Reclassification of Streptosporangium soli Yin et al. 2025 as Dolomitihabitans soli gen. nov., comb. nov.

Streptosporangium is the second largest genus within the family Streptosporangiaceae, comprising 34 species with validly published names. One of the most recently described members of the genus is Streptosporangium soli, assigned on the basis of chemotaxonomic and morphological features and a limited phylogenetic analysis. Here, we reinvestigate the taxonomic assignment of S. soli KLBMP 9127T using a polyphasic approach. We show that despite possessing chemotaxonomic and morphological features characteristic of the genus Streptosporangium, S. soli does not cluster with other members of the genus Streptosporangium in a 16S rRNA gene-based phylogeny of the entire family Streptosporangiaceae nor within a whole-genome-based phylogenomic tree. S. soli can be distinguished from its closest relatives within the phylogenomic tree using spore morphology and chemotaxonomic markers. Overall genome relatedness indices further suggest that S. soli represents a novel lineage within the family Streptosporangiaceae, sharing less than 71% average amino acid identity with the type strain of the type species of every genus with a validly published name within the family. Accordingly, we propose reassigning S. soli as the type species of a novel genus within the family Streptosporangiaceae, Dolomitihabitans soli gen. nov., comb. nov. We also revisit the 1987 proposal made by Kudo and Seino for Streptosporangium indianense to be reclassified as a member of the genus Streptomyces. On the basis of a wealth of morphological, chemotaxonomic and phylogenetic data, we show that S. indianense is not a member of the genus Streptosporangium, or even the family Streptosporangiaceae. Rather, S. indianense is most closely associated with the genus Streptomyces, family Streptomycetaceae.