haloarcula quadrata haloarcula quadrata haloarcula quadrata is a species of archaea discovered in a brine pool in the sinai peninsula of egypt. it was one of the first strains of prokaryotes whose cells show a flat, box-like shape. haloarcula quadrata scientific classification domain: archaea phylum: euryarchaeota class: halobacteria order: halobacteriales family: halobacteriaceae genus: haloarcula species: h. quadrata binomial name haloarcula quadrataoren et al. 1999 they were categorized as haloarcula on the basis of their polar lipid composition. morphology and metabolism the cells move using single or multiple flagella but lack gas vacuoles. species within the genus haloarcula are gram negative and extremely halophilic, and they can use any of several sources of carbon.