A photographic journey to the ants of the Ecuadorian Chocó

Ecuador is one of the places with the highest biodiversity on Earth. Despite the country’s relatively small size, it encompasses a variety of diverse regions. Most notably is the Amazon to the West of the Andes, which has one of the highest ant diversities in the world. Yet, there is also a piece of evergreen tropical rainforest on the other site of the gorgeous mountain range called the Chocó. Its fauna and flora is astonishingly different from that of the Amazon, and it bears closer resemblance to that of Central America, to which it connects through Colombia and Panama.

A Photoblog compilation by Phil Hoenle

The Chocó region is under enormous human pressure, with lots of forest being chopped down mainly to create space for oil palm plantations. Now, only a tiny fraction of it is left. The Chocó in Ecuador received surprisingly little scientific interest, despite of its very high biodiversity with many endemic species. Barely anyone ever collected ants in the northwestern tropical lowland.

This means there are lots of fascinating ants left to study for me and my colleagues! I am currently doing my PhD thesis on ant diversity in recovering forests within the reserve “Río Canandé“, which is owned by the environmental NGO “Jocotoco”. Their immense effort to preserve this area is impressive, and we are very grateful to have their never-ending support for our scientific projects. This is a very exciting work because I can easily encounter lots of ant species that are rather unknown.

Here, I want to share some impressions of the coolest ants of the Canandé.  

Typical habitat within the Canandé and its neighbouring reserve Tesoro Escondido.

Army ants

I want to begin with one of my favourite study subjects, the army ants. Fortunately, there are lots of them in the Canandé!

One steaming hot afternoon I watched a leafcutter ant nest of Acromyrmex being raided by Nomamyrmex esenbeckii right in front of the research station. Here, you can see the leafcutter ant defending itself –in this case unsuccessfully. Still, even the heavily armoured predators can get wounded, and the worker in the picture is already missing a part of its hind-leg.

One of the biggest highlights of the trip were the very few encounters with the predominantly subterranean Cheliomyrmex andicola. Not much is known about their biology, but other researchers reported that they eat giant earthworms and scavenge corpses. Their mandibles and their sting are quite impressive!

The tiny Neivamyrmex cf. asper is a leaf-litter raider. Neivamyrmex is the species-richest army ant genus in the Neotropics, but they are very seldomly observed, supposedly because they are smaller and have a more cryptic lifestyle than the other army ants.

The leaf-litter ant fauna

The leaf litter is probably the easiest habitat to assess in the forest, and harbours a large chunk of the total ant diversity in any tropical forest. Those ants are very diverse in their appearance, and some are really good at hiding; many of them move very slowly and are tiny, which makes them hard to spot. I therefore often rely on Winkler leaf-litter extractions to find and photograph them.

This is Cyphomyrmex costatus, a small fungus-farming ant. Their fungus has typical mycelia.

Cyphomyrmex cornutus, on the other hand, grows yeast fungus. Notice that the yeast pebbles are stacked on top of a beetle elytron, which can be found in basically all nests of this species.

These are the impressive trap-jaws of Acanthognathus!

The mandibles of these Strumigenys are like long forceps. Despite the weird shape, they are still able to handle their brood with care.

Lenomyrmex foveolatus is one of the weirdest ants of the Canandé. Not much is known about its biology.

Protalaridris armata. To find out more about them and their weird mandibles, you should absolutely read the paper by Lattke et al. (2018) on them.

Prionopelta amabilis is a common leaf-litter ant in the Canandé. According to Hölldobler & Wilson (1986), it is a hunter of Diplura.

This Gnamptogenys sp. from the minuta group has a strongly vaulted gaster. On first sight, this is reminiscent of the ant subfamily Procetariinae, but it actually belongs to the Ectatomminae.

Hylomyrma is a genus known to live in higher elevations, and this one here is common in the leaf litter above 600 m. 

This cute and minute ant is a queen of Discothyrea sp. They are known to specialize on arthropod eggs.

The Canopy

The canopy is one of the most important habitats for ants in tropical rainforests. It is more difficult to access than the leaf litter, however. Recently fallen trees are the best and simplest spot to get an overview of the ants that live there.

Procryptocerus sp. have a strong body armour but are surprisingly fast nonetheless.

Dolichoderus cf. validus builds beautifully woven nests in the canopy. Here, a worker collects the plant fibres necessary for nest construction.

Myrmelachista might be small, but the colonies can grow huge and this depicted species dominated the canopy of a whole tree.

This big orange Megalomyrmex bidentatus is probably the largest Megalomyrmex of the Canandé.  Megalomyrmex ants are known for their heavy chemical weaponry (alkaloids!). The nest was located on a large tree trunk between some dead leaves.

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