The genus Pheidole is currently considered to be the most diverse genus of Ants, with 1160 living and six fossil species. Although global in distribution, the genus is at its most diverse in the Neotropics, and is presumed to have originated in this region. This is supported by the locations from which the known fossils in the genus have been recovered, with the oldest known species coming from the Eocene of Colorado, and other fossils known from the Miocene of the Dominican Republic (three species), and the Oligo-Miocene of Chiapas State, Mexico (2 species).
In a paper published in the European Journal of Taxonomy on 25 October 2024, Fernando Varela-Hernández & Franciso Riquelme of the Laboratorio de Sistemática Molecular at the Universidad Autónoma del Estado de Morelos, describe a third species of Pheidole from Chiapas Amber.
Chiapas Amber comes from the Simojovel, Totolapa, and Estrella de Belén localities in the Chiapas Highlands of southern Mexico, with the Simojovel site being the main centre of commercial amber extraction. The amber comes from a series of limestone, sandstone, siltstone, shale, and lignite beds of Late Oligocene to Early Miocene age, referred to as either the Simojovel Formation or the La Quinta Formation. The amber here is thought to have derived from a type of Leguminous tree of the genus Hymenaea; resin-producing trees belonging to this genus are also thought to have been responsible for Dominican Amber, which is of approximately the same age as Chiapas Amber, and are still found today across the Neotropics.
The new species is named Pheidole praehistorica, where 'praehistorica' means 'prehistoric' in reference to the nature of the material from which it is described, five fossil Ants trapped within a single species of amber.
Pheidole praehistorica is smaller than other species from Chiapas Amber, an average length of 2.3 mm, and has shorter pronotal spines (spines on the forward part of the thorax, immediately behind the head) and straight propodeal spines (spines on the rear part of the thorax, immediately before the abdomen.
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