  Microtearing modes are an important drive of turbulent heat transport in
present-day fusion plasmas. We investigate their linear stability under
very-low collisionality regimes, expected for the next generations of devices,
using gyrokinetic and drift-kinetic approaches. At odds with current opinion,
we show that collisionless microtearing instabilities may occur in certain
experimental conditions, particularly relevant for such devices as reversed
field pinches and spherical tokamaks.
