Odontomachus spinifer

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Odontomachus spinifer is an extinct ant from the subfamily Ponerinae, known from a single fossil in Dominican amber on the island of Hispaniola. The amber came from the extinct tree Hymenaea protera and was found in the Cordillera Septentrional mountains of northern Dominican Republic. The amber’s age is uncertain: it is at least from the Burdigalian stage of the Miocene based on associated microfossils, but could be as old as the Middle Eocene because the rock that hosts the amber is a secondary deposit.

The holotype, Do-2215, is part of the State Museum of Natural History Stuttgart collections in Germany. It was described in 1994 by entomologist Maria L. De Andrade. The species name spinifer means “bearing a spine,” referring to a large spine on the top of the ant’s petiole.

Based on the head, O. spinifer is placed in the O. haematodus group, closely related to O. affinis, O. mayi, and O. panamensis. Modern Hispaniola ants in the genus Odontomachus, O. bauri and O. insularis, are not closely related to spinifer.

The fossil worker is about 11.1 mm long and has a yellowish‑red to reddish‑brown, shiny exoskeleton with tiny punctuations on the head, mandibles, petiole node, and gaster. The frons and some parts of the body show striation. The head is large and rectangular, about two‑thirds as long as it is wide. The mandibles are nearly as long as the head and have twelve teeth, with three small teeth at the tip. The antennae have very long scapes, and the first funicular segment is longer than the second. The thorax is elongated, the petiole is slender, and the gaster is bell‑shaped where it connects to the petiole; the sting is partly retracted. A distinctive feature is a large backward‑curving spine on the top of the petiole, longer than the petiole’s width.