Psychroserpens luteolus sp. nov., isolated from Gelidium, reclassification of Ichthyenterobacterium magnum as Psychroserpens magnus comb. nov., Flavihalobacter algicola as Psychroserpens algicola comb. nov., Arcticiflavibacter luteus as Psychroserpens luteus comb. nov.

A Gram-stain-negative, motile by gliding, catalase positive, facultative anaerobic strain, designated strain XSD401T, was isolated from an unidentified Gelidium species of Xiaoshi Island, Shandong Province, China. The 16S rRNA gene sequence comparisons indicated strain XSD401T had a sequence similarity of 96.9% with Psychroserpens damuponensis KCTC 23539T and 96.3% with Psychroserpens burtonensis DSM 12212T. The G + C content of the genomic DNA was 33.9%. The ANI values between strain XSD401T and P. damuponensis KCTC 23539T, P. burtonensis DSM 12212T, were 76.9% and 76.9%, respectively. The dDDH values between strain XSD401T and P. damuponensis KCTC 23539T, P. burtonensis DSM 12212T, were 20.4% and 20.3%, respectively. The AAI values and POCP values of these 8 species were all over 72% and 50%. Combined with the results of comparative genomic analysis, Ichthyenterobacterium magnum, Flavihalobacter algicola and Arcticiflavibacter luteus were reclassified into Psychroserpens. Furthermore, the differences in morphology, physiology and genotype from the previously described taxa support the classification of strain XSD401T as a representative of the genus Psychroserpens, for which the name Psychroserpens luteolus sp. nov. is proposed. The type strain is XSD401T (= MCCC 1H00396T = KCTC 72684T = JCM 33931T).