Description of Tateyamaria algicola sp. nov. and Tateyamaria rhodophyticola sp. nov., Isolated from Marine Algae.

Two aerobic, non-motile, Gram-stain-negative strains, designated SN3-11ᵀ and SN6-1ᵀ, were isolated from marine algae. Both strains were oxidase- and catalase-positive, with rod-shaped morphology. Strain SN3-11ᵀ grew optimally at 25 ℃, pH 7.0-8.0, and 2.0-5.0% (w/v) NaCl, while strain SN6-1ᵀ showed optimal growth at 25 ℃, pH 8.0, and 2.0-3.0% NaCl. Both strains contained ubiquinone-10 as the sole respiratory quinone, and their major fatty acids were summed feature 8 (C_18:1 ω7c and/or C_18:1 ω6c), C_16:0, and C_19:0 cyclo ω8c. Phosphatidylcholine and phosphatidylglycerol were dominant polar lipids, with diphosphatidylglycerol additionally present in SN3-11ᵀ. Strains SN3-11ᵀ and SN6-1ᵀ had genome sizes of 4,762 Kb and 4,157 Kb with G + C contents of 61.3% and 62.0%, respectively. They shared 96.9% 16S rRNA gene sequence similarity, 77.0% average nucleotide identity (ANI), and 20.2% digital DNA-DNA hybridization (dDDH), supporting their classification as distinct species. Their closest relative, Tateyamaria armeniaca KMU-156ᵀ, exhibited 16S rRNA gene sequence similarities of 98.6% to SN3-11ᵀ and 97.7% to SN6-1ᵀ. Phylogenetic trees based on 16S rRNA and whole-genome sequences placed both strains in distinct lineages within Tateyamaria. ANI and dDDH values between the two isolates and other Tateyamaria species were < 78.5% and < 21.0%, respectively. Strains SN3-11ᵀ and SN6-1ᵀ harbored genes encoding diverse carbohydrate-active enzymes and biosynthetic pathways for lycopene, pantothenate, and riboflavin, suggesting potential symbiotic roles with algal hosts. Based on phenotypic, chemotaxonomic, and genomic characteristics, SN3-11ᵀ and SN6-1ᵀ represent two novel species, Tateyamaria algicola sp. nov. (SN3-11ᵀ = KACC 23689ᵀ = JCM 36649ᵀ) and Tateyamaria rhodophyticola sp. nov. (SN6-1ᵀ = KACC 23127ᵀ = JCM 35962ᵀ).