Anbarrhacus is an extinct genus of millipede in the family Platyrhacidae known from a fossil found in North America.

[1][2] Anbarrhacus adamantis was described from a solitary fossil, which is preserved as an inclusion in a transparent chunk of Mexican amber.

The Guadalupe Victoria site is an outcrop of amber bearing strata belonging to both the Mazantic Shale and Balumtum Sandstone.

[1][2][3] The holotype was first studied by a team of researchers headed by Francisco Riquelme of the Universidad Autónoma del Estado de Morelos with their 2014 type description of the genus and species being published in the natural sciences journal PLOS ONE.

The specific epithet adamantis was coined from the Neo-Latin word adamantus meaning diamond, a reference to the patterning on the tops of the collum and metatergites.