Gallaecimonas is a recently described genus of bacteria. The first described species of this genus was Gallaecimonas pentaromativorans gen. nov., sp. nov. isolated by Rodríguez Blanco et al. in 2010 from intertidal sediments of the ria of Corcubión (Galicia, Spain). It is a Gram-negative, rod-shaped, halotolerant bacterium in the class Gammaproteobacteria. It can degrade high molecular mass polycyclic aromatic hydrocarbons of 4 and 5 rings. The 16S rRNA gene sequences of the type strain CEE_131(T) proved to be distantly related to those of Rheinheimera and Serratia. Its G+C content was 41.7 mol%.