Updated: Nov 4, 2020
Carebara is a genus of ants containing many members. Most of the researched species in this genus are found in Asia and Africa. But there are also species found in the Americas. Below is a list of species found here in the Americas according to my rudimentary research:
As one can observe from the list above, Carebara is actually very diverse in the Americas. However only Carebara longii (Cocina compex; underlined) is native to the United States.
Carebara longii gyne collected in Texas. Notice the erect hairs on the abdomen.
Most, if not all, of the Carebara in the Americas are pretty much unstudied, as collections are few and far between. Behavior observations for American Carebara are even less common, most of the data coming from papers scattered across the various databases, libraries, and collections of the world. Most of our research from Carebara come from Dr. Fernando Fernández (Universidad Nacional de Colombia).
Recently I had the opportunity to travel to Austin, Texas. While I was there I did many things, including touring the entomology collection at UT austin, meeting Dr. Alex Wild, attending my mother's graduation, and... of course, searching for ants. I found quite a few ants right outside the hotel I was staying in, including Dorymyrmex flavus, Brachymyrmex sp., cyphomyrmex rimosus, and solenopsis invicta.
However I observed quite a few ants on they day I went and visited Zilker open space, and Zilker botanical gardens. Collecting species like Atta texana, Camponotus cf. decipiens, and the spotlight of this article Carebara longii.
There are 15 valid collections of this species according to California Academy of Science's Global ant Database. I naturalists states another 6 observations, I can only verify 4 of these as one of the queens was missing an abdomen and the one worker observed was not of good quality. My observation is cited on inaturalist as well including some of the data from collection.
So where did I find this queen exactly? luckily I observed the collection coordinates with a photo, so I was able to add this to my inaturalist observation. Below I have included the useful information
Interestingly enough, the gyne was collected under a log next to (~4cm away from) a larva of a Lucanus sp. stag beetle, which is likely just a coincidence, but still an interesting observation, nonetheless. It was found in a mixture of leaf litter, loamy soil, and decayed wood soil.
The nest of Carebara longii can be found up and to the right of the yellow leaf in the photo. beetle larva found out of frame to the left.
According to my observations this species often resorts to thanatosis (playing dead) when disturbed. I have observed this behavior many times but it usually was correlated with disturbances or vibrations. This is likely an effective strategy in the wild, as this species can avoid predation if it doesn't move. It appears to appreciate moist nest temperatures and lays more eggs when soil is present in it's nest.
Thanatosis as a defense mechanism in Carebara longii is fairly common according to my observations.
Carebara longii queen in her newest nest that I specially designed even with custom soil.
I observed this queen to be very active, often attempting escape when given the chance. I observed that it also curled up when dropped. This is likely a defense mechanism to avoid disturbances on the ground. The queen also reared up on her legs a few times after recovering from a disturbance. this is likely to make the ant look larger.
Carebara longii queen rears on her forelegs.
Overall, I believe this species is likely cryptic in nature, or at least it founds its nests in leaf litter. Most collections (oddly enough) take place between september and october, which could mean that even workers are elusive unless the time for nuptial flight comes around. I estimate that this species likely has two nuptial flights or alternating ones between mid-late September (Sept. 12-28), and mid October (Oct. 12-18). I also support the hypothesis provided to me by Fernández, that this species likely has a major caste that hasn't been observed yet. The fact that this species has not been found in large numbers also suggests this is the case. If the species was subterranean, like other Carebara they could be vacated from their nests by army ants like Neivamyrmex, or Labidus.
I think this species likely will face difficulties in the future as fire ants invade more of their habitats, because queens are more likely to get found and eaten by the workers of Solenopsis invicta as queens found colonies.
Carebara longii profile.
Carebara longii queen with eggs, this species seems to be very resilient when it comes to rearing young.
The mysterious case of Carebara longii in Costa Rica.
Recently I was shown this image of a queen found in costa rica. After reaching out to John Longino at University of Utah, an expert on the region, I was informed that the queen belonged to another species Carebara urichi. who's queens look almost identical in person.
Fernández's paper: https://antwiki.org/wiki/images/6/65/Fernandez_2004a.pdf
Carebara longii records: https://www.antweb.org/browse.do?genus=carebara&species=longii&rank=species
My Inaturalist observation: https://www.inaturalist.org/observations/35103468
Observation database (personal): https://docs.google.com/spreadsheets/d/1pezshUFFtkCkpE9WsQviPsgxmBPgosuf5cWEhuNAudI/edit#gid=0