Abstract

Results of previous multilocus sequence and whole-genome-based analyses have suggested that a homogeneous group of isolates belonging to the genus Tenacibaculum, represented by strain TNO020(T) and associated with skin ulcer development in sea-farmed fish, represents an as-yet-undescribed species. Comparative whole-genome analysis performed in the present study clustered five isolates, including TNO020(T), in a distinct lineage within the genus Tenacibaculum. Phenotypic differences, high intra-cluster average nucleotide identity (ANI) values and low ANI values with other Tenacibaculum species support the proposal of a novel species, for which we propose the name Tenacibaculum piscium sp. nov. with strain TNO020(T) (=CCUG 73833(T)=NCIMB 15240(T)) as the type strain. Further, large-scale genome analyses confirmed the existence of two different phylogenetic lineages within 'T. finnmarkense', a species effectively but not validly published previously. ANI values just above the species delineation threshold of 95-96% confirmed that both lineages belong to the same species. This result was also supported by DNA-DNA hybridization values. Phenotypically, the two conspecific lineages are distinguishable by differences in growth temperature range and ability to degrade l-proline. For the group of isolates already commonly known as 'T. finnmarkense', we propose the name Tenacibaculum finnmarkense sp. nov., with strain TNO006(T) (=CCUG 73831(T)=NCIMB 15238(T)) as the type strain. We further propose the subdivision of T. finnmarkense sp. nov. into two genomovars, T. finnmarkense genomovar finnmarkense with strain TNO006(T) (=CCUG 73831(T)=NCIMB 15238(T)) as the type strain and T. finnmarkense genomovar ulcerans with strain TNO010(T) (=CCUG 73832(T)=NCIMB 15239(T)) as the type strain.