Acanthognathus poinari is an extinct species of ant in the subfamily Myrmicinae known from a single possibly Miocene[1] fossil found on Hispaniola.

[2] Acanthognathus poinari is known from a solitary fossil insect which, along with six dipteran and a leaf section, is an inclusion in a transparent chunk of Dominican amber.

The specimens were collected from an undetermined amber mine in fossil bearing rocks of the Cordillera Septentrional mountains, northern Dominican Republic.

The fossil was first studied by entomologists Cesare Baroni Urbani and Maria L. De Andrade of the University of Basle with their 1994 type description of the new species being published in the journal Transactions of the American Entomological Society.

The specific epithet poinari is a patronym honoring George Poinar for his enthusiasm for amber which interested the authors into study of the specimens.