Surniculus is a small genus of birds in the cuckoo family whose four members are found in tropical Asia and the Philippines. 

1/ Square-tailed drongo-cuckoo (Cu cu đen, Surniculus lugubris) 
2/ Fork-tailed drongo-cuckoo (Surniculus dicruroides)

Surniculus: possibly from French Surnicou: sournois deceitful; Coucou cuckoo. It is also likely a portmanteau of the genus name Surnia (owl) and Cuculus (cuckoo). It can also be interpreted from Latin as a combination of surnos (or sournos) for "deceitful" and cuculus for "cuckoo," referencing the bird's deceptive nature. 
culus: In Latin, "culus" is a vulgar word meaning "buttocks," "posterior," or "anus". The Latin suffix -culus is a diminutive suffix used to mean "little" or "small," similar to the function of suffixes in both Latin and English.