Complex sentence: The adult is a medium-sized damselfly (wingspan 45mm, length 40mm), dusky-grey on dorsal surfaces graduating to light bluish-green on the sides and beneath.
Split into simpler sentences: The adult is a medium-sized damselfly about 40 millimeters long with a wingspan around 45 millimeters. It is dusky-grey on dorsal surfaces graduating to light bluish-green on the sides and beneath.