Pseudonocardia wallangbongensis sp. nov., isolated from small mountain (parasitic volcano), with a proposal of Actinospineispora gen. nov. and reclassification of two Pseudonocardia species as later heterotypic synonyms of preexisting species.

Genome analysis of the genus Pseudonocardia was performed based on 92 single-copy core genes of 56 genome sequences including that of an environmental strain, DLS-67T. The genus formed a well-defined monophyletic clade but was further divided into two clusters confirmed by coherent tree topology and amino acid identity values. Most of the species were assigned to the Pseudonocardia I (core cluster), while three species (Pseudonocardia acaciae DSM 45401T, Pseudonocardia eucalypti CM 18303T and Pseudonocardia spinosispora DSM 44797T) were included in the second cluster (Pseudonocardia II). Morphologically, members of these two clusters differed from each other in that species of Pseudonocardia II produced spiny spores, while nearly all species of the core Pseudonocardia produced spores with smooth surfaces. Considering the inter-cluster values (65.1%) of amino acid identity and morphological distinctness, it is proposed that three species of the Pseudonocardia II be transferred to a new genus (Actinospineispora gen. nov.) different from the Pseudonocardia. In addition, based on the values of orthologous average nucleotide identity and digital DNA-DNA hybridization, Pseudonocardia dioxanivorans and Pseudonocardia sichuanensis are described as later heterotypic synonyms of Pseudonocardia benzenivorans and Pseudonocardia kunmingensis, respectively, with Pseudonocardia saturnea NBRC 14499 (=DSM 660=ATCC 15778=IMSNU 20052=NRRL B-16172) as a different strain of Pseudonocardia autotrophica. In addition, based on polyphasic data presented here, an environmental strain is proposed as a new species of the genus Pseudonocardia, for which the name Pseudonocardia wallangbongensis sp. nov. is proposed, with the type strain DLS-67T (=KCTC 19563T=DSM 45253T).