  We study the valence band structure of ReSe$_{2}$ crystals with varying
thickness down to a single layer using nanoscale angle-resolved photoemission
spectroscopy and density functional theory. The width of the top valence band
in the direction perpendicular to the rhenium chains decreases with decreasing
number of layers, from 280 meV for the bulk to 61 meV for monolayer. This
demonstrates increase of in-plane anisotropy induced by changes in the
interlayer coupling and suggests progressively more one-dimensional character
of electronic states in few-layer rhenium dichalcogenides.
