﻿AbstractThe genusLinepithemawas erected byMayr (1866)for his male-based speciesL.fuscum. In this study a new species is described also based on male morphology,L.paulistanasp. nov., collected in the city of São Paulo, Brazil, which is attributed to thefuscumgroup (Formicidae:Dolichoderinae).Linepithemapaulistanasp. nov.is the only species offuscumgroup present in the eastern part of South America. It is easily distinguishable from the other species of the group because of the presence of a triangular volsellar tooth, which is distally situated between the digitus and the basivolsellar process. By usingSEMand optical microscopy, the external genitalia ofL.paulistanasp. nov.were analyzed and illustrated and some characters and previous interpretations have been re-evaluated in theLinepithemafuscumgroup. The male external genitalia are also comparatively analyzed in three species representative of the threeLinepithemaspecies groups, those offuscum,humile, andneotropicum. The present work confirms that the morphological characters of male ants, especially those of male external genitalia, are effective for the identification of genera or species. Given the discrete morphological differences between the external genitalia of thefuscumgroup and the other species of this genus, a re-evaluation of the generic status ofLinepithemais suggested.