look for common entries in two data frames

df1:
 state group species
1 CA 2 cat, dog, chicken, mouse
2 CA 1 cat
3 NV 1 dog, chicken
4 NV 2 chicken
5 WA 1 chicken, rat, mouse, lion
6 WA 2 dog, cat
7 WA 3 dog, chicken
8 WA 4 cat, chicken

df2:
 state special_species
1 CA cat
2 CA chicken
3 CA mouse
4 WA cat
5 WA chicken
6 NV dog

I'm interested in determining which of the special_species from df2 are present in df1. I'd like a new dataframe that has the state, group, and the special_species.

Anticipated output:

state group special_species
CA 2 cat, chicken, mouse
CA 1 cat
NV 1 dog
NV 2 NA
WA 1 chicken
WA 2 cat
WA 3 chicken
WA 4 cat, chicken