Complex sentence: Researchers are particularly interested in the "G. cruciata" plant as the "P. rebeli" and "G. cruciata" are both endangered, and lepidopterists feel that conserving the "P. rebeli" requires focusing conservation efforts on "G. cruciata" as well.
Split into simpler sentences: Researchers are particularly interested in the "G. cruciata" plant because both the "P. rebeli" and "G. cruciata" are endangered. As a result, lepidopterists believe that conserving the "P. rebeli" requires focusing conservation efforts on preserving "G. cruciata" as well.