  Fermionic dark matter interacting with the Standard Model sector through a
pseudoscalar portal could evade the direct detection constraints while
preserving a WIMP miracle. We study the LHC constraints on the pseudoscalar
production in simplified models with the pseudoscalar either dominantly coupled
to b quarks or tau leptons and explore their implications for the GeV excesses
in gamma ray observations. We also investigate models with new vector-like
fermions that could realize the simplified models of pseudoscalar portal dark
matter. These models yield new decay channels and signatures of vector-like
fermions, for instance, bbb, btautau, and tautautau resonances. Some of the
signatures have already been strongly constrained by the existing LHC searches
and the parameter space fitting the gamma ray excess is further restricted. On
the other hand, the pure tau-rich final state is only weakly constrained so far
due to the small electroweak production rate.
