A polyphasic study was undertaken to clarify the taxonomic position of endospore-forming strains 433-D9, 433-E17 and 121-X1. BOX-PCR-generated fingerprints indicated that they may be members of a single species. 16S rRNA gene sequence similarity demonstrated that a representative of this group, 433-D9, is affiliated closely with Bacillus arvi DSM 16317T (100 %), Bacillus arenosi DSM 16319T (99.8 %) and Bacillus neidei NRRL BD-87T (97.1 %). Sequence similarities revealed Bacillus pycnus NRRL NRS-1691T and several Kurthia species as the next nearest relatives. DNA–DNA hybridization results showed that strain 433-D9 is a member of B. arvi. Detection of l-Lys–d-Asp-based peptidoglycan in strain 433-D9, B. arvi DSM 16317T and B. arenosi DSM 16319T was in agreement with their close relationship, but differentiated these strains from B. neidei NRRL BD-87T and B. pycnus NRRL NRS-1691T, for which l-Lys–d-Glu was reported. A similar quinone system was detected in strains 433-D9, 433-E17, 121-X1, B. arvi DSM 16317T, B. arenosi DSM 16319T and B. neidei NRRL BD-87T. This system, unusual for bacilli, consisted of the major compound menaquinone MK-8 (69–80 %) and moderate amounts of MK-7 (19–30 %). This observation was in contrast to the predominance of MK-7 of the closest relative B. pycnus NRRL NRS-1691T, as also reported for representatives of the closely related non-endospore-forming genus Kurthia. Strains 433-D9, B. arvi DSM 16317T and B. arenosi DSM 16319T exhibited homogeneous and discriminative polar lipid profiles and fatty acid profiles consisting of major acids i-C15 : 0 and ai-C15 : 0 and moderate amounts of i-C17 : 1 ω10c and i-C17 : 1 I/ai-C17 : 1 B that discriminated them from closely related strains such as B. neidei NRRL BD-87T. On the basis of clear-cut discriminative chemotaxonomic markers, we propose strains 433-D9, 433-E17 and 121-X1, B. arvi DSM 16317T, B. arenosi DSM 16319T and B. neidei NRRL BD-87T to be reclassified within a separate genus. For this new taxon, we propose the name Viridibacillus gen. nov., and we propose the reclassification of Bacillus arvi, Bacillus arenosi and Bacillus neidei as Viridibacillus arvi gen. nov., comb. nov. (the type species of Viridibacillus, with the type strain DSM 16317T =LMG 22165T), Viridibacillus arenosi comb. nov. (type strain DSM 16319T =LMG 22166T) and Viridibacillus neidei comb. nov. (type strain NRRL BD-87T =DSM 15031T =JCM 11077T).

[1] Although the low-order present stress field of most continents is fairly well established, information on paleostress fields is generally sparse. Knowledge of paleostresses is crucial for understanding brittle tectonic reactivation through time. The Indian-Australian plate lends itself well to a reconstruction of paleostresses, as it has undergone enormous changes in plate-driving forces through the Tertiary, and there is a rich record of fault reactivation from sedimentary basins. We reconstruct the plate boundary configuration and age-area distribution of ocean crust around Australia through time to obtain estimates for ridge push, slab pull, and collisional forces acting on the Indian-Australian plate since the Eocene. Other model parameters we explore are the effects of the Australian-Antarctic discordance and the mechanical strength of the Australian continental margin. We apply these constraints to model the orientation of the maximum horizontal compressive stress (S Hmax ) regime for the present, early Miocene, and early Eocene using the commercial software ABAQUS 2 along with the optimization software Nimrod/O. We use an elastic two-dimensional plane stress finite element model with a resolution of $0.2°in both longitude and latitude. Realistic elastic parameters representing different rock types and geologic provinces for the Australian continent have been included to model the stress field of a heterogeneous plate. We show that spatially significant rotations of S Hmax directions can be modeled as a consequence of perturbations of S Hmax in areas of juxtaposed rigid and compliant rheologies. The absence of the collisional Papua New Guinea boundary in the Miocene and reduced ridge push force from the south result in stress directions considerably different from the present. Stress directions over the northern Australian continent in the early Miocene in particular show large disparity with present stress directions. Stress orientations for the Australian plate during the early Eocene are controlled predominantly by ridge push forces arising from spreading in the Wharton Basin in the Indian Ocean and vary substantially with stress directions in the early Miocene and the present because of the drastically different plate geometry and boundary configurations. Fault reactivation histories observed on the northwest shelf of Australia and in the Bass Strait region are consistent with modeled changes in stress directions through time.

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