This particular species has black spots corresponding to the eyes of ant — within the black spot is one of the spider’s eyes, but the eye is much smaller than the spot.
Why is it a good idea for a jumping spider to look like an ant? This hasn’t been well enough studied to answer the question with confidence. For most antlike jumping spiders, the mimicry does not seem to have evolved to fool the ant (e.g. to eat the ants, like a wolf in sheep’s clothing). One possibility is that it’s a good idea to make a predator think you are an ant, as many predators avoid ants because they can sting or bite and are accompanied by many friends who will do the same. Check out Heather’s blog for some insects that have evolved to look like ants.
All spiders, with one known exception, are carnivores. That exception is Bagheera kiplingi, a jumping spider whose relatives seem quite normal, but which has taken up a mostly vegetarian lifestyle. It does this by eating the nutrient-rich Beltian bodies on acacia trees that are tended by ants. If you Google “Bagheera kiplingi”, you’ll find references to studies by Christopher Meehan and colleagues.
The last time I saw the species live was in 1983, and following its fame I wanted to see it again. When Heather spotted a bullhorn acacia as we were driving near San Mateo, Jalisco, we decided to stop the car for a moment. Without even opening the window, I saw a Bagheera kiplingi crawling on the plant. Woohoo! Here are a male and female that we found. The female has normal jaws that hang down from the face, but the male has jaws (chelicerae) that stick forward, instead of down.
There’s a thrill I get when past scientific work yields a prediction that works. On a little road in Jalisco, nature was in order, with Bagheera and ants and acacia all living together.
As thrilling as it was to find Bagheera kiplingi, there was a cost, as Heather recounts in her blog post about Gasteroposting.
Yesterday we found live specimens of opilioacarid mites, Heather’s main target here in Chamela! They are a strange group with many traits that have been interpreted as ancestral for their branch of mites. We had not found them over several days at Chamela. Then, on Saturday, Heather found some dead ones in a litter extraction. And, yesterday, we found 17 of them walking around under rocks! Go to Heather’s blog for more details, including what she suspects is the first video every posted of an opilioacarid. CNN should be phoning momentarily.
Dick Walton asked about the strange pattern in a Habronattus aztecanus eye, and so I’ll post another photo.
The pattern is deep inside the eye. As you look into a jumping spider eye, you normally see either black or a honey-brown colour. You see black if he/she is looking straight at you and thus you are looking straight down onto his/her retina. You see honey brown if the spider is looking off to the side, because then you are not looking into the retina, but rather to the side of the tubular eye. The big eyes of a jumping spider are not globes like ours, but rather long tubes, only the deepest bit of which is the retina.
However, in species of the Habronattus clypeatus species group, which includes species such as H. clypeatus, H. dossenus, H. californicus, and H. aztecanus, there is a part of the eye that has this strange pattern when you look down into it. It is presumably in the inner wall of the eye.
Anasaitis brunnea, from the Dominican Republic
No, this is not a post about undertow or getting sand thrown in my eyes. It’s about Habronattus. In an earlier post, I hinted that I was not that excited by finding Habronattus contingens in Puerto Vallarta, as there is a very similar species in Canada. This is what those H. contingens from Puerto Vallarta looked like. Note the creamy white face and fluffy front leg (Update: better photo of face added).
We wanted to explore beaches down here, near Chamela, and so yesterday entomologist Enrique Ramirez guided us to a well-preserved beach with student Alejandro Estrada. Here are Enrique, Alejandro, and me at the beach. Note that when I speak of a “well-preserved beach” I’m not talking about the relatively sterile sand. I’m speaking of its richness beyond the sand, like the beautiful tree-sized cacti.
At the beach, I was mostly interested in finding out whether H. aztecanus lived this far south. I was finding what I thought was H. contingens, but I wasn’t that interested in them, so I wasn’t paying close attention and we only collected a couple. When we got back from the beach I got out the hand lens and was shocked to look at their faces — they seem to be something quite different! Their faces are black, not white, and overall they are much darker than H. contingens. Are they a new, separate species, or are they just a strong geographic variant of H. contingens? Tomorrow we are going to another beach, and this time I will pay attention to this strange thing related to H. contingens!
When I was last in Jalisco, in 1998, we were looking mostly for Habronattus. It was quite a group — Tila Perez and her students Jose Luis Castelo and Fernando Alvarez, and myself and my postdoc Marshal Hedin and student Gita Bodner. The trip was a wonderful success, and laid the groundwork for much of our research on Habronattus. We visited many memorable sites, but the one place dearest to my heart was the biological field station Chamela, on the Pacific coast about 100 km southeast of Puerto Vallarta. It’s in a seasonal tropical forest of short trees that lose many of their leaves in the dry season. We were warmly greeted and supported by the station director Ricardo Ayala and by the infrastructure provided. And we found some very cool spiders.
And so it was with great anticipation that I drove with Heather up the hill to the station a few days ago. Under the directorship of Jorge Vega, the station has continued its development. The well-equipped facility is vibrant: amazing biodiversity and interesting researchers. And the food is great! This morning we climbed the tower to take a panorama photo. We’re looking forward to our few weeks here.