Fulvivirga aurantia sp. nov. and Xanthovirga aplysinae gen. nov., sp. nov., marine bacteria isolated from the sponge Aplysina fistularis, and emended description of the genus Fulvivirga.

Two Gram-stain-negative, strictly aerobic, marine bacteria, designated as strains RKSG066T and RKSG123T, were isolated from a sponge Aplysina fistularis collected at a depth of 15 m off the west coast of San Salvador, The Bahamas. Investigation of nearly full-length 16S rRNA gene and whole genome-based phylogenies revealed that both strains belong to the order Cytophagales within the class Cytophagia and phylum Bacteroidetes. Strain RKSG066T formed a monophyletic clade with described members of the genus Fulvivirga, while strain RKSG123T formed a well-supported paraphyletic branch apart from this and other related genera within the family Flammeovirgaceae. For both RKSG066T and RKSG123T, optimal growth parameters were 30-37 °C, pH 7-8 and 2-3 % (w/v) NaCl; cells were catalase- and oxidase-positive, and flexirubin-type pigments were absent. The predominant fatty acids were iso-C15 : 0, C16 : 0, C18 : 0, iso-C17 : 0 3-OH, C16 : 1 ω5c, iso-C15 : 0 3-OH, C18 : 1 ω9c and iso-C15 : 1 G for RKSG066T, and iso-C17 : 0 3-OH, C16 : 1 ω5c, iso-C15 : 0, C16 : 0 3-OH and summed feature 4 (iso-C17 : 1 I and/or anteiso-C17 : 1 B) for RKSG123T. Menaquinone-7 was the major respiratory quinone for both strains. The DNA G+C contents of RKSG066T and RKSG123T were 39.5 and 36.7 mol%, respectively. On the basis of phylogenetic distinctiveness and polyphasic analysis, the type strain RKSG066T (=TSD-73T=LMG 29870T) is proposed to represent a novel species of the genus Fulvivirga, for which the name Fulvivirga aurantia sp. nov. is proposed. The type strain RKSG123T (=TSD-75T=LMG 30075T) is proposed to represent the type species of a novel genus and species with the proposed name Xanthovirga aplysinae gen. nov., sp. nov. Additionally, the genus Fulvivirga is emended to include strains of orange-pigmented colonies that contain the predominant cellular fatty acids C16 : 0, C18 : 0, C16  :  1 ω5c and C18  :  1 ω9c.