Key to Formica species of the subgenus Formica of Greece
This key to workers is from Borowiec and Salata 2022. Each terminal couplet is followed by comparative remarks that are specific to the Greek ant fauna.
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1
- Occipital margin of head with more than 10 erected setae. Mesonotum and propodeum usually with numerous erected setae . . . . . #2
- Occipital margin of head without or less than 5 erected setae. Mesonotum and propodeum without or with only few erected setae . . . . . #3
2
return to couplet #1
- Pitch-black large patch on promesonotum with sharp margins. Frons perfectly matt. Setation of mesosomal dorsum and gastral tergites denser, gaster on dorsal surface always with numerous erected setae . . . . . Formica pratensis
Formica pratensis and Formica lugubris are the only members of the nominative subgenus with distinctly setose occipital margin (Formica polyctena and Formica rufa have to or at most 3 short setae on occipitum). Formica pratensis is the most setose species with distinctly higer number of erected setae on head and mesosoma than in F. lugubris. Especially setation of gaster in F. pratensis is more evident as its Greek opulations have setation of first two gastral tergites limited to the anterior slope of the first ergite while in F. pratensis the whole surface of all tergites is densely setose. Aditionally, in F. pratensis dark spot on mesosomal dorsum usually has sharp borders between dark and pale color while in F. lugubris such spot, if present, has diffused borders.
- Pitch-black or brown large patch on promesonotum (if present) with diffused margins. Frons appearing at low magnification not perfectly matt, with a mild silky shine. Setation of mesosomal dorsum and gastral tergites less dense, especially gaster on dorsal surface without or with only few erected setae . . . . . Formica lugubris
Formica lugubris and Formica pratensis are the only members of the nominative subgenus with distinctly setose occipital margin of head ( Formica polyctena and Formica rufa have no or occasionally 1-3 erected setae in occipital part of head). Formica pratensis is the most setose species with distinctly higher number of erected setae on head and mesosoma than in F. lugubris. Especially gaster setation in F. pratensis is denser than in F. lugubris as Greek populations of F. lugubris have setation of first two gastral tergites often limited to the anterior slope of the first tergite while in F. pratensis entire surface of all tergites is densely setose. Aditionally, in F. pratensis dark spot on mesosomal dorsum usually has sharp borders between dark and pale color while in F. lugubris such spot, if present, has diffused borders.
3
return to couplet #1
- Each segment of mesosoma usually lacking erected setae, in rare cases with up to 5 setae. Ventral side of head without or with a few suberect setae . . . . . Formica polyctena
Formica polyctena and Formica rufa form a group of species without with less than 3 erected setae in occipital part of head. They have also less setae on mesosomal dorsum than both congeners: Formica lugubris and Formica pratensis. Formica polyctena and F. rufa are very similar thus for their identification should be based on numerous nest samples. Generally, F. polyctena is slightly smaller and less setose than F. rufa, usually its mesosoma completely lacking erected setae or in rare cases has up to 5 setae on each segment while in F. rufa most often each segment of mesosoma has at least 6 erected setae (often many more). Also, in F. polyctena ventral side of head usually has no or only few suberect setae while in F. rufa such setae are usually present and rather numerous.
- Each segment of mesosoma with at least 6 erected setae (often many more, only occasionally with 2-3). Ventral side of head with long erect setae . . . . . Formica rufa
Formica rufa and Formica polyctena form a group of species without or with not more 3 erected setae in occipital part of head. They also have lower number of setae on mesosomal dorsum than in both congeners: Formica lugubris and Formica pratensis. They are very similar in difficult to identification without a series of specimens from a nest sample. For comparative characters see remarks under F. polyctena.