Thursday, June 25, 2015

A grassland surprise

The end of this week marks the halfway point my time here at the Smithsonian.  Our Guiana Shield project is humming along and the discoveries have continued.  It’s clear that all the expeditions to the Guiana Shield over the past decade and a half have been worth it.

Since most of the expeditions went to places that hadn’t previously been surveyed for ants, virtually all of the specimens represent new occurrence records.  Many of them also represent new country records.  And a few had never been collected from anywhere in the entire Guiana Shield.  And that’s not counting the dozens of undescribed species in the collections.

Here are just a few of the interesting specimens we’ve gone through over the past couple weeks.

The ridiculously cute Discothyrea sexarticulata is a specialist predator of spider eggs.  It’s a widespread species that occurs from Central America south to Paraguay, but until recently it was unknown from the Guiana Shield.  As far as I know, the first Guiana Shield records were a single individual collected in the Lely Mountains of eastern Suriname in 2005 and a specimen that we collected in rainforest near the Waiwai village at Parabara Landing in Guyana in 2013.

We collected this Discothyrea sexarticulata worker, the first record for the species in Guyana, in rainforest at the edge of the Rupununi Savanna in 2013.

The aptly named Anochetus horridus was for decades known only from Brazil.  Then in 2005 twelve specimens were collected from the Lely and Nassau Plateaus in eastern Suriname.  A subsequent expedition collected it again from Kasikasima Mountain in the southeastern part of the country.

The horrid trap-jaw ant (Anochetus horridus) nests in rotten logs and uses its fast-moving spiny mandibles like a bear-trap to capture prey.  This specimen from eastern Suriname represents the first Guiana Shield record for the species.

But my favorite find so far is from our expedition to the grasslands of the Rupununi.  Using pitfall traps in tall grassland at the foot of the Kusad Mountains we collected the rare Gnamptogenys ammophila.

The predatory ant Gnamptogenys ammophila is unique in being the only grassland specialist in its genus.  Until we collected this specimen in Guyana the species was known only from a small area in Venezuela.

Since it was first described in 1986 the species was known only from high altitude grasslands in a single watershed in the Gran Sabana of southeastern Venezuela.  Our find nearly 30 years later, 250 miles away at over 1,000 meters lower altitude, greatly extends the known range of this elusive species.

Leeanne and Samson and I—the Rupununi ant team—had no idea  two years ago, as we waded through that sea of grass waving flies away from our eyes, exactly what we would find.

Turns out it was pretty cool!

Friday, June 19, 2015

Guiana Shield discoveries

I’ve spent the past five weeks sorting through ant specimens at the Smithsonian.  It’s been slow and at times tedious, but rewarding.  We’re learning a ton and making interesting discoveries.  And as of last week our photography efforts are in full swing, providing me with endless material to share here on M2M.

We now have enough species identified and photographed that we can easily appreciate the diversity found in the Guiana Shield, even within a single genus.  The turtle ants (Cephalotes species) are one such case.  These heavily armored tree-dwellers come in a variety of shapes and colors.
Turtle ants (like this Cephalotes atratus) are easily recognized by their shield-shaped heads that they use to plug up their nest entrances in stems and branches  

We collected this C. atratus from the Parabara savanna in Guyana in 2013
I collected the smaller and hairier C. pusillus in the nearby Kusad Mountains on the same expedition…

…while this C. opacus came from the upper reaches of the Palumeu River in southeastern Suriname.
My new favorite turtle ant is the flat and pinkish Cephalotes persimilis.  Instead of spines, pearly translucent ridges extend along its sides.
Cephalotes persimilis is a savanna specialist that nests in scattered trees and riverside forests surrounded by grassland.  I collected this specimen from a lone tree in the Parabara savanna.  As far as we know, the wet Amazon Basin isolates the Rupununi population of this species from the rest of its species’ range over 1,000 miles away in dry areas of southern Brazil, Paraguay and Argentina.
I collected this C. minutus at night in our camp at the foot of the Kusad Mountains…
…and this aptly-named C. spinosus at the Kuyuwini River, while waiting to catch a canoe to the Waiwai village at Parabara Landing.

All this diversity is lovely, but my favorite find so far came earlier this week.  We found the first  Guiana Shield record of the oddly-shaped Dolichoderus inpai.  This species was previously known only from the Western Amazon in Brazil, Colombia and Ecuador, but our specimen is from 1,000 miles to the east in the Kasikasima Mountains in Southeastern Suriname.  Before this week, this specimen sat unrecognized in a tiny cardboard box, known to the world only as “Dolichoderus sp. 3.”

What’s even more exciting is that no publicly accessible image of the species exists, aside from partial line drawings in an identification key.
We believe this is the first photograph, and the first Guiana Shield record, of the odd Dolichoderus inpai.

It’s been an exciting five weeks.  I can’t wait to see what the rest of the summer has to offer.

Friday, June 12, 2015

Learning to photograph

This summer’s Guiana Shield project combines a lot of my favorite interests.   Not only does it involve geography, natural history, and a little conservation, but I get to take a broad view and work with entire ant communities.

The Guiana Shield is a big region with lots of habitats and hundreds (maybe thousands) of ant species.  And we get to study them all indiscriminately.

The big development this week is that we’ve finally started photographing the species.  Emma has been learning to use the microscope camera and the imaging software and her photographs are amazing.

The species we’ve photographed so far all came from my trip to Guyana's Southern Rupununi savanna in 2013.  But like the Guiana Shield in general, the diversity in form and lifestyle among just these first few specimens is stunning.

The tiny, fuzzy, and nearly blind Acropyga smithii lives its life underground away from the sunlight.  It makes a living by tending and feeding off of herds of root-sucking mealybugs.

At the opposite extreme, the gliding turtle ant Cephalotes atratus is large, spiny, and heavily armored.  It nests in trees and lives its life in the sunny rainforest canopy.  If a worker falls off a branch she can use her legs to glide through the air and return to her home tree and colony, rather than fall to the ground and face certain death alone on the forest floor.

Azteca species also live in trees.  They’re small, quick, and aggressively defend their territories from invaders by biting and spraying clouds of noxious chemicals.

Allomerus octoarticulatus takes plant-living to an extreme.  It nests inside of small cavities provided by specialized ant plants.  The ants are minuscule but have a powerful sting that is painful to any animal (even a human) that might disturb their host plant.

Back on the forest floor, leafcutter ants like Acromyrmex landolti survive by growing and harvesting fungus gardens.  To feed their fungus crop, they harvest vegetation from the surrounding area, chew it into a pulp, and place it in their gardens.

The largest leafcutters, like this Atta laevigata soldier, have scissor-like mandibles and massive head muscles for cutting through thick leaves.

The trap-jaw ant Anochetus bispinosus, in contrast, uses long thing mandibles with sharp curved teeth to capture and kill animal prey that it hunts in the leaf litter.

These are just six of the 400 or so species we hope to identify, map and photograph.  You may have noticed that we're proceeding in pseud-alphabetical order, and we're still at the beginning.

There’s a ton of diversity left to document.  I just hope we can finish it all.

Monday, June 1, 2015

Smithsonian for the summer

I’m doing something a little different this summer.  Instead of fieldwork like my fire ant project in northern Florida or my purple martin work in southeast Oklahoma, this summer is devoted to museum work.  I’ve got a small NSF grant to spend the summer at the Smithsonian National Museum of Natural History in Washington, D.C.  The goal—to catalogue, photograph and map the ant species of the Guiana Shield.

I look forward to reconnecting this summer with some of my favorite natural areas around D.C., like Great Falls Park along the Potomac River

The Guiana Shield region of northern South America contains the world’s largest remaining area of unbroken tropical rainforest.  There’s one stretch where you could walk through 500 miles of the Amazon rainforest without crossing a road.  It’s also one of the world’s most biodiverse areas, chock full of species and indigenous human cultures.

This large and relatively intact region presents one of humanity’s last great opportunities to protect entire landscapes.  In many ways it’s also unexplored.  As far as ants go the rainforests and grasslands of the Guiana Shield are one of the richest and most poorly studied places on the planet.

That’s where we come in…sort of.

Over the past 15 years a few organizations have been working to study the ants of the Guiana Shield.  They’ve surveyed different sites to collect specimens, identify new species, and locate areas worthy of protection.  My expedition to the Southern Rupununi savanna in 2013 was part of that trend.  But the efforts have been piecemeal, conducted by different researchers working for different organizations with different goals.  The resulting specimens—the records of those expeditions—were likewise scattered in different places.

Over the past decade and a half several expeditions have surveyed ants from across the Guiana Shield

Now we’re bringing all those collections—hundreds of species from nearly 30 locations across Guyana, Suriname and French Guiana—together into one place.  And we’re working to combine all those different survey results into a single open access database, complete with high quality photographs of every species.   A list of regional ant species, along with a map of where they occur, would allow us to study evolutionary patterns across the Guiana Shield and help us better plan protected areas.

With that in mind, through the course of the summer we aim to catalogue, photograph, and map over 400 ant species collected from sites extending across 900 kilometers of the Guiana Shield.  It builds on my previous Suriname and Guyana work but is much, much bigger.  It just might be the most ambitious project I’ve undertaken in my scientific career, and I’ve got just over two months to finish it before I head back to Oklahoma in the fall.

Fortunately, I’ve got a lot of help.

I’m working in the lab of Ted Schultz, ant curator here at the Smithsonian.  He and his lab are lending us space, equipment, specimens and plenty of help.  I’m also getting some help from Leeanne Alonso, a specialist in biodiversity exploration who I’ve worked with on and off for two years now.

Aside from that, there’s a team of people working with me directly on the project—Tiago, Chris and Emma.  Tiago, a budding ant researcher, is an undergraduate from Brazil and one of my former entomology students at OU.  Chris is a neuroscience major here to learn a bit of taxonomy.  Finally, Emma, an undergraduate with a passion for science communication, is our resident photographer.  A few others may drift in and out during the summer.

It’s a great group of people.  This is my third week here at the Smithsonian and it’s already shaping up to be a productive summer.