 Lenk et al . ( 1999 ) discovered considerable differences between the two conventionally recognized subspecies of B. gabonica described above . According to their research , these two subspecies are as different from each other as they are from B. nasicornis . Consequently , Lenk et al . ( 1999 ) regard the western form as a separate species , B. rhinoceros . 
 Lenk et al . ( 1999 ) discovered considerable differences between the two conventionally recognized subspecies of B. gabonica described above . According to their research , these two subspecies <a href='drop_aux' title='1'><mark>are</mark></a>as different from each other as they are from B. nasicornis . Consequently , Lenk et al . ( 1999 ) regard the western form as a separate species , B. rhinoceros . 
Lenk et al . ( 1999 ) discovered considerable differences between the two conventionally recognized subspecies of B. gabonica described above . According to their research , dem 2 subspecies as different from each other as they are from B. nasicornis . Consequently , Lenk et al . ( 1999 ) regard the western form as a separate species , B. rhinoceros .