20 replies to this topic

[PetsNotPests]

1. Location (on a map) of collection: Los Angeles, CA
2. Date of collection: July 10 
3. Habitat of collection: Indoors, on a hardwood floor
4. Length (from head to gaster): 5 mm
5. Color, hue, pattern and texture: Brown-black, striped gaster, 2 petiole nodes (Monomorium???)
6. Distinguishing characteristics: None 
7. Distinguishing behavior: None
8. Nest description: None
9. Nuptial flight time and date: None

 

 

 

 

Attached Images

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Edited by PetsNotPests, July 12 2021 - 8:54 AM.

[ANTdrew]

Looks like Monomorium alright. Nice find.

[NickAnter]

Does the antennal club have 2 segments? If so it is Solenopsis truncorum. 5mm is rather large though, possibly remeasure?

[PetsNotPests]

Does the antennal club have 2 segments? If so it is Solenopsis truncorum. 5mm is rather large though, possibly remeasure?

4.5-5mm is her exact measurement, and along with dual nodes, i'd say Monomorium.

[NickAnter]

Check the antennal clubs please. All Myrmicines have a post-petiole by the way. Its not a trait specific to Monomorium.

[PetsNotPests]

Check the antennal clubs please. All Myrmicines have a post-petiole by the way. Its not a trait specific to Monomorium.

I know. The nodes are much more pronounced than say a S. molesta queen though. From what I can tell, there's nothing out of the ordinary about her antennae ether. 

[NickAnter]

Its not going to look out of the ordinary. Its just a matter of segments, and you have to look under decent magnification to see it(the magnification shown in your images would be enough if the clubs were in focus). Its by far the easiest and most reliable way to distinguish the two.

[gcsnelling]

Solenopsis truncorum, Monomorium queens along the coastal areas typically do not have wings. That looks like a two segmented club.

[Manitobant]

Solenopsis truncorum, Monomorium queens along the coastal areas typically do not have wings. That looks like a two segmented club.

that species doesn’t exist, and there is no way this is a solenopsis carolinensis queen (the species it is a synonym of)

[NickAnter]

It clearly does exist. Just because some myrmecologist decided to ignorantly synonymize it, does not completely remove its valididty. Solenopsis truncorum flies from 3-6pm, compared to carolinensis, which flies in the dark hours of the morning. Furthermore, truncorum queens and males are black, considerably different than those of carolinensis.

[Manitobant]

It clearly does exist. Just because some myrmecologist decided to ignorantly synonymize it, does not completely remove its valididty. Solenopsis truncorum flies from 3-6pm, compared to carolinensis, which flies in the dark hours of the morning. Furthermore, truncorum queens and males are black, considerably different than those of carolinensis.

i also can’t find any literature about this species, which confuses me.

[NickAnter]

Its because to my knowledge it wasnt really studied. I have studied the species as extensively as I can, but unfortunately, its very difficult to ID molesta group workers in the field, so it makes colony observation, aside from nuptial flights, rather difficult. I have what I believe are 3 fertile queens (2 for sure) and I am hopeful that I will be able to better study the species in captivity, after my past failures with the species.

[gcsnelling]

Who placed it in synonomy?

[NickAnter]

I can't seem to find that out, its something that's been irking me for some time, especially considering the erroneous nature of the synonymization.

[Aaron567]

S. truncorum was synonymized with carolinensis in Pacheco & Mackay, 2013. The Systematics and Biology of the New World Thief Ants of the genus Solenopsis (Hymenoptera: Formicidae):

 

"Forel (1901) separated the workers S. texana race truncorum from the S. texana race carolinensis by the lighter color, smaller size, shorter scapes and a narrower petiole. Direct comparison and measurement demonstrates that they are both similar in coloration, approximately equal in size, the scapes are actually slightly longer in S. truncorum and the petiole is equal in length. The females are apparently identical, although only the female from the type series of S. truncorum was available for study. Thus, S. texana truncorum is proposed as a junior synonym of S. carolinensis."

 

The type series of S. truncorum was collected in North Carolina. This paper also claims that Solenopsis validiuscula (a western species) has been falsely called S. truncorum in several pieces of literature since 1950, which I think could've possibly led to this eastern US taxon becoming something thought to occur in western states even if it doesn't. I can't find any literature relating to S. truncorum after this 2013 revision.

 

Luckily, AntWeb has a type specimen of a S. truncorum queen imaged in their database: CASENT0908856 Solenopsis carolinensis

 

To me at least, she looks just like the little yellow queens that come to blacklights in the early morning in the southeastern states; head shape, eye size, and ocelli size seem to match up very well. S. validiuscula is a species with larger, brown queens that are similar to S. molesta but have some consistent differences. Considering this, are we sure Californians aren't collecting S. validiuscula instead of S. truncorum?

Edited by Aaron567, July 14 2021 - 2:00 PM.

[NickAnter]

I have seen validiuscula in person, and their queens are extremely bulky, and about 6mm in length. Most truncorum queens are around 3-3.5 from my experience. Also, these workers are tiny... Barely over 1mm long, and a much lighter yellow than validiuscula. Validiuscula are at about 2mm.

That is a video by CheetoLord, which shows a validiuscula queen.

Edited by NickAnter, July 14 2021 - 3:22 PM.

[gcsnelling]

It would not shock me to find at some point in the future that the California thing is an undescribed species.  I tend to take any of Mackays work with a rather large grain of salt.

[NickAnter]

I have a queen, worker, and a male if it needs to be described.

[gcsnelling]

Take care of the specimens, it may be some time before there is someone crazy enough to undertake the task.

[NickAnter]

Currently in 70% ethanol hand sanitizer, with the main other ingredient in the sanitizer being glycerin. Don't have 90% ethanol unfortunately.