Name: Curtobacterium aurantiacum Osdaghi et al. 2025

Category: Species

Proposed as: sp. nov.

Etymology: au.ran.ti’a.cum. N.L. neut. adj. aurantiacum, orange-pigmented, the epithet refers to Corynebacterium flaccumfaciens var. aurantiacum the orange-pigmented variant of Corynebacterium flaccumfaciens causing wilt disease on dry beans

Gender: neuter

Type strain: 50R; CFBP 8819; ICMP 22071

Conduct genome-based taxonomy at

Effective publication: Osdaghi E, Taghavi SM, Hamidizade M, Kariminejhad M, Fazliarab A, Hajian Maleki H, Baeyen S, Taghouti G, Jacques MA, Van Vaerenbergh J, et al. Multiphasic investigations imply transfer of orange-/red-pigmented strains of the bean pathogen Curtobacterium flaccumfaciens pv. flaccumfaciens to a new species as C. aurantiacum sp. nov., elevation of the poinsettia pathogen C. flaccumfaciens pv. poinsettiae to the species level as C. Poinsettiae sp. nov., and synonymy of C. albidum with C. citreum. Syst Appl Microbiol 2024; 47:126489.

IJSEM list: Oren A, Göker M. Validation list no. 222. List of new names and new combinations previously effectively, but not validly, published. Int J Syst Evol Microbiol 2025; 75:6640.

Nomenclatural status: validly published under the ICNP

Taxonomic status: synonym (taxonomically suspended)

Correct name: Curtobacterium flaccumfaciens (Hedges 1922) Collins and Jones 1984

• Synonyms:

  • Name	Kind
    "Bacterium flaccumfaciens" Hedges 1922	heterotypic synonym, not validly published, basonym of name in Approved Lists
    Corynebacterium flaccumfaciens (Hedges 1922) Dowson 1942 (Approved Lists 1980)	heterotypic synonym, validly published under the ICNP
    Corynebacterium oortii Saaltink and Maas Geesteranus 1969 (Approved Lists 1980)	heterotypic synonym, validly published under the ICNP
    Corynebacterium betae Keyworth et al. 1956 (Approved Lists 1980)	heterotypic synonym, validly published under the ICNP
    Corynebacterium flaccumfaciens subsp. betae (Keyworth et al. 1956) Carlson and Vidaver 1982	heterotypic synonym, validly published under the ICNP, distinct rank
    Corynebacterium flaccumfaciens subsp. oortii (Saaltink and Maas Geesteranus 1969) Carlson and Vidaver 1982	heterotypic synonym, validly published under the ICNP, distinct rank
    Corynebacterium flaccumfaciens subsp. poinsettiae (Starr and Pirone 1942) Carlson and Vidaver 1982	heterotypic synonym, validly published under the ICNP, distinct rank
    "Curtobacterium poinsettiae" (Starr and Pirone 1942) Osdaghi et al. 2024	heterotypic synonym, not validly published
    Curtobacterium flaccumfaciens (Hedges 1922) Collins and Jones 1984	heterotypic synonym, validly published under the ICNP
    "Phytomonas poinsettiae" Starr and Pirone 1942	heterotypic synonym, not validly published, basonym of name in Approved Lists
    Corynebacterium poinsettiae (Starr and Pirone 1942) Burkholder 1948 (Approved Lists 1980)	heterotypic synonym, validly published under the ICNP

• Notes:
  • ⏲ According to Committee (2025), this species is a later heterotypic synonym of "Bacterium flaccumfaciens" Hedges 1922. Publication: Committee AH. Mitigating changes in prokaryotic nomenclature: Definitions and Workflow. Zenodo 2025; 2025:15320329.
  • ⏲ According to Committee (2025), this species is a later heterotypic synonym of Corynebacterium flaccumfaciens (Hedges 1922) Dowson 1942 (Approved Lists 1980). Publication: Committee AH. Mitigating changes in prokaryotic nomenclature: Definitions and Workflow. Zenodo 2025; 2025:15320329.
  • ⏲ According to Committee (2025), this species is a later heterotypic synonym of Curtobacterium flaccumfaciens (Hedges 1922) Collins and Jones 1984. Publication: Committee AH. Mitigating changes in prokaryotic nomenclature: Definitions and Workflow. Zenodo 2025; 2025:15320329.
  • 😢 The terminology used by the authors is in line with many other taxonomic studies and does not negatively affect their main results; some improvements may nevertheless be possible. The phrase "valid name" is misleading. Whether taxa can have "members" is debatable. See the LPSN phylogeny page for details. Publication: Göker M. What can genome analysis offer for bacteria? In: Bridge P, Smith D, Stackebrandt E (eds), Trends in the systematics of bacteria and fungi, CAB International, Wallingford, 2021, p. 255-281.
  • ❗ Curtobacterium aurantiacum is the correct name instead if this species is regarded as a separate species (i.e., if its nomenclatural type is not assigned to another species whose name is validly published, legitimate and not rejected and has priority) within a separate genus Curtobacterium.
  • 🧬 The phylogenomic assignment score of this taxon is 0.18017 (N = 56).
  • 🎓 Name mentioned 0 times in PubMed until 2025-04-08.
  • 🪓 Organisms assigned to this species have previously been classified as Curtobacterium flaccumfaciens (Hedges 1922) Collins and Jones 1984. Publication: Collins MD, Jones D. Reclassification of Corynebacterium flaccumfaciens, Corynebacterium betae, Corynebacterium oortii and Corynebacterium poinsettiae in the genus Curtobacterium, as Curtobacterium flaccumfaciens comb. nov. J. Gen. Microbiol. 1983; 129:3545-3548. Anonymous. Validation list no. 14. Validation of publication of new names and new combinations previously effectively published outside the IJSB. Int J Syst Bacteriol 1984; 34:270-271.
  • 😴 This name is on the List of Recommended Names for bacteria of medical importance (LoRN) as a synonym of the name to be applied to this species. The name is on LoRN because of the recorded risk group of other species in the genus. This name is taxonomically suspended (and therefore not recommended for medical use for now) in favour of Curtobacterium flaccumfaciens (Hedges 1922) Collins and Jones 1984. Publication: Collins MD, Jones D. Reclassification of Corynebacterium flaccumfaciens, Corynebacterium betae, Corynebacterium oortii and Corynebacterium poinsettiae in the genus Curtobacterium, as Curtobacterium flaccumfaciens comb. nov. J. Gen. Microbiol. 1983; 129:3545-3548. Anonymous. Validation list no. 14. Validation of publication of new names and new combinations previously effectively published outside the IJSB. Int J Syst Bacteriol 1984; 34:270-271.

Parent taxon: Curtobacterium Yamada and Komagata 1972 (Approved Lists 1980)

Assigned by: Osdaghi E, Taghavi SM, Hamidizade M, Kariminejhad M, Fazliarab A, Hajian Maleki H, Baeyen S, Taghouti G, Jacques MA, Van Vaerenbergh J, et al. Multiphasic investigations imply transfer of orange-/red-pigmented strains of the bean pathogen Curtobacterium flaccumfaciens pv. flaccumfaciens to a new species as C. aurantiacum sp. nov., elevation of the poinsettia pathogen C. flaccumfaciens pv. poinsettiae to the species level as C. Poinsettiae sp. nov., and synonymy of C. albidum with C. citreum. Syst Appl Microbiol 2024; 47:126489.

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Record number: 64707