13 replies to this topic

[RushmoreAnts]

There are two distinct Tetramorium species in my area. The slightly smaller species has some workers which have a red thorax as well, just as T. tsushimae is always described. 

[NickAnter]

It is possible.  What you could do is get a dead specimen, preserve it, and send it to someone with a microscope, if you don"t have one, to get a positive ID. 

[ForestDragon]

I agree with what Nick says

[CheetoLord02]

Tetramorium tsushimae and Tetramorium immigrans are not easy to tell apart. Usually tsushimae will have a redder thorax than immigrans, however this is not consistent. One way that was suggested to be an indicator was polygyny, as tsushimae are believed to be polygynous where immigrans are pleometrophic.
In mid July at Barbara Key Park, IL, myself and some other anters collected 11 Tetramorium sp. queens and each took a number of queens. My personal 3 queen colony raised several generations of all black workers before fighting and being left with one queen. However, no fighting has happened in any of the other multi-queen groups, so it may have either been a fluke in my group or it was simply T. immigrans and not T. tsushimae, and we will see fighting in those colonies soon.
Really we need to find a better way to tell the two species apart, as it is quite likely that T. tsushimae is far more widespread across the US than we think. If you are noticing 2 distinct worker colors it could either be a color morph (ex. Crematogaster cerasi being fully black or having a red/black variant) or it could truly be 2 distinct species.

[RushmoreAnts]

I currently have a founding queen, who is 6.5 mm. I’m thinking she may be tsushimae due to her smaller size.

[AnthonyP163]

 

It's a bad iPhone video, but it shows what I need it to. A TON of those workers had a red thorax, and they seemed a tiny bit smaller than immigrans.

 

I took worker specimens from an immigrans colony on my property as well as these cf. tsushimae down the road and looked at them under my microscope. There is no constant 'defining feature' on tsushimae that discerns them from immigrans. However, in this case, I noticed that all specimens (8) of the cf. tsushimae had sparse and shorter gaster hair compared to the (~12) immigrans.

 

Along with the above morphological differences, the colony was different in behavior. I saw tons of them on that morning, where they could've been flying, but I struggled to gather enough specimens that afternoon.

 

I have caught 2 smaller queens this year. I have kept them isolated, to avoid mixing species or getting one species killed.

 

They are thought to have been established for 32 years, starting in St. Louis. This is a perfect place for them to start, since they can spread to small and large towns alike through major roadways going in, and out of St. Louis. Presumably, this is how we find them in northern Illinois, and how I found them in Southeastern WI, and, perhaps, how you found them in South Dakota. I hear rumors of polygynous Tetramorium in Colorado nowadays as well.

 

There are already records in Springfield, MO, Nashville, TN, and unofficial records of them in other places. I truly think the amount of research done on them is insufficient. Their ability to live in prairies and knack to tend root aphids makes them an even greater problem than immigrans, and it doesn't help that they're polygynous.

[RushmoreAnts]

There are two distinct Tetramorium species in my area. The slightly smaller species has some workers which have a red thorax as well, just as T. tsushimae is always described.

I have observed colonies within 50 feet of each other, who were of similar size. One colony had noticeably larger workers, while the other had smaller workers. Their alates were slightly different in size as well. Also, the larger and smaller alates will fight, while the smaller alates will cooperate perfectly.

[RushmoreAnts]

I'm going to get some more queens and test to see if they're polygynous. 

Edited by AntsDakota, July 2 2020 - 9:23 AM.

[Mdrogun]

I'm going to get some more queens and test to see if they're polygynous. 

Please keep in mind while testing this, that Tetramorium immigrans pleometrosis has been observed to last for 9+ months in certain instances. This is the problem in saying that Tetramorium tsushimae is identified by being polygynous. There is no black and white polygyny in ants, sometimes colonies will stay polygyne for a long time, even if the species is not technically 'polygynous'. 

[Antkid12]

I may have seen T. tsushimae in my yard, one colony I saw had a ton of workers with red thoraxes.

Edited by Antkid12, July 2 2020 - 11:39 AM.

[RushmoreAnts]

I may have seen T. tsushimae in my yard, one colony I saw had a ton of workers with red thoraxes.

Well, these have only been recorded in large numbers in the Midwest so far.

[ANTdrew]

I may have seen T. tsushimae in my yard, one colony I saw had a ton of workers with red thoraxes.

Let’s hope you’re wrong.

[Kaelwizard]

Every Tetramorium worker I have ever seen has had a red (sometimes very close to head and gaster color) thorax, and all of the colonies I have found have been monogyne.

[RushmoreAnts]

Ants_Dakota caught a bunch of immigrans queens which are 1-2 mm larger than mine. They get along fine with each other, but when I tried introducing one to my queen, they fought, indicating different species.