Geodermatophilaceae (order Geodermatophilales, class Actinobacteria) form a comparatively isolated family within the phylum Actinobacteria and harbor many strains adapted to extreme ecological niches and tolerant against reactive oxygen species. Clarifying the evolutionary history of Geodermatophilaceae was so far mainly hampered by the insufficient resolution of the main phylogenetic marker in use, the 16S rRNA gene. In conjunction with the taxonomic characterisation of a motile and aerobic strain, designated YIM M13156T and phylogenetically located within the family, we here carried out a phylogenetic analysis of the genome sequences now available for the type strains of Geodermatophilaceae and re-analyzed the previously assembled phenotypic data. The results indicated that the largest genus, Geodermatophilus, is not monophyletic, hence the arrangement of the genera of Geodermatophilaceae must be reconsidered. Taxonomic markers such as polar lipids and fatty-acids profile, cellular features and temperature ranges are indeed heterogeneous within Geodermatophilus. In contrast to previous studies, we also address which of these features can be interpreted as apomorphies of which taxon, according to the principles of phylogenetic systematics. We thus propose a novel genus, Klenkia, with the type species Klenkia marina sp. nov. and harboring four species formerly assigned to Geodermatophilus, G. brasiliensis, G. soli, G. taihuensis, and G. terrae. Emended descriptions of all species of Geodermatophilaceae are provided for which type-strain genome sequences are publicly available. Our study again demonstrates that the principles of phylogenetic systematics can and should guide the interpretation of both genomic and phenotypic data.

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Modestobacter italicus sp. nov., isolated from Carrara marble quarry 1 and emended descriptions of the genus Modestobacter and the species 2 Modestobacter marinus, Modestobacter multiseptatus, Modestobacter 3 roseus and Modestobacter versicolor 4 5 Phone: +44 (0) 191 208 4943 22 23 24 Running title: Modestobacter italicus, sp. nov. and emended descriptions. 25 26 The journal's contents category (New taxa-Actinobacteria) 27 The GenBank/EMBL/DDBJ whole-genome sequence accession number of strain BC 501 T =DSM 28 44449 T =CECT 9708 T is FO203431. The GenBank/EMBL/DDBJ 16S rRNA gene sequence 29 accession number is MK020151. 30 31 32 33 A Gram reaction-positive, aerobic bacterial strain showing coccoid cells and designated as BC 34 501 T was isolated from a black patina of Carrara marble block surface in the Gioia quarry in 35 Tuscany, Italy. A polyphasic study was carried out to clarify the taxonomic status of strain BC 36 501 T within the evolutionary radiation of the genus Modestobacter. Phenotypic and genotypic 37 characteristics as well as phylogenetic distinctiveness confirmed that it represents a novel species 38 in the genus Modestobacter, for which the name Modestobacter italicus sp. nov. is proposed. The 39 type strain is BC 501 T (= DSM 44449 T = CECT 9708 T ). Emended descriptions of the genus 40 Modestobacter and the species Modestobacter marinus, Modestobacter multiseptatus, 41 Modestobacter roseus and Modestobacter versicolor are also proposed. 42 43 Keywords: Geodermatophilaceae, digital DDH, phenotyping, oxidative stress 44 45 The genus Modestobacter [1], of the family Geodermatophilaceae [2], encompasses seven validly 46 named species: Modestobacter multiseptatus [1], as the type species, Modestobacter caceresii [3], 47 Modestobacter lapidis [4], Modestobacter marinus [5], Modestobacter muralis [4], Modestobacter 48 roseus [6], and Modestobacter versicolor [7] and an effectively published species 'Modestobacter 49 lacusdianchii' [8]. Representatives of the genus are recognised by a combination of chemotaxonomic, 50 morphological and physiological properties [3] and can be distinguished from other genera in 51 Geodermatophilaceae by 16S rRNA phylogenetic inference [8] and their polar lipids profiles [9]. 52 Representatives of Geodermatophilaceae are well known for their tolerance to oxidative stress and 53 hence well adapted to harsh environmental conditions [3, 10, 11, 12, 13]. Species in Modestobacter 54 were mainly isolated from oligotrophic ecosystems such as Antarctica [1], desert soils [3], deep sea 55 sediments [5] or deteriorated sandstones [4], although some were also recovered from others 56 environments such as biocrusts [7], plants roots [6] and algae mats [8]. 57 Monuments and rocks surfaces exposed both indoor and outdoor are peculiar and poorly studied 58 habitats inhabited by a wide range of Gram-positive strains belonging to the class Actinobacteria [14] 59 frequently classified as representing novel taxa [15, 16, 17, 18]. Strain BC 501 T was isolated from a 60 Carrara marble block at ...

Three presumptive Modestobacter strains isolated from a high altitude Atacama Desert soil were the subject of a polyphasic study. The isolates, strains 1G4T, 1G51 and 1G52, were found to have chemotaxonomic and morphological properties that were consistent with their assignment to the genus Modestobacter . They formed a well supported clade in Modestobacter 16S rRNA gene trees and were most closely related to the type strain of ‘Modestobacter excelsi’ (99.8–99.9% similarity). They were also closely related to the type strains of Modestobacter caceresii (99.6 % similarity), Modestobacter italicus (99.7–99.9% similarity), Modestobacter lacusdianchii (98.4–99.2% similarity), Modestobacter marinus (99.4–99.5% similarity) and Modestobacter roseus (99.3–99.5% similarity), but were distinguished from their closest relatives by a combination of phenotypic features. Average nucleotide identity and digital DNA:DNA hybridization similarities drawn from comparisons of draft genome sequences of isolate 1G4T and its closest phylogenetic neighbours mentioned above, were well below the threshold used to assign closely related strains to the same species. The close relationship between isolate 1G4T and the type strain of M. excelsi was showed in a phylogenomic tree containing representative strains of family Geodermatophilaceae . The draft genome sequence of isolate 1G4T (size 5.18 Kb) was shown to be rich in stress related genes providing further evidence that the abundance of Modestobacter propagules in Atacama Desert habitats reflects their adaptation to the harsh environmental conditions prevalent in this biome. In light of all of these data it is proposed that the isolates be assigned to a novel species in the genus Modestobacter . The name proposed for this taxon is Modestobacter altitudinis sp. nov., with isolate 1G4T (=DSM 107534T=PCM 3003T) as the type strain.