An introduced slug, Boettgerilla pallens Simroth, 1912, was found both in the Pedregal de San Angel Ecological Reserve, Ciudad Universitaria, Mexico City and Teopancingo, Puebla. Although this slug is native to Europe, it has been recently recorded from various locations around the world. Through dissection, the diagnostic characters were identified as the spindle shaped swelling along the vas deferens characteristic of the genus, and the elongate shape of the bursa copulatrix typical of this species. In addition, cytochrome oxidase I mtDNA, and 16S and 28S ribosomal RNA genes were sequenced and used in a phylogenetic analysis to confirm its identity.