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Dinoponera: Giant Killer Ants from the Amazon

5 Apr
Giant ant with big jaws.

Head and jaws of Dinoponera gigantea. (Photo courtesy Israel Del Toro)

Today’s post is about Dinoponera, which is a really freaking cool genus of ants, containing some of the largest species of ants in the world.  It is brought to you in recognition of my labmate Paul Lenhart’s new paper revising the genus, and also the following conversation:

Paul: What would I have to do to convince you to shamelessly plug my new paper on your blog?

Alison: Oh, okay, I can do that.  Send me some cool pictures.

Collin: At least ask for money.

Giant dinoponerine ant with stinger.

Dinoponera quadriceps with stinger visible. (Photo courtesy Israel Del Toro)

So some cool things about these South American ants.  The name Dinoponera translates roughly to “terrible devil,” or possibly “terrible painful evil thing.”  As I mentioned, Dinoponera can get quite large: Dinoponera gigantea workers get up to 3.6 cm, almost an inch and a half in length.  The stings and venom of these extremely predaceous ants are very strong and have been suggested to possibly be more painful than those of the infamous “bullet ants” (whose sting, according to popular lore, is like getting hit with a bullet).

New species of giant dinoponerine ant.

Newly described species, Dinoponera hispida. (Photo courtesy Israel Del Toro)

Dinoponera is one of a few ponerine ants which has lost the morphologically distinct queen caste.  Instead, to quote Paul directly: “one of the younger females becomes dominant, beats the shit out of the other ants, and her ovaries swell up and she becomes queen.”

Because this status is flexible, she is sometimes also referred to as the alpha female.  If she dies the process begins again, and another worker can step up to fill her place.  New colonies are formed when one of the beta females absconds with a cohort of workers, a process called fission.  Average colony size varies by species, and ranges from as small as about 10 workers to as large (if it can be called large) as 120 workers.

Giant winged dinoponerine male ant.

Winged male sexual of Dinoponera gigantea.  The genitalia have been removed for analysis.  (Photo courtesy Israel Del Toro)

The males are winged, but the females, since they are not a distinct sexual caste, are wingless.  Instead they wait at the entrance of the nest and mate with visiting males.  This is when things take a turn.  After mating, the female chews through the male’s gaster (basically his belly) to release herself. The male’s genitalia is left inside her.  This may function as a temporary mating plug, preventing her from mating with other males.

Nature! I can’t make this stuff up.

Sawtooth "chainsaw penis" of dinoponerine ant

The penis valve of newly described species, Dinoponera snellingi. (Photo courtesy Paul Lenhart)

It is possible the genitalia of the males are partially adapted for this “plug” purpose, as many have a barbed, sawtooth edge. In fact, one of the new species Paul and his coauthors described is most easily recognized by what Paul described as a “chainsaw penis,” a particularly strongly lobed “penis valve” with teeth running the length.  The newly described species is named Dinoponera snellingi, in honor of the late renowned entomologist and colleague, Roy Snelling.  I have no further comment on this subject.

Roy Snelling

The inimitable Roy Snelling.

One of the other new species, Dinoponera hispida, was described from specimens that were all collected in a single region of northern Brazil, called Tucuruí.  The only known location of this species has since been completely flooded, due to the construction of the Tucuruí dam, making it possible that this species became extinct before it was ever described.

Many insect boxes in the shelves of an insect collection.

The LA County Museum Holdings. (Photo courtesy P. Lenhart)

To write this paper, Paul and his coauthors looked at over 350 specimens and sought loans from collections all over the new world, as well as places like Germany and Italy, where holotypes (world representative specimens of the species) were preserved.  He also visited Ecuador and Argentina.  Paul said it was really cool to see types collected as far back as the 1800s.  On the other hand after years of work and thousands of person hours spent on this project he has still never seen a live Dinoponera ant.


Scientist observing ant taxonomy.

The life of a taxonomist: Coauthor Dr. Bill Mackay observing Dinoponera specimens at California Academy of Science. (Photo courtesy P. Lenhart)

Did I mention Paul has a new paper out?