Abstract
Résumé: Two new Nearctic ants of the genus Leptothorax (sensu stricto) are described. One, L. retractus, has a transcontinental range, while the other, L. sphagnicolus, was found until now only in the spruce bogs of the Saguenay–Lac-St-Jean region in Quebec. Their chromosome numbers are, respectively, n = 17–18 and n = 13. Both species exhibit an unusual production of intermorphic females and a boreo-temperate geographic distribution. Available bio-ecological data and their taxonomic position within the genus are discussed.