Leptogenys elongata and the mysteries of a new world Isopod specialist
Leptogenys elongata is a species of ant with a new world range spanning from Texas to west Louisiana, and down into Mexico, It may be present elsewhere. They are a species that appear to be unanimous with central texas forests, and they are especially common in College station where I found plenty of colonies!
A portrait of Leptogenys elongata
Leptogenys elongata: A review
leptogenys elongata occurs primarily in Texas and Mexico, however, there are records from Oaklahoma and range estimates place this species as occurring as far west as Arizona, and possibly as far north as Colorado. I although highly doubt that leptogenys elongata is present in Colorado unless present in caves.
Habitat and nesting habits
Leptogenys elongata is commonly found in the forests of central and eastern Texas, where it can be found nesting under 1 out of every 10 logs or objects found on the forest floor. The caveat is that their nest is generally very dry for forest soil, with lots of porous holes in the ground, where the brood and pupae are stored under objects. Flipping a rock or log with a colony underneath is often only made apparent by a pile of pupae and a few workers transporting the pupae from time to time.
Leptogenys elongata with pupae, slightly soaked with water.
Newly eclosed workers, pupae, new queens, and males are all often found in the top level of their nest.
Leptogenys elongata possesses a set of interesting jaws used for it to help consume its prey. In addition, it also posses rather large eyes. These features often give it a fascinating, yet somewhat creepy face and smile.
The smile of leptogenys elongata is visible in this portrait.
A close up of a Leptogenys elongata specimen, showing the interesting jaws, eyes, and face punctuation.
Leptogenys also possesses very long, skinny legs used to assist in the transport of brood.
In addition to the long legs, Leptogenys elongata also has interesting anatomy when it comes to sexuals within the colony. Males appear a yellow-orange color and look nothing like most ants, this is common for male ants, and male Leptogenys look like almost every other male ponerine out there.
A male leptogenys elongata specimen wanders across a bbq skewer, in addition to the 5 I found at a black light I also found one inside a colony.
Queens are hard to recognize due to being ergatoid, or wingless. Other popularized ergatoid queens include army ant queens (Dorylinae) which have wingless queens born in the nest. Ergatoid queens of Leptogenys are usually only recognisable by their much larger abdomen
An ergatoid gyne in a colony, this one is newly eclosed.
Leptogenys elongata is very interesting because they prey almost exclusively on Isopods (AKA roly-polies, pillbugs, or sowbugs). I say almost because I saw one colony take advantage of an exposed termite nest and earwig eggs when flipping a log. They prey on many different types of isopods I'm sure but I saw these one hunting Armadillidium vulgare specifically. In captivity, I was able to feed them Porcellio scaber as well.
Leptogenys worker and Armadillidium vulgare isopod prey
Leptogenys elongata primarily seems to hunt in groups but sometimes singular workers can be seen scouting out prey, as is evident above. once prey paralyzed they sometimes generally take care of them by themselves.
Two Leptogenys workers dispatch an Armadillidium vulgare isopod
A Leptogenys worker attempts to drag prey to the nest.
I personally was not able to find the center of a larger nest to take a picture, but after the Leptogenys elongata workers dispatch their prey they bring it to the nest where their larvae consume the isopods.
Reproduction in Leptogenys occurs when virgin queens wander around after being ejected from the nest, they mate with males, likely during the night when you find most males, and then found a colony from there. It's unknown whether leptogenys follow similar lifestyles in while residing in caves or if they have more troglobitic lifestyles when living within caves. There was apparently another species of Leptogenys found in caves other than L. elongata.
An ergatoid queen hardens in the nest
Colonies don't always get along, often they raid each other or fight when put in close proximity to one another. The same goes for new queens once they are evicted.
Leptogenys workers from different colonies fight with one another. Also, the egg in this photo belongs to an earwig, The workers collected them when the nest was exposed.
Leptogenys workers from different colonies fight with one another.
John Latkey's paper on Leptogenys: https://www.antcat.org/references/132941
Alex Wild's website, he is a great photographer and the curator at UT Austin entomology collection: www.alexanderwild.com
Here's an interesting one, this is wheeler's paper from 1904 containing most of the recorded biology on the species: https://www.journals.uchicago.edu/doi/pdf/10.2307/1535818
There may be mistakes in this article, I will attempt to update and remove as many as I can.