- Volume 70, Issue 6, 2020

The strain DMKU-XD44, representing an anamorphic novel yeast species, was isolated from soil collected in a peat swamp forest (PSF) area in Rayong Botanical Garden in eastern Thailand. On the basis of sequence analysis of the D1/D2 region of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) region, Teunia cuniculi CBS 10309T was the most closely related species. The novel species differed from the T. cuniculi type by 2.5 % (14 nucleotide substitutions) in the D1/D2 region of the LSU rRNA gene and by 8.0 % (40 nucleotide substitutions) in the ITS region. The results of a phylogenetic analysis, based on the combined sequences of the ITS region and the D1/D2 region, indicated that DMKU-XD44 represents a member of the Teunia clade in the Cryptococcaceae (Tremellales, Tremellomycetes, Agaricomycotina and Basidiomycota) and is phylogenetically distinct from other species of the genus Teunia in the clade. Therefore, DMKU-XD44 represents a novel species of the genus Teunia. The name Teunia siamensis f.a., sp. nov. is proposed. The holotype is DMKU-XD44, while the MycoBank number is MB 832816.

Twenty-one psychrophilic yeast isolates related to the Camptobasidiaceae family in the Microbotryomycetes class were obtained from ice collected from cold environments worldwide. A new psychrophilic species from the recently described genus Cryolevonia, Cryolevania giraudoae is proposed to accommodate 18 isolates from Patagonia (Argentina) and Antarctica (holotype CRUB 2086T). In addition, a new psychrophilic species in the genus Camptobasidium is described as Camptobasidium gelus sp. nov. (holotype CBS 8941T), based on three isolates from glacial ice in the Russel glacier (Greenland ice sheet) and Antarctica. The strict psychrophilic profile is the salient feature of both novel species.

Phylogenetic analysis based on 16S rRNA gene sequences of the genus Streptomyces showed the presence of six distinguishable clusters, with 100 % sequence similarity values among strains in each cluster; thus they shared almost the same evolutionary distance. This result corroborated well with the outcome of core gene (orthologous gene clusters) based genome phylogeny analysis of 190 genomes including the Streptomyces species in those six clusters. These preeminent results led to an investigation of genome-based indices such as digital DNA–DNA hybridization (dDDH), average nucleotide identity (ANI) and average amino acid identity (AAI) for the strains in those six clusters. Certain strains recorded genomic indices well above the threshold values (70 %, 95–96 % and >95 % for dDDH, ANI and AAI, respectively) determined for species affiliation, suggesting only one type strain belongs to described species and the other(s) may need to be reduced in taxa to a later heterotypic synonym. To conclude, the results of comprehensive analyses based on phylogenetic and genomic indices suggest that the following six reclassifications are proposed: Streptomyces flavovariabilis as a later heterotypic synonym of Streptomyces variegatus ; Streptomyces griseofuscus as a later heterotypic synonym of Streptomyces murinus ; Streptomyces kasugaensis as a later heterotypic synonym of Streptomyces celluloflavus ; Streptomyces luridiscabiei as a later heterotypic synonym of Streptomyces fulvissimus ; Streptomyces pharetrae as a later heterotypic synonym of Streptomyces glaucescens ; and Streptomyces stelliscabiei as a later heterotypic synonym of Streptomyces bottropensis .

According to Rule 37a of the International Code of Nomenclature of Prokaryotes, the name of a taxon must be changed if the nomenclatural type of the taxon is excluded. Recently, in a transfer of actinobacterial species, three species – Friedmanniella endophytica Tuo et al. 2016, Lysinimicrobium sediminis Hamada et al. 2017 and Lechevalieria rhizosphaerae Zhao et al. 2017 – were not transferred with their type species. Therefore, to resolve these nomenclatural issues, Microlunatus kandeliicorticis nom. nov., Demequina sediminis comb. nov. and Lentzea rhizosphaerae comb. nov. are proposed, respectively.

The genus Rhodopseudomonas , containing purple nonsulfur photosynthetic Proteobacteria, has a number of strains that belong to different species, although many of them are collectively called Rhodopseudomonas palustris . The type species R. palustris and closely related species are the focus of this paper. The comparison of available genome sequences indicate that the following Rhodopseudomonas species are well recognized: R. palustris (strains ATH 2.1.6T=DSM 123T=NBRC 100419T and BisB5), Rhodopseudomonas rutila (strains R1T, DSM 126, CGA009, ATH 2.1.37, Eli 1980, ATCC 17001 and TIE1), Rhodopseudomonas pentothenatexigens JA575T and Rhodopseudomonas faecalis JCM 11668T. Other strains for which genome sequences are available are distinct from these four species. Evidence is presented that R. palustris strain ATH 2.1.6T–KCM as obtained directly from the van Niel collection by one of us (T.E.M.) is identical to the DSMZ deposit DSM 123T of ATH 2.1.6T, but not to the deposit at ATCC 17001. The amino acid sequences of the cytochromes C2 and C556 from R. palustris strain ATH 2.1.6T–KCM are in complete agreement with the translated genome sequences of R. palustris DSM 123T. In addition, the 16S rRNA gene sequence of R. palustris NBRC 100419T completely matches that of strain DSM 123T. In conclusion, the type strain of R. palustris ATH 2.1.6T is correctly represented by DSM 123T and NBRC 100419T. However, the deposit at ATCC 17001 has properties that do not conform with properties of authentic R. palustris , but rather indicate that this is a strain of R. rutila . The previously suggested assignment of the type strain of R. palustris DSM 123T to the new species R. pseudopalustris was incorrect because strain DSM 123T is the authentic type strain of R. palustris .