David Ruiz Arahal

Opinion 133 addresses the unusual situation of two genus names that are homonyms and are also considered heterotypic synonyms. Furthermore, it clarifies the meaning of the term ‘homonym’ in the International Code of Nomenclature of Prokaryotes, as well as the implications of the absence of the term ‘isonym’ from that code. Isonyms are homotypic synonyms with the same spelling and as such are adequately regulated by the code. The Judicial Commission agrees that the names Methylacidiphilum caldifontis Awala et al . 2023, Methylacidiphilum Awala et al . 2023, Methylacidiphilaceae Awala et al . 2023 and Methylacidiphilales Awala et al . 2023 are illegitimate. The possible actions to resolve this illegitimacy are outlined. The request to conserve Methylacidiphilum Awala et al . 2023 over Methylacidiphilum Ratnadevi et al . 2023 is not granted. However, Methylacidiphilaceae Awala et al . 2023 and Methylacidiphilales Awala et al . 2023 are conserved with Methylacidiphilum Ratnadevi et al . 2023 as the type genus, thereby rendering them legitimate. Opinion 134 addresses two distinct enquiries arising from the same Request for an Opinion. The Judicial Commission confirms that the priority between Yokenella regensburgei Kosako et al . 1985 and its heterotypic synonym Koserella trabulsii Hickman-Brenner et al . 1985 may at present be unresolved. Considering previous statements by the Judicial Commission, the differences in the amount of usage between the two names and their medical relevance, the request is granted. The name Yokenella Kosako et al . 1985 is conserved over Koserella Hickman-Brenner et al . 1985, as is the epithet in Yokenella regensburgei Kosako et al . 1985 over the epithet in Koserella trabulsii Hickman-Brenner et al . 1985. The Judicial Commission also confirms that the epithet in Proteus inconstans (Ornstein 1920) Shaw and Clarke 1955 (Approved Lists 1980) has priority over the one in its homotypic synonym Providencia alcalifaciens (de Salles Gomes 1944) Ewing 1962 (Approved Lists 1980). However, it is doubtful whether this renders Providencia Ewing 1962 (Approved Lists 1980) illegitimate. There are other reasons to conserve the epithet in Providencia alcalifaciens (de Salles Gomes 1944) Ewing 1962 (Approved Lists 1980) over that in Proteus inconstans (Ornstein 1920) Shaw and Clarke 1955 (Approved Lists 1980), and this request is also granted.

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The members of the International Committee on Systematics of Prokaryotes (ICSP) have recently voted on a proposed revision of its statutes. We here present the outcome of the vote and the text of the revised statutes, as approved by the ICSP.

Opinion 132 deals with a Request for an Opinion asking the Judicial Commission to assess the nomenclatural status of Skermania piniformis (Blackall et al. 1989) Chun et al. 1997, a new combination affected by an unusual change in the epithet of its basonym, Nocardia pinensis Blackall et al. 1989. This is done by re-evaluating Opinion 85, which sets a precedent. The reasons and consequences of this earlier Opinion are explained in detail, and corresponding guidelines for orthographic corrections are given, along with further guidance derived from more recently published Judicial Opinions. The request to change the epithet to Skermania pinensis corrig. (Blackall et al. 1989) Chun et al. 1997 is granted, and it is also emphasized that this does not affect the legitimacy or the date of valid publication of the names involved. The Judicial Commission also grants the third request made in the same article and rules that, according to Rule 54 of the International Code of Nomenclature of Prokaryotes (ICNP), it is not necessary, and even unwise, to propose two names for the same taxon in the same study to replace an illegitimate name.

Opinion 131 addresses a Request for an Opinion asking the Judicial Commission to conserve the genus name Proteus Hauser 1885 (Approved Lists 1980) over its earlier homonym, the protozoan genus name Proteus Müller 1786. The Judicial Commission agrees that the later homonym is illegitimate and that the replacement of the prokaryotic name Proteus would be undesirable. It is also concluded that Proteus Müller 1786 is an objectively invalid name under the International Code of Zoological Nomenclature. Judicial Opinions 9, 12 and 130 serve as precedents for the conservation of Proteus Hauser 1885 (Approved Lists 1980) over Proteus Müller 1786. This action is taken here and makes the prokaryotic name Proteus legitimate.

The editorial Board of the International Code of Nomenclature of Prokaryotes (ICNP) – the Prokaryotic Code – has compiled already ratified proposed emendations of the ICNP, together with additional editorial changes and clarifications. These were implemented in a draft 2025 revision of the Prokaryotic Code. To comply with Articles 13(b)(4) and 4(d) of the statutes of the International Committee on Systematics of Prokaryotes (ICSP), a public discussion of the document will start on 1 January (or later if required) 2025, to last for 6 months. Here, we present the basis for the revision and the procedure for the discussion. The discussion will be followed by the balloting of the ICSP members.

The purpose of this study is to better characterize and complete the classification of two bacterial strains, CECT 9275^T and CECT 9623^T, isolated from drinking water systems and affiliated to the genus Dyadobacter by partial 16S rRNA gene sequence comparison. Hence, we report here the phenotypic, genomic and phylogenetic characterization performed on these strains. Both strains grow on R2A agar forming mucous, bright yellow colonies, developing at 26 °C in 48 h. They produce flexirubin and are oxidase and catalase positive, mesophilic and non-halophilic. The cells of strain CECT 9275^T are curved rods mainly associated in pairs, forming nearly closed rings or resembling the shape of the number three, to long spirals resembling a corkscrew. Its draft genome has an estimated size of 7.23 Mbp (G+C content 45.4%). Strain CECT 9623^T appeared on wet mounts as straight rods, mostly in pairs, sometimes forming long filaments (up to 20 µm). Its draft genome is shorter, with an estimated size of 6.45 Mbp (G+C content is 46.1%). Overall genome relatedness indexes clearly define them as separate organisms, so based on all the data collected, we propose the species Dyadobacter helix sp. nov. with type strain AB1^T (=CECT 9275^T=LMG 32341^T) and Dyadobacter linearis sp. nov. with type strain AB67^T (=CECT 9623^T=LMG 32342^T).

Opinion 130 deals with a Request for an Opinion asking the Judicial Commission to clarify whether the genus name Rhodococcus Zopf 1891 (Approved Lists 1980) is illegitimate. The Request is approved and an answer is given. The name Rhodococcus Zopf 1891 (Approved Lists 1980) is illegitimate because it is a later homonym of the validly published cyanobacterial name Rhodococcus Hansgirg 1884. The Judicial Commission also clarifies that it has the means to resolve such cases by conserving a name over an earlier homonym. It is concluded that the name Rhodococcus Zopf 1891 (Approved Lists 1980) is significantly more important than the name Rhodococcus Hansgirg 1884 and therefore the former is conserved over the latter. This makes the name Rhodococcus Zopf 1891 (Approved Lists 1980) legitimate.

Prokaryotes dominate global oceans and shape biogeochemical cycles, yet most taxa remain uncultured and uncharacterized as of today. Here we present the characterization of 26 novel marine bacterial strains from a large isolate collection obtained from Blanes Bay (NW Mediterranean) microcosm experiments made in the four seasons. Morphological, cultural, biochemical, physiological, nutritional, genomic, and phylogenomic analyses were used to characterize and phylogenetically place the novel isolates. The strains represent 23 novel bacterial species and six novel genera: three novel species pertaining to class Alphaproteobacteria (families Rhodobacteraceae and Sphingomonadaceae), six novel species and three new genera from class Gammaproteobacteria (families Algiphilaceae, Salinispheraceae, and Alteromonadaceae), 13 novel species and three novel genera from class Bacteroidia (family Flavobacteriaceae), and one new species from class Rhodothermia (family Rubricoccaceae). The bacteria described here have potentially relevant roles in the cycles of carbon (e.g., carbon fixation or energy production via proteorhodopsin), nitrogen (e.g., denitrification or use of urea), sulfur (oxidation of sulfur compounds), phosphorus (acquisition and use of different forms of phosphorus and remodeling of membrane phospholipids), and hydrogen (oxidation of hydrogen to obtain energy). We mapped the genomes of the presented strains to the Tara Oceans metagenomes to reveal that these strains were globally distributed, with those of the family Flavobacteriaceae being the most widespread and abundant, while Rhodothermia being the rarest and most localized. While molecular-only approaches are also important, our study stresses the importance of culturing as a powerful tool to further understand the functioning of marine bacterial communities.

The International Committee on Systematics of Prokaryotes serves to administer the rules of prokaryotic nomenclature via the International Code of Nomenclature of Prokaryotes, ensures the publication of the International Journal of Systematic and Evolutionary Microbiology, and works to represent the interests of the microbiological disciplines regarding prokaryotic nomenclature. The functions and mechanisms of operation of the International Committee on Systematics of Prokaryotes (ICSP) are defined in its Statutes, which were last revised in 2019. As members of the 2020–2023 and the 2023–2026 ICSP Executive Board and the Judicial Commission, we propose here some further revisions to help improve the clarity and functionality of the Statutes.