17 replies to this topic

[wook]

Some of you might know that I am huge fan of Formicinae, especially Camponotus and Formica genus.
Well, lately, my focus is on Formica genus, especially on sensu stricto et raptiformica groups.

Most common species around here is Formica sensu stricto rufa pratensis var. nigricans.

First available use of Formica rufa pratensis nigricans is by Emery, 1909.
Name origin: Formica lat., ant; pratensis lat., meadow; nigricans from nigra lat. black or dark.

However, some scientists disagree with idea that this is new species, so it's officially called Formica sensu stricto pratensis.

Key differences between F. pratensis et F. nigricans are pilosity, color and behavior. For example, F. pratensis is more common in north Europe and their number decreases further on south while F. nigricans are rare in north and their number increases to south of Europe.
F. nigricans is more hairy, they have something like eyebrows on top of their heads, hairs are long and they can be commonly confused by F. lugubris. Actually, only difference between F. lugubris et F. nigricans / pratensis is in location. F. lugubris is upland type of ant while F. nigricans / pratensis are lowland types of ants.
F. nigricans is darker than it's sister F. pratensis and smaller specimens can be completely brown (dark), like F. cinerea/balcanina.

Literature says that both species (F. pratensis et nigricans) can be found in same nests in central Europe. F. pratensis is monogynous or oligogynous (rare) and monodomous while F. nigricans is rather polygynous or olygogynous and polydomous just like it's upland sister.

On dead specimens is hard to see any difference without microscopic / dna identification because to see differences it's needed to see behavior of whole colony.
Like most of rufa group ants, they are hunters too. They will hunt from wasps to other ants, especially alates.

When they hunt other winged insects, first target is head, if they can not reach head, they will try to cut wings off until backup is there. They will spray acid easily, they are fearless and they have great sight.

They are only two species of European F. s.str. that can have two nuptial flights per season which can develop two separated generations of alates (one in spring and other in autumn).
This type of strict wood ants are known raider of F. cunicularia et cinerea/balcanina.
Queens are easily recognizable by pilosity on their gasters.



(Formica pratensis var. nigricans worker)


(Formica pratensis var. nigricans queen and workers in background)


(Formica pratensis var. nigricans queen)


(Formica pratensis var. nigricans workers)

Today I had to visit remote colonies and it was really nice to see them active at +7C.


(Formica pratensis var. nigricans workers)


Sources:
- Phil a.k.a. lusatica
- bwars.com
- prof. dr. I. Petrov
- Seifert B. 1992 - Formica nigricans Emery, 1909 - an ecomorph of Formica pratensis...
- C. A. Collingwood 1979 - The Formicidae (Hymenoptera) of Fenoscandia and Denmark

[wook]

Formica nigricans attack on Vespula vulgaris

[dspdrew]

Nice!

[wook]

You still want them?

[dspdrew]

Yeah, those are awesome.

[wook]

Luckily they are not aggressive as Raptiformica.

[lusatica]

Very nice summary and pictures of the F. pratensis/nigricans situation, wook! And how very lucky you are to have them in abundance right on your doorstep. I have to cross the English Channel just to get a sight of pratensis!

 

Have you ever seen any of the pratensis sensu stricto (Seifert's "p-morph") in your area? As you say, it's still a debatable point among some experts whether they should be separate species or not, despite Seifert's comprehensive assessment and conclusion that they are ecomorphs of a single species. It would seem that some other species have been split up on apparently more subtle morphological differences than these two. Lasius platythorax/niger or L. alienus/psammophilus perhaps as examples.

 

All three castes of nigricans and pratensis show obvious differences, but especially so the queens, where the very hairy propodeum/petiole contrasts with the hairless condition of the same parts in pratensis.

 

Mixed nests do occur, but could perhaps be explained by pleiometrotic founding by queens of two related species.

 

When I get time, I will make some image-stack photos of pratensis vs nigricans queens (Cedric Collingwood kindly sent me some of the latter).

[wook]

Thank you lusatica. Well, nest on my doorstep is nothing comparing to one place I've found on one hill (like 20 large and few small nests on 500m^2).
I've noticed two variations of F. nigricans, one is less hairy than other, and more red, but still more hairy than F. pratensis, other one, can have completely black workers (big ones), but they are not aggressive as first one.

Other difference is that I've noticed this ants only near pine trees (not on open) while less hairy ones don't care if they are in open (like meadow) or in forest.

I've not evidenced anywhere F. pratensis p-morph, but friend of mine did (little bit norther than here and lower in altitude).

As far as I am concerned, pilosity and regional prevalence are reasons enough to split species, or to conclude both keys into one and split up from F. lugubris. I really had hard time identifying those ants, but I enjoyed.

 

Mixed nests, well, if F. pratensis p-morph are so strictly "monogyne", then F. pratensis n-morph is slave species for them because I've not seen n-morph monogyne nest yet.

 

I would love to see those photos.

 

Little bit off topic, but, two days ago I've found Formica cunicularia queen wandering around. I am sure she was kicked out of the funding chamber she shared with other F. cunicularia queens. What do you think?

 

I am upgrading my photographic abilities in matter of days, so I hope I will be able to

[wook]

Updates:

(Formica p. var. nigricans small nest mound.)

 

(Formica p. var. nigricans workers with very young and black workers amongst them.)

[lusatica]

Nice pictures again, wook.

 

Is that a typical nest of the F. nigricans in your area, and how often do you notice what may be new foundings?

 

There is some fascinating evidence that F. pratensis queens may use a "pass" consisting of a captured Serviformica worker, in order to gain acceptance by a Serviformica colony, in the same way that Chthonolasius queens do to gain favour with Lasius s. str. workers. See http://www.miiz.waw....ratensis-zm.pdf .

[wook]

Thank you again, big black ones are rare, but nests that contains them are next to pine tree and they are usually mounds while they do have paths to flat nests.
I will take some videos soon.

In this inter-connected nests, black ones can appear in flat nests too, but their number is higher in mound nests.
Whatever this is, seems to me like one big/huge happy family.

Flat nests are usually old ones (I assume they crashed inside) while mounds are usually younger or new nests on top of old ones.
There's one mound, leaned on pine stump that is really huge and strong and old, there's holes in ground all around the nest.
They do grow in altitude rather than in width, while other, don't grow at all...

I think F. nigricans rather like to setup new nest from mother nest like bees does. But, anything could be possible. I have several Serviformica colonies and I could test it...

However, Serviformica workers do forage around some F. nigricans nests, without any problems/conflicts with workers.

 

(Come little closer - F. nigricans.)

 

Little update:

(Formica pratensis var. nigricans from nest which do not contain big blacks)

[James C. Trager]

Nice pictures, Wook. I am also quite a fan of this genus. I look forward to seeing how Seifert treats them in his upcoming (2015) English-language revision of his "Ameisen" book...

[wook]

Nice pictures, Wook. I am also quite a fan of this genus. I look forward to seeing how Seifert treats them in his upcoming (2015) English-language revision of his "Ameisen" book...

Thank you again. I hope I will see some Polyergus too somewhere...

I am looking forward for link to that revision.

[nurbs]

Regardless, those are really cool looking ants.

[wook]

Thank you nurbs.

We're having very warm winter, which is naturally very unusual for this location, instead of -20C right now we have more than 13C.
I am observing behavior of ants at two different locations, first is location in my backyard and second is in the forest of very windy hill.
18.02.2014. - Formica sp. from uphill is very active, new ants are taken outside to be heated up on every single nest. Formica pratensis var. nigricans in my backyard is still in the nest. They are very small, but still it's very warm.
19.02.2014. - Formica sp. rushing to get last rays of sun, soon enough rain will come.
25.02.2014. - Formica p. v. n. in backyard is awaken, they are not very active, but they looks good. Other species are waking up too, Myrmica sp., Lasius niger, Formica balcanina et rufibabis. Seems like Formica cunicularia is not intending to wake up just yet.
26.02.2014. - I was uphill giving yolk with sugar to ants, especially small nests. Found another 3 satellite nests around one huge. I've noticed that each nest has own Pinus sylvestris tree where they are tending aphids. This conclusion has been made by positions of satellite nests. Each nest is in warmest part of ground around pine tree.
Appendix:

(Formica s.str. sp. ants on nest mound catching sun.)

(Formica s.str. sp. worker eating yolk with sugar.)

[Crystals]

I find it interesting that they all gather on the surface of the nest to warm up.

 

I have never seen that in any of the species up here.

A handful might sun themselves and go back into the nest or go foraging, but not en mass like that.

 

I love their coloration.

[wook]

Thanks Crystals, well, you see, most of the ants on top are very very young. some of them do not even walk yet.

As I stated in previous post, "all nests have own pine tree", well, seems like some have even several.
Photos:

(Nest 1)
Nest 1 is old and large nest. It is in sunniest part but also in most windiest part. I believe that is the reason why it do not have many workers nor satellite nests.


(Nest 2)
Nest 2 is probably very young and it is on top of old, dead mound. Nest 2 is also in coldest part, sun do not reach very often to there and it's turned to the east.


(Nest 3)
This nest is small satellite nest fund by daughter from the nest in next picture.


(Nest 4)
Nest 4 is very active, probably in best place as it's warm most of the day and it also do not have wind to cool it down. It has many satellites around 6 in total of which two are temporary I believe.


(Nests 5)
Two nest, hidden in long grass, they are very small and they are satellites of large Nest 4.

As visible from photos above, each nest has own pine tree. There's no single nest on open area, but also, none of them are in deep forest.
What's more interesting, there is couple of wild apple trees and domestic plum trees, but seems like ants ignore those.

[wook]

Close up samples of two queens, worker and male.
https://drive.google...Y29RSlA4OG5SblU
Notified: prof. dr. I. Petrov, dr. G. Karaman