  Momentum-indirect excitons composed of electrons and holes in different
valleys define optoelectronic properties of many semiconductors, but are
challenging to detect due to their weak coupling to light. The identification
of an excitons' valley character is further limited by complexities associated
with momentum-selective probes. Here, we study the photoluminescence of
indirect excitons in controllably strained prototypical 2D semiconductors
(WSe$_2$, WS$_2$) at cryogenic temperatures. We find that these excitons i)
exhibit valley-specific energy shifts, enabling their valley fingerprinting,
and ii) hybridize with bright excitons, becoming directly accessible to optical
spectroscopy methods. This approach allows us to identify multiple previously
inaccessible excitons with wavefunctions residing in K, $\Gamma$, or Q valleys
in the momentum space as well as various types of defect-related excitons.
Overall, our approach is well-suited to unravel and tune intervalley excitons
in various semiconductors.

Mesoscale and Nanoscale Physics;Other Condensed Matter