Heterotypic Synonym Research Articles

Reinstatement of Struthanthus venetus (Loranthaceae): an endemic species of central Mexico

Struthanthus Mart. is a challenging genus because the abundance of reproductively incomplete specimens (lacking mature pistillate and staminate flowers and fruit) has inspired the description of many species, resulting in a long list of names to be verified. In addition, the genus currently lacks a monographic treatment. Struthanthus venetus (Kunth) Blume was previously considered a heterotypic synonym of S. interruptus (Kunth) G. Don. However, examination of herbarium specimens and observation of living plants demonstrate that S. venetus is a distinct species distinguishable from S. interruptus. Here, we propose the reinstatement of S. venetus along with a complete description of the species and the designation of an epitype to complement the reproductively incomplete (lacking flowers) and severely fragmented type.

Roseolithon mirabile (Foslie) comb. nov. (Hapalidiales, Corallinophycidae, Rhodophyta) based on DNA sequencing of the Archaeolithothamnion mirabile lectotype

Abstract Lithothamnion mirabile is currently considered a heterotypic synonym of L. muelleri. Three of the 14 specimens and additional fragments comprising the holotype of L. mirabile were selected for DNA sequencing as they best matched the protologue. The three 263-base pair rbcL sequences were distinct from each other, and were classified in the order Hapalidiales, but none were resolved in Lithothamnion. One sequenced specimen belongs in Roseolithon and was selected as the lectotype; thus we propose R. mirabile (Foslie) comb. nov. Another sequenced specimen groups with Phymatolithopsis and the third is well resolved in an undescribed genus of Hapalidiales sister to Boreolithothamnion.

Thioclava arctica sp. nov. and Zhongshania arctica sp. nov., isolated from the surface sediment of the Arctic Ocean and reclassification of Marortus luteolus Yu et al. 2019 as a later heterotypic synonym of Zhongshania marina On et al. 2019.

Two Gram-stain-negative bacterial strains, 15-R06ZXC-3T and R06B22T, were isolated from the surface sediment of the Arctic Ocean. Phylogenetic analyses based on the 16S rRNA gene and genome sequences indicated that strain 15-R06ZXC-3T belongs to the genus Thioclava, while strain R06B22T belongs to the genus Zhongshania. Strain 15-R06ZXC-3T showed the closest relationship to Thioclava indica DT23-4T. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain 15-R06ZXC-3T and all of the type strains of the genus Thioclava ranged from 20.8 to 30.4% and 79.1 to 85.7%, respectively. Strain R06B22T was most closely related to Zhongshania marina DSW25-10T. The dDDH and ANI values between strain R06B22T and all of the type strains of the genus Zhongshania ranged from 18.6 to 20.4% and 77.5 to 79.4%, respectively. These dDDH and ANI values were all below the standard cutoff criteria for the delineation of bacterial species, indicating that the two strains may represent novel species within their respective genera. Furthermore, their phenotypic and chemotaxonomic characteristics also differentiated them from closely related species. Based on the polyphasic analyses, strains 15-R06ZXC-3T and R06B22T separately represent novel species of the genera Thioclava and Zhongshania, for which the names Thioclava arctica sp. nov. (type strain 15-R06ZXC-3T = MCCC 1A07434T= KCTC 8342T) and Zhongshania arctica sp. nov. (type strain R06B22T = MCCC 1A08273T= KCTC 8343T) are proposed. Additionally, phylogenomic analyses showed that the strain Marortus luteolus ZX-21T was clustered with the strain Z. marina DSW25-10T and all other type strains of the genus Zhongshania. Furthermore, the ANI and dDDH values between strains ZX-21T and DSW25-10T were 97.6% and 78.8±2.5%, respectively, strongly indicating that they represented a single species. Therefore, it is proposed that M. luteolus Yu et al. 2019 be recognized as a later heterotypic synonym of Z. marina On et al. 2019.

Phylogenomic analyses of the Listeriaceae family support species reclassification and proposal of a new family and new genera.

The taxonomy of the Listeriaceae family has undergone substantial revisions, expanding the Listeria genus from 6 to 29 species since 2009. However, these classifications have relied on 16S rRNA gene sequences and conventional polyphasic taxonomy, with limited use of genomic approaches. This study aimed to employ genomic tools, including phylogenomics, Overall Genomic Relatedness Indices (OGRIs), and core-genome phylogenomic analyses, to reevaluate the taxonomy of the Listeriaceae family. The analyses involved the construction of phylogenetic and phylogenomic trees based on 16S rRNA gene sequences and core genomes from 34 type strain genomes belonging to Listeriaceae family. OGRIs, which encompass Average Amino acid Identity (AAI), core-proteome AAI (cAAI), and Percentage of Conserved Proteins (POCP), were calculated, and specific threshold values of 70%, 87%, and 72-73% were established, respectively, to delimitate genera in the Listeriaceae family. These newly proposed OGRI thresholds unveiled distinct evolutionary lineages. The outcomes of this taxonomic re-evaluation were: (i): the division of the Listeria genus into an emended Listeria genus regrouping only Listeria senso stricto species; (ii): the remaining Listeria senso lato species were transferred into three newly proposed genera: Murraya gen. nov., Mesolisteria gen. nov., and Paenilisteria gen. nov. within Listeriaceae; (iii): Brochothrix was transferred to the newly proposed family Brochothricaceae fam. nov. within the Caryophanales order; (iiii): Listeria ivanovii subsp. londonensis was elevated to the species level as Listeria londonensis sp. nov.; and (iiiii): Murraya murrayi comb. nov. was reclassified as a later heterotypic synonym of Murraya grayi comb. nov. This taxonomic framework enables more precise identification of pathogenic Listeriaceae species, with significant implications for important areas such as food safety, clinical diagnostics, epidemiology, and public health.

Typification of the names in Armeria (Plumbaginaceae) recorded for Italy

A contribution to the nomenclature of the genus Armeria is presented. Armeria alpina, A. gracilis, A. macropoda, A. plantaginea, Statice nebrodensis, S. plantaginea, and S. pungens, recorded for Italy, are typified here based on specimens deposited at B, G, MA, and NAP, plus an illustration by Allioni. The current application of these names is confirmed in most cases, except for Statice plantaginea, which is shown to be a heterotypic synonym of the Alpine endemic Armeria arenaria subsp. praecox, and not of the western Mediterranean A. alliacea, as previously thought. Accordingly, the latter species is excluded from the Italian flora.

Phylogenomic Analysis Supports the Reclassification of Caldicoprobacter faecalis (Winter et al. 1988) Bouanane-Darenfed et al. (2015) as a Later Heterotypic Synonym of Caldicoprobacter oshimai Yokoyama et al. (2010).

This study employs genome-based methodologies to explore the taxonomic relationship between Caldicoprobacter faecalis DSM 20678T and Caldicoprobacter oshimai DSM 21659T. The genome-based similarity indices calculations consisting of digital DNA-DNA Hybridization (dDDH), Average Amino Aid Identity (AAI), and Average Nucleotide Identity (ANI) between the genomes of these two type strains yielded percentages of 91.2%, 98.9%, and 99.1%, respectively. These values were above the recommended thresholds of 70% (dDDH) and 95-96% (ANI and AAI) for bacterial species delineation, indicating a shared taxonomic position for C. faecalis and C. oshimai. Furthermore, analysis utilizing the 'Bacterial Pan Genome Analysis' (BPGA) pipeline and constructing a Maximum Likelihood core-genes tree using FastTree2 consistently demonstrated the close relationship between C. faecalis DSM 20678T and C. oshimai DSM 21659T, evident from their clustering in the core-genes phylogenomic tree. Based on these comprehensive findings, we propose the reclassification of C. faecalis as a later heterotypic synonym of C. oshimai.

Lectotypification of Ceropegia driophila (Apocynaceae) and proposal of Ceropegia paohsingensis as a heterotypic synonym

This study aims to clarify the long‐standing confusion between Ceropegia paohsingensis and C. driophila and to propose the reclassification of C. paohsingensis as a heterotypic synonym of C. driophila. Additionally, we reconsider the types for C. driophila and present a detailed description of the species.

Polaribacter ponticola sp. nov., isolated from seawater, reclassification of Polaribacter undariae as a later heterotypic synonym of Polaribacter sejongensis, and emended description of Polaribacter sejongensis Kim et al. 2013.

A Gram-stain-negative, yellow-pigmented, and strictly aerobic bacterium, designated as strain MSW5T, was isolated from seawater of the Yellow Sea in South Korea. The cells were non-motile rods exhibiting oxidase- and catalase-positive activities. Growth was observed at 15-25 °C (optimum, 25 °C) and pH 5.0-9.0 (optimum, pH 7.0-8.0) and in the presence of 1.0-5.0% (w/v) NaCl (optimum, 2.0%). Menaquinone-6 was the sole respiratory quinone, and iso-C15 : 0, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), iso-C15 : 0 3-OH, and C15 : 1 ω6c were the major cellular fatty acids. Major polar lipids included phosphatidylethanolamine, two unidentified aminolipids, and three unidentified lipids. Phylogenetic analyses based on 16S rRNA gene sequences and 92 concatenated core protein sequences revealed that strain MSW5T formed a distinct lineage within the genus Polaribacter. The genome of strain MSW5T was 3582 kb in size with a 29.1 mol% G+C content. Strain MSW5T exhibited the highest similarity to Polaribacter atrinae WP25T, with a 97.9% 16S rRNA gene sequence similarity. However, the average nucleotide identity and digital DNA-DNA hybridization values were 79.4 and 23.3%, respectively, indicating that strain MSW5T represents a novel species. Based on its phenotypic, chemotaxonomic, and phylogenetic characteristics, strain MSW5T is proposed to represent a novel species, with the name Polaribacter ponticola sp. nov. The type strain is MSW5T (=KACC 22340T=NBRC 116025T). In addition, whole genome sequence comparisons and phenotypic features suggested that Polaribacter sejongensis and Polaribacter undariae belong to the same species, with P. undariae proposed as a later heterotypic synonym of P. sejongensis. An emended description of Polaribacter sejongensis is also proposed.

Genomic evidence that Ornithinicoccus soli Jiang et al. 2020 is a later heterotypic synonym of Segeticoccus rhizosphaerae Lee and Whang 2020.

The genus Segeticoccus includes only one species with validly published name, Segeticoccus rhizosphaerae. The type strain Segeticoccus rhizosphaerae YJ01T was isolated from soil in Korea, while Ornithinicoccus soli XNB-1T was isolated from soil in China. Both strains share similar phenotypic and chemotaxonomic characteristics, including predominant menaquinone MK-8(H4) and major polar lipids diphosphatidylglycerol and phosphatidylglycerol. Whole genome sequences revealed a DNA G+C content of 70.1 mol% for both strains and 100% similarity in their 16S rRNA gene sequences. Phylogenetic analysis showed they form a distinct cluster separate from other genera. Genomic comparisons showed average nucleotide identity and digital DNA-DNA hybridization values of 99.16 and 94.2%, respectively, indicating they represent a single species. Based on this genomic evidence, Ornithinicoccus soli Jiang et al. 2020 is proposed to be a later heterotypic synonym of Segeticoccus rhizosphaerae Lee and Whang 2020.

Psychrosphaera algicola sp. nov. and Paraglaciecola algarum sp. nov., and reclassification of Pseudoalteromonas elyakovii, Pseudoalteromonas flavipulchra, and Pseudoalteromonas profundi as later heterotypic synonyms of P. distincta, P. maricaloris, and P. gelatinilytica.

Two Gram-negative, obligately aerobic, rod-shaped bacteria, strains G1-22T and G1-23T, were isolated from the phycosphere of a marine brown alga. Both strains exhibited catalase- and oxidase-positive activities. Strain G1-22T displayed optimal growth at 25 °C, pH 8.0, and 2.0-3.0% (w/v) NaCl, while strain G1-23T exhibited optimal growth at 25 °C, pH 8.0, and 4.0% NaCl. Ubiquinone-8 was identified as the sole isoprenoid quinone in both strains. As major fatty acids (> 5%), strain G1-22T contained C16 : 0, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c), C12 : 1 3-OH, and C10 : 0 3-OH, while strain G1-23T contained C16 : 0, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), and C14 : 0. Phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol were major polar lipids in both strains. Strains G1-22T and G1-23T had DNA G+C contents of 40.2 and 38.9 mol%, respectively. Phylogenetic analyses based on 16S rRNA and genome sequences revealed that strains G1-22T and G1-23T formed distinct phylogenetic lineages within the genera Psychrosphaera and Paraglaciecola, respectively. Strain G1-22T showed closest relatedness to Psychrosphaera ytuae MTZ26T with 97.8% 16S rRNA gene sequence similarity, 70.2% average nucleotide identity (ANI), and a 21.5% digital DNA-DNA hybridization (dDDH) value, while strain G1-23T was most closely related to Paraglaciecola aquimarina KCTC 32108T with 95.6% 16S rRNA gene sequence similarity, 74.6% ANI, and a 20.1% dDDH value. Based on phenotypic and molecular characteristics, strains G1-22T and G1-23T are proposed to represent two novel species, namely Psychrosphaera algicola sp. nov. (type strain G1-22T=KACC 22486T=JCM 34971T) and Paraglaciecola algarum sp. nov. (type strain G1-23T=KACC 22490T=JCM 34972T), respectively. Additionally, based on the comparison of whole genome sequences, it is proposed that Pseudoalteromonas elyakovii, Pseudoalteromonas flavipulchra, and Pseudoalteromonas profundi are reclassified as later heterotypic synonyms of Pseudoalteromonas distincta, Pseudoalteromonas maricaloris, and Pseudoalteromonas gelatinilytica, respectively.

Reclassification of Streptomyces violarus (Artamonova and Krassilnikov 1960) Pridham 1970 as a Later Heterotypic Synonym of Streptomyces violaceus (Rossi Doria 1891) Waksman 1953 using a Polyphasic Approach.

The taxonomic relationship between Streptomyces violarus and Streptomyces violaceus was reevaluated using a polyphasic taxonomic approach in this work. Phylogenetic analysis based on 16S rRNA gene sequences indicated that Streptomyces violarus JCM 4534T was closely related to Streptomyces arenae ISP 5293T. However, phylogenetic analysis based on five house-keeping gene (atpD, gyrB, recA, rpoB and trpB) showed that the evolutionary neighbor of Streptomyces violarus JCM 4534T was Streptomyces violaceus CGMCC 4.1456T, suggesting that there was a close genetic relationship between these two strains. The average nucleotide identity and digital DNA-DNA hybridization values between them were 97.0 and 72.9%, respectively, greater than the 96.7 and 70% cut-off points recommended for delineating a Streptomyces species. This result indicated that they belonged to the same genomic species which was also verified by a comprehensive comparison of phenotypic and chemotaxonomic characteristics between Streptomyces violarus JCM 4534T and Streptomyces violaceus CGMCC 4.1456T. According to all these data and the rule of priority in nomenclature, it is proposed the Streptomyces violarus (Artamonova and Krassilnikov 1960) Pridham 1970 is a later heterotypic synonym of Streptomyces violaceus (Rossi Doria 1891) Waksman 1953. In addition, based on dDDH, Streptomyces violaceus and Streptomyces violarus are simultaneously designated as two different subspecies, i.e., Streptomyces violaceus subsp. violaceus and Streptomyces violaceus subsp. violarus.

Genome-based reclassification of Kineococcus aureolus Xu et al. 2017 as a later heterotypic synonym of Kineococcus terrestris Xu et al. 2017.

We aimed to elucidate the relationship between Kineococcus terrestris and Kineococcus aureolus through whole-genome-based analysis. The genome-derived 16S rRNA gene sequences of K. terrestris KCTC 39738T and K. aureolus KCTC 39739T shared a 100% similarity. Phylogenetic trees based on 16S rRNA gene and whole-genome sequences revealed that K. terrestris KCTC 39738T and K. aureolus KCTC 39739T formed a robust clade, indicating a close relationship between them. Genomic comparison showed that the two strains shared 99.1% average nucleotide identity, 92.0% digital DNA-DNA hybridization and 98.9% average amino acid identity values, all of which exceeded the recommended threshold values for species classification. Most phenotypic characteristics between the two species were almost identical. Based on the above evidence, we propose the reclassification of Kineococcus aureolus Xu et al. 2017 as a later heterotypic synonym of Kineococcus terrestris Xu et al. 2017. Since these two species were proposed in the same article, the principle of priority does not apply. Our proposal is supported by the fact that the nomenclatural authorities first described Kineococcus terrestris.

Genome-based reclassification of Williamsia marianensis as a later heterotypic synonym of Williamsia muralis.

The present study used whole-genome data to clarify the taxonomic assignment of two closely related Williamsia species. Genomic information for 10 type strains was available at the time of conducting this analysis. One group of type strains was found to be conspecific, namely Williamsia muralis Kämpfer et al. 1999 and Williamsia marianensis Pathom-aree et al. 2006. The 16S rRNA gene sequences showed 99 % similarity between these type strains. Whole-genome-based comparisons showed that Williamsia muralis DSM 44343T and Williamsia marianensis DSM 44944T shared 98.07 % average nucleotide identity, 98.29 % average amino acid identity and 84.80 % digital DNA-DNA hybridization values. These values exceeded the threshold values for bacterial species delineation. Further, phylogenomic analysis based on the core genomes of the strains under study confirmed that Williamsia muralis DSM 44343T and Williamsia marianensis DSM 44944T formed a monophyletic clade. Based on this evidence, we propose the reclassification of Williamsia marianensis Pathom-aree et al. 2006 as a later heterotypic synonym of Williamsia muralis Kämpfer et al. 1999.

Different species or altitudinal morphotypes? Testing the taxonomic value of Dianthus brachycalyx (Caryophyllaceae)

AbstractDefining species boundaries within plant groups distributed along wide elevational and geographic gradients may lead to unstable taxonomic delimitations using morphological data only. Within the taxonomically challenging genus Dianthus, through an integrative approach we tested the taxonomic value of D. brachycalyx, a putative species endemic to mountain peaks of the central‐southern Apennines, with respect to the widespread central‐Mediterranean D. virgineus. We measured 30 morphological characters in 452 individuals from 25 populations and obtained 3202 single nucleotide polymorphisms using ddRAD‐seq techniques in 394 individuals from 36 populations. For climatic niche comparison, we built a dataset of 348 occurrence points. By comparing morphometric, genetic, and climatic niche data, we showed that D. brachycalyx cannot be considered a distinct species. Morphometric separation between the two species is detectable, but high‐elevation populations of D. virgineus are similar to D. brachycalyx. Genetic analyses revealed that the genetic structure of populations of D. brachycalyx and D. virgineus is mainly shaped by isolation‐by‐distance, irrespective of their taxonomic attribution. The climatic niches of the two species are overlapping, and the niche differences are just due to different availability of climatic conditions in their ranges. Accordingly, multiple lines of evidence do not support a separation of D. brachycalyx from D. virgineus, and the former should be considered a heterotypic synonym of the latter.

Genome-based reclassification of Sphingopyxis lutea Chhetri et al. 2023 as a later heterotypic synonym of Sphingopyxis jiangsuensis Gao et al. 2023.

Sphingopyxis lutea DHUNG17T was compared with Sphingopyxis jiangsuensis XHP0097T to examine the taxonomic relationship between the two type strains. The 16S rRNA gene sequence of S. lutea DHUNG17T shared high similarity (99.9 %) to that of S. jiangsuensis XHP0097T. The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that the two strains formed a tight cluster within the genus Sphingopyxis. The average amino acid identity, average nucleotide identity and digital DNA-DNA hybridization values between S. lutea DHUNG17T and S. jiangsuensis XHP0097T were below 99.0, 99.1 and 92.2±1.7 %, respectively, all of which were greater than the species delineation threshold for AAI (95.5 %), ANI (95-96 %) and dDDH (70 %), strongly indicating that the two strains represented a single species. Based on the combined phylogenetic, genomic and phenotypic characterization presented here, we propose Sphingopyxis lutea as a later heterotypic synonym of Sphingopyxis jiangsuensis.

Nomenclature and typification of plant names related to Centaureaaplolepa and C.leucophaea (Asteraceae) from Italy and France.

Centaureaaplolepa Moretti and C.leucophaea Jord. (Asteraceae) are endemic to the central-western Mediterranean and include, respectively, ten and six subspecies, mostly occurring in north-western Italy and south-eastern France. As part of an ongoing systematic study on CentaureaL.sect.Centaurea from the central Mediterranean, 17 nomenclatural types (13 lectotypes, three neotypes and one epitype) are designated to fix the application of all names of the taxa described for France and Italy and related to C.aplolepa and C.leucophaea. In addition, previous typifications are critically revised and discussed. Centaureaaplolepasubsp.maremmana (Fiori) Dostál and C.litigiosa (Fiori) Arrigoni, two currently accepted taxa endemic to Tuscany (central Italy), are respectively considered here as heterotypic synonyms of C.aplolepasubsp.carueliana (Micheletti) Dostál and C.aplolepasubsp.cosana (Fiori) Dostál. Finally, C.aplolepasubsp.gallinariae (Briq. & Cavill.) Dostál, a currently accepted subspecies narrowly endemic to the Gallinara island (Liguria, northern Italy), is considered here as a heterotypic synonym of C.leucophaeasubsp.brunnescens (Briq.) Dostál.

Survival Strategy, Metabolic Potential and Taxonomic Reframe of Kocuria polaris

Antarctica is renowned as the most inhospitable environment where microorganisms are thriving in the frontiers of life. In the past few years, many novel bacterial species have been reported from the Antarctic environment. During taxonomic re-evaluation of novel bacterial species from Antarctica, it was noticed that Kocuria polaris shared high 16S rRNA gene sequence similarity with Kocuria rosea. In the present study, the taxonomic position, metabolic potentials, and stress survival strategy of K. polaris were evaluated through genome analysis. K. polaris encodes genes for glycolysis, citrate cycle, pentose phosphate pathway, dissimilatory nitrate reduction, assimilatory sulfate reduction, etc. In addition, K. polaris also encodes genes for cold and salt stress. The 16S rRNA gene sequence extracted from K. polaris and K. rosea genomes showed 99.7% similarity. In the phylogenomic tree, K. polaris and K. rosea clustered together. The average nucleotide identity and digital DNA–DNA hybridization values between K. polaris and K. rosea exceeded the threshold (95-96% for ANI and 70% for dDDH) value for distinguishing species, showing that they are similar species. The present study shed light on K. polaris survival strategy in extreme conditions. We further propose to reclassify Kocuria polaris as a later heterotypic synonym of Kocuria rosea.

Lacrimispora brassicae sp. nov. isolated from fermented cabbage, and proposal of Clostridium indicum Gundawar et al. 2019 and Clostridium methoxybenzovorans Mechichi et al. 1999 as heterotypic synonyms of Lacrimispora amygdalina (Parshina et al. 2003) Haas and Blanchard 2020 and Lacrimispora indolis (McClung and McCoy 1957) Haas and Blanchard 2020, respectively.

A Gram-stain-negative, endospore-forming, rod-shaped, indole-producing bacterial strain, designated YZC6T, was isolated from fermented cabbage. Strain YZC6T grew at 10-37 °C, pH 5.5-8.5, and with up to 2 % (w/v) NaCl. The major cellular fatty acids were C16 : 0 and C18 : 1 cis 11 dimethyl acetal. Phylogenetic analysis of the 16S rRNA gene revealed that strain YZC6T belonged to the genus Lacrimispora and was closely related to Lacrimispora aerotolerans DSM 5434T (98.3 % sequence similarity), Lacrimispora saccharolytica WM1T (98.1 %), and Lacrimispora algidixylanolytica SPL73T (98.1 %). The average nucleotide identity based on blast (below 87.8 %) and digital DNA-DNA hybridization (below 36.1 %) values between the novel isolate and its corresponding relatives showed that strain YZC6T could be readily distinguished from its closely related species. Based on genotypic, phenotypic, and chemotaxonomic data, a novel Lacrimispora species, Lacrimispora brassicae sp. nov., was proposed, with YZC6T as the type strain (=MAFF 212518T=JCM 32810T=DSM 112100T). This study also proposed Clostridium indicum Gundawar et al. 2019 as a later heterotypic synonym of Lacrimispora amygdalina (Parshina et al. 2003) Haas and Blanchard 2020 and Clostridium methoxybenzovorans Mechichi et al. 1999 as a later heterotypic synonym of Lacrimispora indolis (McClung and McCpy 1957) Haas and Blanchard 2020.

Genome-based taxonomic analysis of the genus Pseudoalteromonas reveals heterotypic synonyms.

The Pseudoalteromonas genus comprises members that have been demonstrated to play significant ecological roles and produce enzymes, natural products, and activities that are beneficial to the environment and economy. A comprehensive evaluation of the genus revealed that the genomes of several Pseudoalteromonas species are highly similar to each other, exceeding species cutoff values. This evaluation involved determining and comparing the average nucleotide identity, in silico DNA-DNA hybridization, average amino acid identity, and the difference in G + C% between Pseudoalteromonas type strains with publicly available genomes. The genome of the Pseudoalteromonas elyakovii type strain was further assessed through additional sequencing and genomic comparisons to historical sequences. These findings suggest that six Pseudoalteromonas species, namely P. mariniglutinosa, P. donghaensis, P. maricaloris, P. elyakovii, P. profundi, and P. issachenkonii, should be reclassified as later heterotypic synonyms of the following validly published species: P. haloplanktis, P. lipolytica, P. flavipulchra, P. distincta, P. gelatinilytica, and P. tetraodonis. Furthermore, two names without valid standing, 'P. telluritireducens' and 'P. spiralis', should be associated with the validly published Pseudoalteromonas species P. agarivorans and P. tetraodonis, respectively.

Marortus luteolus Yu et al. 2019 is a later heterotypic synonym of Zhongshania marina On et al. 2019.

Phylogeny of 16S rRNA gene sequences showed that Marortus luteolus ZX-21T and Zhongshania marina DSW25-10T are closely related, and form a monophyletic clade affiliated with the genus Zhongshania. Whole genome sequence comparisons showed that M. luteolus ZX-21T and Z. marina DSW25-10T shared 78.8 % digital DNA-DNA hybridization, 97.6 % average nucleotide identity and 98.1 % average amino acid identity. These values exceeded the recommended threshold values for species delineation. Thus, based on the principle of priority, we propose the reclassification of Marortus luteolus Yu et al. 2019 as a later heterotypic synonym of Zhongshania marina On et al. 2019.