Rights to slightly curved rods (0.4-0.7 x 3-20 microns), non-mobile, with curved shapes, branched, gram-negative, the division is by budding or connections with constriction, the presence of spherical protrusions ends of the cells and pili or laterally terminal, lateral or peripheral. Anaerobic or microaerophilic heterotrophic growth on complex organic substrates (yeast extract, gelatin, glycogen, beef extract, peptone, tryptone) and in the presence of S °, thiosulfate or sulfate as electron acceptors. The time division is 8 h with optimal growth temperature to 85 ° C (60-92 ° C) and a pH optimum of 3.7 to 4.2 (2.3 to 5.9). The content of the DNA is 43 mol% G+ C. They are found in acidic hot springs. A single species, Caldivirga maquilingensis .
