[quote="tail__"]Please give EXACT length in milimeters, when asking for identification. And don't trust your eyes, always have a ruler with you

I also suppose it's Tapinoma. Look very close at the worker's head (preferably dead specimen, unless you are able to convince the worker to stand still - maybe with some sweet bait). If you see the ocelli (three little eyes on forehead), they are Formicinae. They are, however, very hard to spot when the ant is small and coloured black, like Lasius niger, so use strong magnifying glass. Dolichoderinae workers don't have ocelli, only queens and males.
-I can´t understand this... Ocelli(infra-eyes for searching sun´s aspect and strong of photons) have also Ponerinae ants... For example species of genus Ponera and Diacamma have ocelli...
Formicinae, for example some Camponotus workers don´t have ocelli, I think there´s no specie of Camponotus in central Europe, which´s workers have these smaller eyes.... But Formica hardly have, they need these eyes, cause workers are traveling long ways in the outside area of their colony...
Also their pigmentation and chitin(I mean ,,Tapinoma" on photos) isn´t like L. niger´s, they are more like L. fuliginosus, but just by the way of chitin´s outlook....