see [@SM]). In contrast, for higher $\text{Pe}$ we find a change in tendency from lanes to bands since $P_y\approx P_x$, showing that the system’s structure is characterized by a coexistence of bands and lanes in this regime. Why lanes appear more frequently than bands at small persistence? When velocity alignment is much faster than rotational diffusion ($\text{g}\gg \text{Pe}$), particles aggregation is controlled by alignment, following the mechanism depicted in Fig. \[aline\] (left). In this high coupling regime, rotational diffusion is largely suppressed ($\tau\gg\tau_K$). Once a particle aligns with the cluster its orientation gets kinetically frozen, due to the separation of time scales between $\tau$ and $\tau_K$. In this regime, a coherently moving cluster grows by the aggregation of particles along their direction of motion, favoring a lane-like structure (see Fig. \[fig:laneband\] and Movie 1 in the Supplementary Information [@SM]).

As $\text{Pe}$ increases, fluctuations are more severe and the orientation of the particles cannot be considered as frozen anymore since the persistence time $\tau$ can be of the order of magnitude of $\tau_K$. Therefore, a reorientation event might make a particle leave the surface of the cluster if its diffusion time is short enough compared to $\tau_K$. In the absence of 