taxi-, tax-, taxo-, taxio-, -taxia, -taxis, -taxy, tact-, -tactic, -tactical, -tactics

(Greek: arrangement, order, put in order, orientation; the movements or directed responses of motile organisms to stimuli, as indicated by the combining roots)

Animal taxonomy.
zygotaxis (s) (noun), zygotaxes (pl)
The mutual attraction between male and female gametes: The shared affinity betwixt or between two suspensors which is instantly responsible for sexual union or conjugation.