Pheidole praehistorica sp. nov., a new addition to spiny ants of the genus Pheidole Westwood, 1839 (Formicidae, Myrmicinae) from Oligo–Miocene Mexican amber

Abstract

A fossil species of ant, Pheidole praehistorica sp. nov. (Hymenoptera, Formicidae, Myrmicinae), is described and illustrated from the late Oligocene and early Miocene amber-bearing beds of Mexico. The type material comprises five amber inclusions from the Simojovel site in Chiapas. Pheidole praehistorica is recognized by having compound eyes positioned mesad on the head and protruded laterally from the head’s margins; pronotum long, forming a neck, with a pair of spines directed dorsolaterally; mesonotal groove deep forming a more or less U-shape concavity in lateral view; dorsal and declivitous faces of the propodeum well differentiated, comprising an approximately 90 degrees angle; propodeum with a pair of long spines; peduncle of the petiole long, as long as the spines of the propodeum. A phylogenetic analysis was also performed using Formica integroides, Camponotus chartifex, Dolichoderus spurius, Cephalotes minutus and Atta mexicana to assess the relationships of P. praehistorica with its fossil spiny congeners from Dominican amber and closely related extant species. The results show close morphological and phylogenetic affinities between the fossil ant P. praehistorica with P. primigenia and P. tethepa from Dominican amber, which may suggest that the shared spinescence character in Pheidole has a probable New World ancestry. The new record of P. praehistorica in the Oligo–Miocene strata of southernmost North America provides further evidence for the ancient distribution of spiny ants of the genus Pheidole in the New World.