sp. nov., isolated from Darangshi Oreum (a volcanic cone), and the reclassification of Lu . 2003 as a later heterotypic synonym of (Shinobu 1962) Preobrazhenskaya . 1975 (Approved Lists 1980).

Two mycelium-forming actinobacterial strains, designated as DLS-47 and DLS-62, were isolated from volcanic ash collected from the surface of a rock on the peak of Darangshi Oreum (a volcanic cone) in Jeju, Republic of Korea, and their taxonomic positions were investigated by a polyphasic approach. Both of the isolates showed growth at 20-42 °C, pH 6.0-9.0 and 0-1% (w/v) NaCl. Furthermore, DLS-47 was found to grow at 45 °C, while strain DLS-62 grew at pH 10.0 and 3% (w/v) NaCl. The 16S rRNA gene-based phylogeny showed that both of the isolates belonged to the genus ; strain DLS-47 was most closely related to DSM 45346 (100% sequence identity), while strain DLS-62 formed a tight cluster with DSM 45347 (99.5% sequence similarity). Morphological and chemotaxonomic characteristics supported the affiliation of the two isolates to the genus . Phylogenomic analysis based on 92 core gene sequences showed that both of the isolates were most closely related to DSM 45346. Strain DLS-47 shared 100% of orthologous average nucleotide identity and digital DNA-DNA hybridization values with DSM 45346, while strain DLS-62 showed orthologous average nucleotide identity ≤89.8% and digital DNA-DNA hybridization values ≤39.4% with strain DLS-47 and members of the genus . The results of phenotypic assays and comparison of overall genomic relatedness indices support the conclusion that strain DLS-47 (= KACC 23347=DSM 116423) is a strain of , while strain DLS-62 (= KACC 23345 = DSM 116424) represents a new species of the genus , for which the name sp. nov. is proposed. Also, Lu 2003 is reclassified as a later heterotypic synonym of (Shinobu 1962) Preobrazhenskaya . 1975 (Approved Lists 1980) based on analysis of overall genomic relatedness indices and phenotypic similarity.