Osat_a    Osat_a # just one cluster member
Atha_b    Atha_b # >1 cluster member, this & next line = 2 members
Fves_d    Fves_d # this & next 2 lines = 3 cluster members
Osat_h    Osat_h
Atha_b    Mtru_c 
Fves_d    Osat_e
Atha_g    Atha_g # just 1 cluster member
Fves_d    Atha_f
Osat_h    Atha_i
...       ...