Here are some of my guesses:
handsy humanoid | atmospheric ambience
primate / climate
headdress holiday | chromosomal cross-up
carnival / carcinogenic
lacking logic | evoking enthusiasm
irrational / veneration
multi-tasking mycota | mammals' mark (not sure about the "multitasking" part...)
portabella / bellybutton
celestial species | bachelor brotherhood
extraterrestial / fraternity
wowing wizardry | hearty herb
brandish / horseradish
gun; gum | worthless whistle
trident / deride (probably wrong but oh well)
supervised span | pulsate periodically
hospitalization / palpitate
replicate ravenously | water ward
proliferate / lifesaver
palpable proximity | person picked
imminent / nominee