A new genus and species of ant from Guatemala (Hymenoptera: Formicidae).

The species described below possesses such unusual characters that I have assigned it to a new genus, Perissomyrmex, the name meaning" strange ant. ' Though definitely belonging to the sub family Myrmicinwe, its exact tribal placement is questionable. This is especially true since no winged forms are available for study. Even though these forms are lacking, I am provisionally placing the species in the tribe Myrmecinini. The most outstanding characters of the new genus are: The 9-segmented antenna with a more or less distinct 3-segmented club; median region of the clypeus with denticulate anterior border; lateral border of the clypeus forming a trenchant ridge in front of the antennal fossa; frontal carina poorly developed, not lobed, thus exposing base of scape and fossa; mandible elon gate, with 3-toothed masticatory border and another tooth on the superior border; promesonotal suture obsolescent or absent, meso epinotal impression well developed; epinotum with a pair of spines; anterior tibia with well developed, pectinate spur, each middle and posterior tibia without spurs; petiole and postpetiole nodiform, the former also pedunculate. Ants of this new genus resemble those of Pristomyrmex, but the resemblance is more superficial than real. There is a difference in the number of antennal segments, presence or absence of tibial spurs, development of frontal carinae and other characters; furthermore, no Pristomyrmex is known to occur in the Americas, the genus being native to Indo-China, Japan, Malaysia, New Guinea and Australia. Perissomyrmex may be an ancient genus whose taxonomic position and affinities cannot be determined until more specimens are available for study. WORKER.-Small, apparently monomorphic. Head large; pos