Polyrhachis annosa

Introduction

Polyrhachis annosa is an extinct fossil ant species known from a single worker preserved in Late Miocene deposits (approximately 7 to 5 million years old) on Crete, Greece . The fossil measures about 7 to 7.5 mm in total body length, based on a 6.5 mm imprint . It features distinctive lateral petiolar spines, an unarmed pronotum, and propodeal teeth . This species belongs to the genus Polyrhachis, which contains nearly 700 living species spread across the Palaeotropics and Australia . The fossil was found in the Varvara Formation of the Messara Basin, embedded in laminated calcareous mudstones that point to a deep basin environment with anoxic bottom water . This fossil neatly matches the expectations for the genus Polyrhachis by clearly showing lateral petiolar spines, a key trait for the group . While we cannot keep this species because it went extinct millions of years ago, modern Polyrhachis ants are active, diurnal foragers that live in varied habitats like leaf litter, hollow bamboo, and between leaves . Many living species use larval silk to weave nests, and some form massive multi-queen colonies with tens of thousands of workers . If you want to keep a living relative, look for modern spiny ants in this genus.