Description of a new twig-nesting species of the Crematogaster quadriruga group (Hymenoptera: Formicidae) from Vietnam, with an updated key

A new species of the ant genus Crematogaster is described from the worker and queen castes. Crematogaster epispina sp. nov., belonging to the Crematogaster quadriruga group, is discovered in a dead twig on a tree in Vietnam. Crematogaster epispina sp. nov. is distinguished from other members by having the propodeal spines curving upward and propodeal spiracles touching the metapleural gland bulla. An updated key to the species of the C. quadriruga group is proposed.