Profile of the ant genus, Leptogenys in Singapore:
Brief description of Leptogenys ants
Leptogenys are a huge genus of ants under the subfamily, Ponerinae and are found in abundance throughout tropical and sub-tropical climates, making Singapore a nice spot for them. These ants are slim in body shape, ranging from a few millimeters to 1.5cm and possess sickle-like jaws, along with a sting. Leptogenys are sometimes called 'army ants' but do not confuse them with the ants under the subfamily Dorylinae for they are not related. They are called 'army ants' as some species are normally seen in huge numbers forming trails across the forest floor, however there are also species that prefer to work beneath the leaf litter and soil. Like the army ants under the subfamily Dorylinae, they swarm their prey in great numbers, biting and stinging (being a member of the subfamily Ponerinae, Leptogenys ants possesses a sting) them. Unlike the army ants in the subfamily Dorylinae however, they are quite picky and mostly specialize in a few types of prey in the wild such as isopods, which their sickle-like jaws make quick work of. Most species have ergatoid (a wingless reproductive caste that workers could even take up, sort of like gamergates) queens, meaning a female Leptogenys alate would be very rare or impossible to find. They do have a drone caste, where males fly to other colonies to mate with the ergatoid gyne after being brought inside the nest by the workers. Due to the replacement of winged queens in this genus, founding a colony is not possible and the only way to get a colony is through legal trading between hobbyists, along with catching a colony not from state land or in a park (protected areas).
(Picture: Leptogenys processionalis trying out a piece of mealworm)
Author's comment: I apologise if the pictures are low quality! These are old media and are mostly cut from videos, I'll try to update this post some time with the better images.
Care of Leptogenys ants
If you have overcame the difficulty of obtaining a colony, you will be faced with another issue, which is their care. The main issue with Leptogenys is that they are picky eaters, being specialized in certain prey items in the wild such as isopods. In the hobby, we can't offer such foods in such high numbers and most of the time have only commercial feeders such as crickets and mealworms. I've found that House Crickets (Acheta domesticus) are rejected most of the time, despite being offered either whole or cut up. However, nymphs are usually accepted, with chances of them accepting being higher if the nymph is live as shown in the pictures on the right. The feeder I had the most success with are Red runner roaches (Blatta lateralis) which they accept immediately as shown below with my colony dragging half of a red runner back to their nest. My friends had success with cut-up mealworms and I have not tried superworms. It's really interesting to see to see one worker make contact with the food item, followed by another and soon the whole colony starts flooding out. I could see why they're sometimes called 'army ants'.
In terms of setup, fortunately, Leptogenys are not hard to house. They are normally shallow diggers and nest under wood, rocks or in crevices. One important factor to note while housing these ants is humidity which they require a high level of. Moisture retaining substrate and constant misting comes to mind. I always recommend peatmoss as a substrate as it holds moisture well and mimics the pH of the soil in a rainforest, making it comfortable for forest species such as Leptogenys. White aquarium sand or perlite can be mixed in to provide visibility for ourselves and make the substrate more varied for the ants to work with. Ytong and plaster formicariums are recommended if you're going for a non-naturalistic setup for they hold moisture well. Place a little bit of substrate in the formicarium and hydrate every 1-2 days for ideal humidity levels. I cannot stress how important substrate is important for genus of ants under the subfamily Ponerinae, considering how they aid the larvae in spinning their cocoons and most species have 'slippy-feet', meaning they have trouble walking over smooth surfaces, Leptogenys is no exception. If you're going for a naturalistic set-up, it could be as simple as a piece of wood for them to nest under which is what I did for one of my colonies. With their moisture-loving nature in mind, decorations such as moss could be added and serve as water-holder, along with plants as they could be kept hydrated often. Going for the complicated side, Leptogenys is a good candidate for a paludarium with a wide land space. (Pictures: A colony of Leptogenys processionalis being temporarily housed in a test-tube)
Species of Leptogenys in Singapore (Under construction!)In my knowledge, there is about 3-4 species of Leptogenys but I have only encountered 2 while there are still findings yet to be properly identified in Singapore.
This is the most common and possibly the smallest species of Leptogenys you would come across in Singapore. These ants measure at about 7-8mm and are a shiny brownish-black. They are normally found under rocks and wood in the wild. I've encountered some colonies nesting near water-bodies such as small rain-ponds. I've been using this species as examples for all the information above and this is the only species I've ever kept so far. They are not that demanding compared to other uncommon ant species in the hobby, just keep the care information above in mind.
(Picture: Leptogenys processionalis trying out a piece of mealworm)
I've only encountered this species once and never again for the 2 years I've been in this hobby. I was on the search for Odontomachus rixosus to photograph, as I squatted down to observe one, an individual Leptogenys diminuta sprinted by and luckily, I managed to scoop it up. This is a large species of Leptogenys, measuring to be about 1.2cm with an orange tip where the stinger is, possibly the largest species of Leptogenys in Singapore. They look really much like a skinny Diacamma. According to a friend who have encountered a colony of this species in the wild, they are really aggressive when it comes to food and defense. I'm pretty sure for their size, they are a force to be reckoned with. I hope to be able to encounter this species again and observe them for myself. (Pictures: the individual I caught.)
Leptogenys myops and pompiloides:
These are two species found in recordings of Singapore biodiversity and the specimens are drones, not workers. I believe these two species are small and forage beneath the leaf litter, making them really hard to find. From what I know, pompiloides has a brown tint compared to processionalis while myops is reddish-brown, looking more like some sort of dracula ant. I've yet to encounter these species and since they are recorded in online databases, I believe these two are present in Singapore.
(Leptogenys myops: https://m.singapore.biodiversity.online/species/A-Arth-Hexa-Hymenoptera-000224)
Overall, Leptogenys prove to be a very interesting oddball in the Ponerinae subfamily with their ergatoid gynes and 'army ant' behaviour. Due to their nature, they are a really fun species to keep and observe as they swarm their prey, unlike your off-the-mill individual foraging workers of other Ponerines such as Trap-jaws, but each species have their own charm definitely. A big thank you to my friend Yuxuan and his classmates, who owns the Euponera sharpi blog (http://euponera-sharpi.blogspot.com/2018/05/guide-to-keeping-euponera-sharpi.html) for the macro shots of their Leptogenys processionalis colony! Of course, a big thank you to you, dear reader and I hope that you've learnt something new from this blog or that it helps you with your colonies! If there is any queries regarding this post, feel free to email me or leave a comment! - Isaac Ong.