Complex sentence: In 1939 Hermann O. Sleumer described many additional Malesian species especially in New Guinea, in 1955 he published a revision of the genus, and in 1956 his treatment of the genus in "Flora Malesiana" was published.
Split into simpler sentences: In 1939 Hermann O. Sleumer described many additional Malesian species especially in New Guinea. In 1956 his treatment of the genus in "Flora Malesiana" was published.