  The problem of the linear microtearing mode in a slab magnetised plasma, and
its connection to kinetic reconnecting modes, is addressed. Electrons are
described using a novel hybrid fluid-kinetic model that captures electron
heating, ions are gyrokinetic. Magnetic reconnection can occur as a result of
either electron conductivity and inertia, depending on which one predominates.
We eschew the use of an energy dependent collision frequency in the collisional
operator model, unlike previous works. A model of the electron conductivity
that matches the weakly collisional regime to the exact Landau result at zero
collisionality and gives the correct electron isothermal response far from the
reconnection region is presented. We identify in the breaking of the
constant-$A_{\parallel}$ approximation the necessary condition for microtearing
instability in the collisional regime. Connections with the theory of
collisional non-isothermal (or semicollisional) and collisionless
tearing-parity electron temperature gradient driven (ETG) modes are elucidated.
